The AVR Microcontroller and embedded Systems: Using assembly and C

Online Instructor’s Manual
to accompany
The AVR Microcontroller and
Embedded Systems: Using Assembly
and C
1st Edition
Muhammad Ali Mazidi
DeVry University
Sarmad Naimi
Sepehr Naimi
Prentice Hall
Boston Columbus Indianapolis New York San Francisco Upper Saddle River
Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montreal Toronto
Delhi Mexico City Sao Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo
___________________________________________________________________________________________
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have been printed in initial caps or all caps.
10 9 8 7 6 5 4 3 2 1
ISBN-13: 978-0-13-512363-8
ISBN-10:
0-13-512363-1
Contents
CHAPTER 0: INTRODUCTION TO COMPUTING..................................................................... 5
SECTION 0.1: NUMBERING AND CODING SYSTEMS................................................... 5
SECTION 0.2: DIGITAL PRIMER ........................................................................................ 6
SECTION 0.3: SEMICONDUCTOR MEMORY .................................................................. 8
SECTION 0.4: CPU AND HARVARD ARCHITECTURE ................................................ 10
CHAPTER 1: THE AVR MICROCONTROLLERS: HISTORY AND FEATURES.................. 11
SECTION 1.1: MICROCONTROLLERS AND EMBEDDED PROCESSORS............... 11
SECTION 1.2: OVERVIEW OF THE AVR FAMILY ....................................................... 11
CHAPTER 2: AVR ARCHITECTURE & ASSEMBLY LANGUAGE PROGRAMMING ....... 13
SECTION 2.1: THE GENERAL PURPOSE REGISTERS IN THE AVR........................ 13
SECTION 2.2: THE AVR DATA MEMORY ...................................................................... 13
SECTION 2.3: USING INSTRUCTIONS WITH THE DATA MEMORY....................... 14
SECTION 2.4: AVR STATUS REGISTER .......................................................................... 15
SECTION 2.5: AVR DATA FORMAT AND DIRECTIVES.............................................. 16
SECTION 2.6: INSTRUCTION TO AVR ASSEMBLY PROGRAMMING AND .......... 17
SECTION 2.7: ASSEMBLING AN AVR PROGRAM........................................................ 17
SECTION 2.8: THE PROGRAM AND PROGRAM ROM SPACE IN THE AVR ......... 18
SECTION 2.9: RISC ARCHITECTURE IN THE AVR ..................................................... 20
CHAPTER 3: BRANCH, CALL AND TIME DELAY LOOP .................................................... 21
SECTION 3.1: BRANCH INSTRUCTIONS AND LOOPING........................................... 21
SECTION 3.2: CALL INSTRUCTIONS AND STACK ...................................................... 21
SECTION 3.3: AVR TIME DELAY AND INSTRUCTION PIPELINE ........................... 22
CHAPTER 4: AVR I/O PORT PROGRAMMING ...................................................................... 24
SECTION 4.1: I/O PORT PROGRAMMING IN AVR ...................................................... 24
SECTION 4.2: I/O BIT MANIPULATION PROGRAMMING......................................... 25
CHAPTER 5: ARITHMETIC, LOGIC INSTRUCTIONS, AND PROGRAMS.......................... 29
SECTION 5.1: ARITHMETIC INSTRUCTIONS............................................................... 29
SECTION 5.2: SIGNED NUMBER CONCEPTS AND ARITHMETIC OPERATIONS 31
SECTION 5.3: LOGIC AND COMPARE INSTRUCTIONS............................................. 31
SECTION 5.4: ROTATE AND SHIFT INSTRUCTIONS AND DATA SERIALIZATION
................................................................................................................................................... 32
SECTION 5.5: BCD AND ASCII CONVERSION............................................................... 33
CHAPTER 6: AVR ADVANCED ASSEMBLY LANGUAGE PROGRAMMING ................... 35
SECTION 6.1: INTRODUCING SOME MORE ASSEMBLER DIRECTIVES .............. 35
SECTION 6.2: REGISTER AND DIRECT ADDRESSING MODES ............................... 35
SECTION 6.3: REGISTER INDIRECT ADDRESSING MODE....................................... 36
SECTION 6.4: LOOK-UP TABLE AND TABLE PROCESSING..................................... 37
SECTION 6.5: BIT-ADDRESSABILITY ............................................................................. 40
SECTION 6.6: ACCESSING EEPROM IN AVR................................................................ 42
SECTION 6.7: CKECKSUM AND ASCII SUBROUTINES .............................................. 45
SECTION 6.8: MACROS ....................................................................................................... 48
CHAPTER 7: AVR PROGRAMMING IN C ............................................................................... 49
SECTION 7.1: DATA TYPES AND TIME DELAYS IN C................................................ 49
SECTION 7.2: I/O PROGRAMMING IN C ........................................................................ 49
SECTION 7.3: LOGIC OPERATIONS IN C....................................................................... 51
SECTION 7.4: DATA CONVERSION PROGRAMS IN C................................................ 52
SECTION 7.6: MEMORY ALLOCATION IN C ................................................................ 53
CHAPTER 8: AVR HARDWARE CONNECTION .................................................................... 55
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
3
SECTION 8.1: ATMEGA32 PIN CONNECTION .............................................................. 55
SECTION 8.2: AVR FUSE BITS........................................................................................... 55
SECTION 8.3: EXPLAINING THE INTEL HEX FILE FOR AVR ................................. 55
SECTION 8.4: AVR PROGRAMMIN AND TRAINER BOARD ..................................... 56
CHAPTER 9: AVR TIMER PROGRAMMING IN ASSEMBLY AND C.................................. 57
SECTION 9.1: PROGRAMMING TIMERS 0, 1, AND 2 ................................................... 57
SECTION 9.2: COUNTER PROGRAMMING ................................................................... 59
SECTION 9.3: PROGRAMMING TIMERS IN C .............................................................. 60
Chapter 10: INTERRUPT PROGRAMMING IN ASSEMBLY AND C ..................................... 65
SECTION 10.1: AVR INTERRUPTS ................................................................................... 65
SECTION 10.2: PROGRAMMING TIMER INTERRUPTS ............................................. 65
SECTION 10.3: PROGRAMMING EXTERNAL HARDWARE INTERRUPTS ........... 68
SECTION 10.4: INTERRUPT PRIORITY IN THE AVR.................................................. 70
CHAPTER 11: AVR SERIAL PORT PROGRAMMING IN ASSEMBLY AND C ................... 71
SECTION 11.1: BASICS OF SERIAL COMMUNICATION ............................................ 71
SECTION 11.2: ATMEGA32 CONNECTION TO RS232 ................................................. 71
SECTION 11.3: AVR SERIAL PORT PROGRAMMING IN ASSEMBLY..................... 72
SECTION 11.4: AVR SERIAL PORT PROGRAMMING IN C........................................ 74
CHAPTER 12: LCD AND KEYBOARD INTERFACING ......................................................... 76
SECTION 12.1: LCD INTERFACING ................................................................................. 76
SECTION 12.2: KEYBOARD INTERFACING .................................................................. 76
CHAPTER 13: ADC, DAC, AND SENSOR INTERFACING .................................................... 77
SECTION 13.1: ADC CHARACTERISTICS ...................................................................... 77
SECTION 13.2: ADC PROGRAMMING IN THE ATMEGA32 ....................................... 77
SECTION 13.3: SENSOR INTERFACING AND SIGNAL CONDITIONING ............... 78
SECTION 13.4: DAC INTERFACING................................................................................. 78
Chapter 14: RELAY, OPTOISOLATOR, AND STEPPER MOTOR INTERFACING WITH
AVR .............................................................................................................................................. 80
SECTION 14.1: RELAYS AND OPTOISOLATORS ......................................................... 80
SECTION 14.2: STEPPER MOTOR INTERFACING ....................................................... 80
Chapter 15: INPUT CAPTURE AND WAVE GENERATION IN AVR .................................... 81
SECTION 15.1: WAVE GENERATION USING 8-BIT TIMERS..................................... 81
SECTION 15.2: WAVE GENERATION USING TIMER1 ................................................ 82
SECTION 15.3: INPUT CAPTURE PROGRAMMING..................................................... 84
SECTION 15.4: C PROGRAMMING .................................................................................. 84
Chapter 16: PWM AND DC MOTOR CONTROL ...................................................................... 87
SECTION 16.1: DC MOTOR INTERFACING AND PWM .............................................. 87
SECTION 16.2: PWM MODES IN 8-BIT TIMERS............................................................ 87
SECTION 16.3: PWM MODES IN TIMER1 ....................................................................... 89
Chapter 17: SPI PROTOCOL AND MAX7221 DESPLAY INTERFACING ............................. 92
SECTION 17.1: SPI BUS PROTOCOL ................................................................................ 92
SECTION 17.2: SPI PROGRAMMING IN AVR ................................................................ 92
SECTION 17.3: MAX7221 INTERFACING AND PROGRAMMING ............................. 92
Chapter 18: I2C PROTOCOL AND DS1307 RTC INTERFACING ........................................... 93
SECTION 18.1: I2C BUS PROTOCOL................................................................................ 93
SECTION 18.2: TWI PROGRAMMING IN AVR .............................................................. 93
SECTION 18.3: AVR TWI PROGRAMMING IN ASSEMBLY AN C............................. 93
SECTION 18.4: DS1307 RTC INTERFACING AND PROGRAMMING ........................ 95
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
4
CHAPTER 0: INTRODUCTION TO COMPUTING
SECTION 0.1: NUMBERING AND CODING SYSTEMS
1.
2.
3.
4.
5.
6.
(a) 1210 = 11002
(b) 12310 = 0111 10112
(c) 6310 = 0011 11112
(d) 12810 = 1000 00002
(e) 100010 = 0011 1110 10002
(a) 1001002 = 3610
(b) 10000012 = 6510
(c) 111012 = 2910
(d) 10102 = 1010
(e) 001000102 = 3410
(a) 1001002 = 2416
(b) 10000012 = 4116
(c) 111012 = 1D16
(d) 10102 = 0A16
(e) 001000102 = 2216
(a) 2B916 = 0010 1011 10012, 69710
(b) F4416 = 1111 0100 01002, 390810
(c) 91216 = 1001 0001 00102, 232210
(d) 2B16 = 0010 10112, 4310
(e) FFFF16 = 1111 1111 1111 11112, 6553510
(a) 1210 = 0C16
(b) 12310 = 7B16
(c) 6310 = 3F16
(d) 12810 = 8016
(e) 100010 = 3E816
(a) 1001010 Î 0011 0110
(b) 111001 Î 0000 0111
(c) 10000010 Î 0111 1110
(d) 111110001 Î 0000 1111
7.
(a) 2C+3F = 6B
(b) F34+5D6 = 150A
(c) 20000+12FF = 212FF
(d) FFFF+2222 = 12221
8.
(a) 24F-129 = 12616
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
5
9.
(b) FE9-5CC = A1D16
(c) 2FFFF-FFFFF = 3000016
(d) 9FF25-4DD99 = 5218C16
(a) Hex: 30, 31, 32, 33, 34, 35, 36, 37, 38, 39
(b) Binary: 11 0000, 11 0001, 11 0010, 11 0011, 11 0100, 11 0101, 11 0110, 11
0111, 11 1000, 11 1001.
ASCII (hex) Binary
30
011
0000
31
011
0001
32
011
0010
33
011
0011
34
011
0100
35
011
0101
36
011
0110
37
011
0111
38
011
1000
39
011
1001
0
1
2
3
4
5
6
7
8
9
10.
000000 22 55 2E 53 2E 41 2E 20 69 73 20 61 20 63 6F 75
000010 6E 74 72 79 22 0D 0A 22 69 6E 20 4E 6F 72 74 68
000020 20 41 6D 65 72 69 63 61 22 0D 0A
"U.S.A. is a cou
ntry".."in North
America"..
SECTION 0.2: DIGITAL PRIMER
11.
A
1
B
2
3
4
6
C
12.
A
0
0
0
0
1
1
1
1
B
0
0
1
1
0
0
1
1
C
0
1
0
1
0
1
0
1
5
Y
0
1
1
1
1
1
1
1
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
6
13.
.
A
1
B
2
3
4
6
C
14.
A
0
0
0
0
1
1
1
1
5
B
0
0
1
1
0
0
1
1
C
0
1
0
1
0
1
0
1
Y
0
0
0
0
0
0
0
1
15.
A
1
B
2
3
4
6
C
16.
A
0
0
0
0
1
1
1
1
B
0
0
1
1
0
0
1
1
C
0
1
0
1
0
1
0
1
5
A
0
0
0
0
1
1
1
1
B
0
0
1
1
0
0
1
1
C
0
1
0
1
0
1
0
1
Y
0
1
1
0
1
0
0
1
Y
1
1
1
1
1
1
1
0
17.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
7
A
0
0
0
0
1
1
1
1
B
0
0
1
1
0
0
1
1
C
0
1
0
1
0
1
0
1
Y
1
0
0
0
0
0
0
0
D
X
0
1
Q
NC
0
1
18.
LSB
19.
LSB
20.
CLK
No
Yes
Yes
SECTION 0.3: SEMICONDUCTOR MEMORY
21.
(a) 4
(b) 4
(c) 4
(d) 1 048 576, 220
(e) 1024K
(f) 1 073 741 824, 230
(g) 1 048 576 K
(h) 1024M
(i) 8388608, 8192K
22. Disk storage capacity / size of a page = (2*230) / (25*80) = 1 million pages
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
8
23. (a) 9FFFFh – 10000h = 8FFFFh = 589 824 bytes
(b) 576 kbytes
24. 232 – 1 = 4 294 967 295
25. (a) FFh, 255
(b) FFFFh, 65535
(c) FFFF FFFFh, 4 294 967 295
(d) FFFF FFFF FFFF FFFFh, 18 446 744 073 709 551 615
26. (a) 216 = 64K
(b) 224 = 16M
(c) 232 = 4096 Mega, 4G
(d) 248 = 256 Tera, 262144 Giga, 268435456 Mega
27. Data bus is bidirectional, address bus is unidirectional (exit CPU).
28. The storage of the chip is measured in Megabits while the Computer memory is
measured in Megabytes.
29. True, the more address lines the more memory locations.
30. True, the memory location size is fixed.
31. True, the more data lines the more memory locations
32. True
33. access time
34. True
35. electrically erasable
36. True
37. DRAM
38. SRAM
39. DRAM and SRAM
40. (c)
41. (c)
42. (a) 32Kx8, 256K
(f) 8Kx1, 8K
(b) 8Kx8, 64K
(g) 4Kx8, 32K
(c) 4Kx8, 32K
(h) 2Kx8, 16K
(d) 8Kx8, 64K
(i) 256Kx4, 1M
(e) 4Mx1, 4M
(j) 64Kx8, 512K
43. (a) 128K 14 8
(f) 256K 8 4
(b) 256K 15 8
(g) 8M 20 8
(c) 512K 16 8
(h) 16M 11 4
(d) 2M 18 8
(i) 512K 16 8
(e) 512K 16 8
44. 4000h - 7FFFh
45.
A0
A11
A12
A13
1
3
1
2
2
~CS
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
9
46. 8000h - 8FFFh, B000h - BFFFh, E000 – EFFFh
47.
A0
8kx8
A12
U?
A13
A14
A15
Vcc
1
2
3
6
4
5
A
B
C
G1
G2AN
G2BN
Y0N
Y1N
Y2N
Y3N
Y4N
Y5N
Y6N
Y7N
15
14
13
12
11
10
9
7
~CS
74138
Each controls 8K bytes block
48. 6000h - 7FFFh, C000h - DFFFh, E000h – FFFFh
49.
A0
32kx8
A14
U?
A15
A16
A17
Vcc
1
2
3
6
4
5
A
B
C
G1
G2AN
G2BN
Y0N
Y1N
Y2N
Y3N
Y4N
Y5N
Y6N
Y7N
15
14
13
12
11
10
9
7
~CS
74138
Each controls 32K bytes block
50. 4000h - 7FFFh, 8000h - BFFFh, C000h – FFFFh
SECTION 0.4: CPU AND HARVARD ARCHITECTURE
51. PC ( Program Counter )
52. ALU is responsible for all arithmetic and logic calculations in the CPU.
53. Address, control and data
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
10
CHAPTER 1: THE AVR MICROCONTROLLERS: HISTORY AND
FEATURES
SECTION 1.1: MICROCONTROLLERS AND EMBEDDED PROCESSORS
1.
2.
3.
4.
5.
6.
7.
8.
9.
False.
True.
True.
True.
CPU, RAM, ROM, EEPROM, I/O, Timer, Serial COM port, ADC.
RAM and ROM.
Keyboard, mouse, printer.
Computing power and compatibility with millions and millions of PCs.
PIC 16x – Microchip Technology, 8051 - Intel, AVR – Atmel, Z8 – Zilog,
68HC11 – Freescale Semiconductor (Motorola).
10. 8051.
11. Power consumption.
12. The ROM area is where the executable code is stored.
13. Very, in case there is a shortage by one supplier.
14. Suppliers other than the manufacturer of the chip.
15. B is absolutely wrong; 16 bit software can not run on an 8 bit system due to
special instructions and registers. But A can be true (in the case of software
compatibility).
SECTION 1.2: OVERVIEW OF THE AVR FAMILY
16. Flash memory is ideal for fast development because Flash memory can be erased
in seconds compared to 20 minutes or more needed for the UV-EPROM.
17. 32 pins
18. 32 Kbytes
19. 256 bytes
20. 8
21. 4K
22. 6
23. 2K
24. ATtiny11, ATtiny12, ATting15L
25. All AVRs have Flash ROM; but a few of them, like ATtiny20, ATtiny28L, and
ATtiny4 have no EEPROM
26. AT90USB1286, AT90USB1287, AT90USB162, AT90USB646, AT90USB647,
AT90USB82
27. AT90CAN128, AT90CAN32, AT90CAN64
28.
Program ROM Data RAM
(a) ATmega32 32 Kbytes
2048
(b) ATtiny44
2 Kbytes
128
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
11
(c) ATtiny84
8 Kbytes
(d) 90CAN128 128 Kbytes
512
4K
29.
Program ROM Data RAM
ATmega32 32 Kbytes
2048
ATmega16 16 Kbytes
1024
30.
EEPROM
1024
512
512
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
12
CHAPTER 2: AVR ARCHITECTURE & ASSEMBLY LANGUAGE
PROGRAMMING
SECTION 2.1: THE GENERAL PURPOSE REGISTERS IN THE AVR
1.
2.
3.
4.
5.
6.
7.
8.
8
8
8
0xFF
$28 – in R20
(a), (c), (d), (e), (g)
(c)
This is an illegal instruction since the arguments of ADD should be register. If they
instruction was valid 0x44 would be stored in R19
9. This is an illegal instruction since the arguments of ADD should be register. If they
instruction was valid 0xFF would be stored in R21
10. True
SECTION 2.2: THE AVR DATA MEMORY
11.
12.
13.
14.
15.
16.
17.
internal SRAM
True
True
False
False
data memory
data memory = general purpose register + I/O registers + SRAM. All AVRs have 32
general purpose registers. AVRs with less than 32 I/O pins, which are not a member of
special purpose AVR, have 64 I/O registers. The size of SRAM can be found in figures of
Chapter 1.
(a) 32 + 64 + 2048 = 2144
(b) 32 + 64 + 1024 = 1120
(c) 32 + 64 + 256 = 352
18. EEPROM does not lose its data when power is off, whereas SRAM does. So, the
EEPROM is used for storing data that should rarely be changed and should not be lost
when the power is off (e.g., options and settings); whereas the SRAM is used for storing
data and parameters that are changed frequently.
19. Yes
20. No, each microcontroller should have general purpose registers and I/O registers.
21. From $60 to $FFFF
22. 65,536 bytes
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
13
SECTION 2.3: USING INSTRUCTIONS WITH THE DATA MEMORY
23.
LDI
STS
LDI
STS
R20, $30
$105, R20
R20, $97
$106, R20
LDI
STS
STS
STS
STS
STS
STS
STS
STS
STS
R20, $55
$300, R20
$301, R20
$302, R20
$303, R20
$304, R20
$305, R20
$306, R20
$307, R20
$308, R20
24.
25.
LDI R16, $5F
OUT PORTB, R16
26. True
27.
LDI
STS
STS
STS
STS
STS
STS
R30, $11
$100, R30
$101, R30
$102, R30
$103, R30
$104, R30
$105, R30
LDS
LDS
ADD
LDS
ADD
LDS
ADD
LDS
ADD
LDS
ADD
R20,
R16,
R20,
R16,
R20,
R16,
R20,
R16,
R20,
R16,
R20,
LDI
STS
STS
STS
STS
STS
STS
R30, $11
$100, R30
$101, R30
$102, R30
$103, R30
$104, R30
$105, R30
$100
$101
R16
$102
R16
$103
R16
$104
R16
$105
R16
28.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
14
LDS
LDS
ADD
LDS
ADD
LDS
ADD
LDS
ADD
LDS
ADD
R20,
R16,
R20,
R16,
R20,
R16,
R20,
R16,
R20,
R16,
R20,
$100
$101
R16
$102
R16
$103
R16
$104
R16
$105
R16
STS $105, R20
29.
LDI R16, $15
STS $67, R16
LDI
LDS
ADD
ADD
ADD
ADD
ADD
R19,
R20,
R19,
R19,
R19,
R19,
R19,
0
$67
R20
R20
R20
R20
R20
30.
LDI R16, $15
STS $67, R16
LDI
LDS
ADD
ADD
ADD
ADD
ADD
R19,
R20,
R19,
R19,
R19,
R19,
R19,
0
$67
R20
R20
R20
R20
R20
STS $67, R19
31.
LDُ
S R27, $68
ُ
COM R27
32.
LDُ
S R19, $68
ُ
OUT PORTC, R19
SECTION 2.4: AVR STATUS REGISTER
33. 8
34. 0, 5
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
15
35.
36.
37.
38.
3, 2
When there is a carry beyond the D7 bit.
When there is a carry from the D3 to the D4 bit.
C = 1 because there is a carry beyond the D7 bit.
Z = 1 because the R20 (the result) has value 0 in it after the addition.
39.
(a)
$54
0101 0100
$C4
1100 0100
$118
10001 1000
C = 1 because there is a carry beyond the D7 bit.
+
R20 = $18
(b)
$00
0000 0000
$FF
1111 1111
$FF
1111 1111
C = 0 because there is no carry beyond the D7 bit.
+
R23 = $FF
(c)
$FF
1111 1111
$05
0000 0101
$FF
10000 0100
C = 1 because there is a carry beyond the D7 bit.
+
R30 = $04
40.
LDI
LDI
ADD
ADD
ADD
ADD
ADD
R16,
R20,
R16,
R16,
R16,
R16,
R16,
$55
$55
R20
R20
R20
R20
R20
SECTION 2.5: AVR DATA FORMAT AND DIRECTIVES
41.
.EQU
.EQU
.EQU
.EQU
.EQU
.EQU
.EQU
.EQU
.EQU
.EQU
.EQU
.EQU
MYDAT_1 = $37
MYDAT_2 = $62
MYDAT_3 = $47
MYDAT_4 = $50
MYDAT_5 = $C8
MYDAT_6 = $41
MYDAT_7 = $AA
MYDAT_8 = $FF
MYDAT_9 = $90
MYDAT_10 = $7E
MYDAT_11 = $0A
MYDAT_12 = $0F
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
16
42.
.EQU
.EQU
.EQU
.EQU
.EQU
.EQU
DAT_1
DAT_2
DAT_3
DAT_4
DAT_5
DAT_6
=
=
=
=
=
=
$16
$56
$99
$20
$F6
$FB
43.
.EQU
.EQU
.EQU
.EQU
.EQU
.EQU
TEMP0
TEMP1
TEMP2
TEMP3
TEMP4
TEMP5
=
=
=
=
=
=
$60
$61
$62
$63
$64
$65
LDI
STS
STS
STS
STS
STS
STS
R16, $11
TEMP0, R16
TEMP1, R16
TEMP2, R16
TEMP3, R16
TEMP4, R16
TEMP5, R16
LDS
LDS
ADD
LDS
ADD
LDS
ADD
LDS
ADD
LDS
ADD
R20,
R21,
R20,
R21,
R20,
R21,
R20,
R21,
R20,
R21,
R20,
TEMP0
TEMP1
R21
TEMP2
R21
TEMP3
R21
TEMP4
R21
TEMP5
R21
SECTION 2.6: INSTRUCTION TO AVR ASSEMBLY PROGRAMMING AND
SECTION 2.7: ASSEMBLING AN AVR PROGRAM
44.
45.
46.
47.
48.
49.
50.
51.
Low, High
Assembly
Assembler
True
False
False
No
Because they do not produce machine instructions. They just give directions to the
assembler.
52. True
53. hex
54. hex, eep, lst, map, and obj
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
17
SECTION 2.8: THE PROGRAM AND PROGRAM ROM SPACE IN THE AVR
55. 0
56. It executes whatever is at location 0 which could be garbage in this case.
57.
a) 2 bytes
b) 2 bytes
c) 2 bytes
d) 2 bytes
e) 2 bytes
f) 2 bytes
g) 2 bytes
h) 4 bytes
58. (a)
LDI
STS
LDI
STS
LDI
STS
LDI
STS
LDI
STS
R20,‘1’
0x100, R20
R20,‘9’
0x101, R20
R20,‘5’
0x102, R20
R20,‘1’
0x103, R20
R20,‘2’
0x104, R20
(b)
LDI
LDS
ADD
LDS
ADD
LDS
ADD
LDS
ADD
LDS
ADD
STS
R19,0
R16, 0x100
R19,R16
R16, 0x101
R19,R16
R16, 0x102
R19,R16
R16, 0x103
R19,R16
R16, 0x104
R19,R16
0x306, R19
(c)
59. In AVR, each location of the program memory holds 2 bytes; therefore:
a) Memory locations = 32 K / 2 = 16 K = 16 * 1024 = 16384 Î Last location = 16383
= $3FFF
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
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60.
61.
62.
63.
b) Memory locations = 8 K / 2 = 4 K = 4 * 1024 = 4096 Î Last location = 4095 = $FFF
c) Memory locations = 64 K / 2 = 32 K = 32 * 1024 = 32768 Î Last location = 32767
= $7FFF
d) Memory locations = 16 K / 2 = 8 K = 8 * 1024 = 8192 Î Last location = 8191 =
$1FFF
e) Memory locations = 128 K / 2 = 64 K = 64 * 1024 = 65536 Î Last location = 65535
= $FFFF
In ATmega32, the program memory is 32K bytes. Since the 32K is organized as 16K x 2
Bytes, the last location has the address of $3FFF. Therefore the program counter can have
values between 0 and $3FFF.
$7FFF = 32767 Î the program memory has 32767 + 1 = 32768 locations. Therefore, it
has 65536 = 64K bytes.
$3FF = 1023 Î the program memory has 1024 locations. Therefore, the size of program
memory is 2 Kbytes.
(a) $1FFF + 1 = 8,192 words = 16,384 bytes = 16 KB
(b) $3FFF + 1 = 16,384 words = 32 KB
(c) $7FFF + 1 = 32,768 words = 64 KB
(d) $FFFF + 1 = 65,536 words = 128 KB
(e) $1FFFF + 1 = 131,072 words = 256 KB
(f) $3FFFF + 1 = 262,144 words = 512 KB
(g) $FFF + 1 = 4096 words = 8 KB
(h) $1FF + 1 = 512 words = 1 KB
64. (a) $3FF + 1 = 1024 words = 2 KB
(b) $7FF + 1 = 2048 words = 4 KB
(c) $7FFFF + 1 = 524,288 words = 1,048,576 KB
(d) $FFFFF + 1 = 1,048,576 words = 2048 KB = 2 MB
(e) $1FFFFF + 1 = 2,097,152 words = 4096 KB = 4 MB
(f) $3FFFFF + 1 = 4,194,304 words = 8192 KB = 8 MB
(g) $5FFF + 1 = 24,576 words = 49152 bytes = 48 KB
(h) $BFFFF + 1 = 786,432 words = 1,572,864 bytes = 1536 KB = 1.5 MB
65. 2 bytes
66. 2 bytes
67. As shown in Figure 2-14, 8 bits are set aside for K. Therefore, K can be between 0 and
255.
68. $0C01 = 0000 1100 0000 0001. According to the figures of page 92, it is the machine
code for the ADD instruction.
69. It is a 4-byte instruction. 16 bits of it are set aside for K. Therefore, K can be between 0
and 65535. In AVR, the data memory is 64 KB; as a result, STS can address the entire
memory space.
70. It is a 4-byte instruction. 16 bits of it are set aside for K. Therefore, K can be between 0
and 65535. In AVR, the data memory is 64 KB; as a result, LDS can address the entire
memory space.
71. In the JMP instruction, 22 bits are set aside for K. Therefore K can be between 0 and
4,194,303.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
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SECTION 2.9: RISC ARCHITECTURE IN THE AVR
72. RISC is reduced instruction set computer; CISC stands for complex instruction set
computer.
73. CISC
74. RISC
75. RISC
76. CISC
77. False
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
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CHAPTER 3: BRANCH, CALL AND TIME DELAY LOOP
SECTION 3.1: BRANCH INSTRUCTIONS AND LOOPING
1.
2.
3.
4.
5.
6.
256
The instruction following the jump
PC
Relative jump, 2
4
RJMP is 2 byte whereas JMP is 4 bytes. Therefore RJMP uses less memory
location.
7. False
8. False
9. a, b, and d
10. The RJMP instruction is a 2-byte instruction. Of the 16 bits, the first 4 bits are set
aside for the opcode and the other 12 bits are used for the address of the
destination (operand). The operand can be between -2048 and 2047.
11. True
12.
LDI
BEGIN:LDI
HERE:
DEC
BRNE
DEC
BRNE
R20, 10
R21, 100
R21
HERE
R20
BEGIN
13.
L1:
L2:
L3:
LDI
LDI
LDI
R20, 10
R21, 100
R22, 100
DEC
BRNE
DEC
BRNE
DEC
BRNE
R22
L3
R21
L2
R20
L1
14. 200 * 100 = 20,000 times
15. Negative
16. Positive
SECTION 3.2: CALL INSTRUCTIONS AND STACK
17. 4
18. 2
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
21
19. False
20. True
21. In the AVRs whose program counter is not longer than 16 bits, 2 bytes are pushed
into the stack. In the AVRs whose program counters are longer than 16 bits, 3
bytes are pushed.
22. In the AVRs whose program counter is not longer than 16 bits, 2 bytes are pushed
into the stack. In the AVRs whose program counters are longer than 16 bits, 3
bytes are pushed.
23. 0
24. When the RET instruction at the end of the subroutine is executed, the top
location of the stack is copied back to the program counter and the stack pointer is
incremented. As a result the CALL is loaded into the PC, and the instruction
below the CALL instruction is executed.
25. In AVR, the stack can be as big as the internal RAM.
26. When a subroutine is called, the address of the instruction just below the CALL
instruction is pushed onto the stack.
SECTION 3.3: AVR TIME DELAY AND INSTRUCTION PIPELINE
27. crystal frequency = 1 / machine cycle = 1 / 1.25 µs = 0.8 MHz.
28. machine cycle = 1 / 20 MHz = 0.05 µs
29. machine cycle = 1 / 10 MHz = 0.1 µs
30. machine cycle = 1 / 16 MHz = 0.0625 µs
31. False
32.
LDI
BACK: LDI
HERE: NOP
DEC
BRNE
DEC
BRNE
Machine Cycle
R16, 200
1
R18, 100
1
1
R18
1
HERE 2/1
R16
1
BACK 2/1
1 + (1 + (1 + 1 + 2) × 100 – 1 + 1 + 2) × 200 – 1 = 1 + (1 + 400 + 2) × 200 = 1 +
403 × 200 – 1 = 80,600 machine cycles
80,600 × 0.125 µs = 10075 µs = 10.075 ms
33.
LDI
BACK: LDI
HERE: NOP
NOP
DEC
BRNE
DEC
BRNE
Machine Cycle
R20, 200
1
R22, 100
1
1
1
R22
1
HERE 2/1
R20
1
BACK 2/1
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
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1 + (1 + (1 + 1 + 1 + 2) × 100 – 1 + 1 + 2) × 200 – 1 = 1 + (1 + 500 + 2) × 200 = 1
+ 503 × 200 – 1 = 100,600 machine cycles
100,600 × 0.125 µs = 12575 µs = 12.575 ms
34.
LDI
BACK: LDI
HERE: NOP
DEC
BRNE
DEC
BRNE
Machine Cycle
R20, 200
1
R21, 250
1
1
R21
1
HERE 2/1
R20
1
BACK 2/1
1 + (1 + (1 + 1 + 2) × 250 – 1 + 1 + 2) × 200 – 1 = (1 + 1000 + 2) × 200 = 1003 ×
200 = 200,600 machine cycles
Instruction cycle = 1 / 4 MHz = 0.25 µs
200600 × 0.25 µs = 50150 µs = 50.150 ms
35.
LDI
BACK: LDI
NOP
NOP
NOP
HERE: DEC
BRNE
DEC
BRNE
Machine Cycle
R20, 200
1
R25, 100
1
1
1
1
R25
1
HERE 2/1
R20
1
BACK 2/1
1 + (1 + 1 + 1 + 1 + (1 + 2) × 100 – 1 + 1 + 2) × 200 – 1 = 1 + (4 + 300 + 2) × 200
– 1 = 61,200 machine cycles
Instruction cycle = 1 / 10 MHz = 0.1 µs
61200 × 0.1 µs = 6120 µs = 6.12 ms
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
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CHAPTER 4: AVR I/O PORT PROGRAMMING
SECTION 4.1: I/O PORT PROGRAMMING IN AVR
1. 40 pins
2. 2 pins are assigned to VCC: VCC and AVCC; and 2 pins are assigned to GND: GND
and AGND.
3. 32 pins
4. 8 pins (pins 33-40)
5. 8 pins (pins 1-8)
6. 8 pins (pins 22-29)
7. 8 pins (pins 14-21)
8. input
9. The DDRx register is used for the purpose of making a given port an input or output
port. The contents of PORTx registers determine the value of each port when it is
output.
10.
.INCLUDE "M32DEF.INC"
LDI R20, 0x00
OUT DDRC, R20
LDI R20,0xFF
OUT DDRB, R20
OUT DDRD, R20
AGAIN:
IN R20, PINC
OUT PORTB, R20
OUT PORTD, R20
JMP AGAIN
11.
.INCLUDE "M32DEF.INC"
LDI R20, 0x00
OUT DDRD, R20
LDI R20,0xFF
OUT DDRB, R20
OUT DDRC, R20
AGAIN:
IN R20, PIND
OUT PORTB, R20
OUT PORTC, R20
JMP AGAIN
12. pins 14 and 15
13.
Port
DDRA
DDRB
DDRC
Address
$3A
$37
$34
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
24
14.
(a)
.INCLUDE “M32DEF.INC”
LDI
R16, 0xFF
OUT
DDRB, R16
OUT
DDRC, R16
L1:
LDI
R16, 0xAA
OUT
PORTB, R16
OUT
PORTC, R16
LDI
R16, 0x55
OUT
PORTB, R16
OUT
PORTC, R16
RJMP L1
(b)
.INCLUDE “M32DEF.INC”
LDI
R16, 0xFF
OUT
DDRB, R16
OUT
DDRC, R16
LDI
R16, 0xFF
OUT
PORTB, R16
OUT
PORTC, R16
L1:
COM
R16
OUT
PORTB, R16
OUT
PORTC, R16
RJMP L1
SECTION 4.2: I/O BIT MANIPULATION PROGRAMMING
15. In ATmega32, all ports are bit addressable.
16. The advantage of the bit addressing is that it allows each bit to be modified without
affecting the other bits.
17. COM PORTB is invalid because AVR ports are not read-modify-write.
18.
.INCLUDE “M32DEF.INC”
SBI
DDRB, 2
SBI
DDRB, 5
L1:
SBI
PORTB, 2
SBI
PORTB, 5
CBI
PORTB, 2
CBI
PORTB, 5
RJMP L1
19.
.INCLUDE “M32DEF.INC”
SBI
DDRD, 3
SBI
DDRD, 7
SBI
DDRC, 5
L1:
SBI
PORTD, 3
SBI
PORTD, 7
SBI
PORTC, 5
CBI
PORTD, 3
CBI
PORTD, 7
CBI
PORTC, 5
RJMP L1
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
25
20.
.INCLUDE “M32DEF.INC”
LDI
R16,0xFF
OUT
DDRD,R16
CBI
DDRC, 3
L1:
SBIS PINC, 3
RJMP L1
LDI
R16,0x55
OUT
PORTD,R16
HERE: RJMP HERE
21.
.INCLUDE “M32DEF.INC”
LDI
R16,0xFF
OUT
DDRC,R16
CBI
DDRB, 7
L1:
SBIC PINB, 7
RJMP L1
HERE: LDI
R16,0x55
OUT
PORTC,R16
LDI
R16,0xAA
OUT
PORTC,R16
RJMP HERE
22.
.INCLUDE “M32DEF.INC”
LDI
R16,0xFF
OUT
DDRB,R16
CBI
DDRA, 0
L1:
SBIS PINA, 0
RJMP L2
LDI
R16,0x99
OUT
PORTB,R16
RJMP L1
L2:
LDI
R16,0x66
OUT
PORTB,R16
RJMP L1
;when PA0 is low the line is executed
;when PA0 is high the line is executed
23.
.INCLUDE “M32DEF.INC”
CBI
DDRB, 5
SBI
DDRB, 3
L1:
SBIS PINB, 5
RJMP L1
CBI
PORTB,3
SBI
PORTB,3
CBI
PORTB,3
L2:
RJMP L2
;jump L1 while PB5 is low
;when PB5 is high the line is executed
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
26
24.
.INCLUDE “M32DEF.INC”
CBI
DDRC, 3
SBI
DDRC, 4
L1:
SBIS PINC, 3
RJMP L2
SBI
PORTC, 4
RJMP L1
L2:
CBI
PORTC, 4
RJMP L1
;PC3 as input
;PC4 as output
;jump L1 while PC3 is low
;when PC3 is high the line is executed
25.
Make PD6 and
PD7 input
CBI
CBI
DDRD, 6
DDRD, 7
Make PC0 and
PC7 output
SBI
SBI
DDRC, 0
DDRC, 7
Yes
Is PD6 one
L1:
SBIS PIND, 6
No
Jump to
PD6_LOW
RJMP PD6_LOW
Set PC0
SBI PORTC, 0
RJMP L2
Clear PC0
Yes
Is PD7 one
PD6_LOW: CBI PORTC, 0
L2:
SBIS PIND, 7
No
Jump to
PD7_LOW
Set PC7
Clear PC7
RJMP PD7_LOW
SBI
RJMP
PD7_LOW: CBI
RJMP
PORTC, 7
L1
PORTC, 7
L1
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
27
.INCLUDE “M32DEF.INC”
CBI
DDRD, 6
CBI
DDRD, 7
SBI
DDRC, 0
SBI
DDRC, 7
L1:
SBIS PIND, 6
RJMP PD6_LOW
SBI
PORTC, 0
RJMP L2
PD6_LOW:
CBI
PORTC, 0
L2:
SBIS PIND, 7
RJMP PD7_LOW
SBI
PORTC, 7
RJMP L1
PD7_LOW:
CBI
PORTC, 7
RJMP L1
;PD6
;PD7
;PC0
;PC7
as
as
as
as
input
input
output
output
;jump PD6_LOW if PD6 is low
;when PD6 is high the line is executed
;jump L1 while PD7 is low
;when PD7 is high the line is executed
26.
.INCLUDE “M32DEF.INC”
CBI
DDRB, 5
CBI
DDRB, 6
LDI
R16, 0xFF
OUT
DDRC, R16
L1:
SBIC PINB, 5
RJMP L2
IS_LOW:
LDI
R16, 0x55
OUT
PORTC, R16
RJMP L1
L2:
SBIS PINB, 6
RJMP IS_LOW
LDI
R16, 0xAA
OUT
PORTC, R16
RJMP L1
;jump L2 if PB5 is high
;jump IS_LOW if PB6 is low
27.
.INCLUDE “M32DEF.INC”
CBI
DDRB, 5
CBI
DDRB, 6
LDI
R16, 0xFF
OUT
DDRC, R16
L1:
SBIS PINB, 5
RJMP L2
IS_HIGH:
LDI
R16, 0xAA
OUT
PORTC, R16
RJMP L1
L2:
SBIC PINB, 6
RJMP IS_HIGH
BOTH_LOW:
LDI
R16, 0x55
OUT
PORTC, R16
RJMP L1
28. 1001 1011 1011 0011
29. 1001 1010 1101 1010
;jump L2 if PB5 is low
;jump IS_HIGH if PB6 is high
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
28
CHAPTER 5: ARITHMETIC, LOGIC INSTRUCTIONS, AND
PROGRAMS
SECTION 5.1: ARITHMETIC INSTRUCTIONS
1. All the calculations are done in hexadecimal system.
(a)
3 F
+4 5
8 4
C = 0, Z = 0, H = 1
(b)
(c)
(d)
9 9
+5 8
F 1
C = 0, Z = 0, H = 1
1
+F F
+0 0
(1) 0 0
C = 1, Z = 1, H = 1
F F
+0 1
(1) 0 0
C = 1, Z = 1, H = 1
2.
LDI
LDI
ADD
R20,25
R21,10
R20,R21
LDI
LDI
ADD
LDI
ADC
R20,0x25
R21,0x19
R20,R21
R21,0x12
R20,R21
LDI
LDI
ADD
LDI
ADD
LDI
ADD
R20,0x25
R21,0x19
R20,R21
R21,0x12
R20,R21
R21,0x3D
R20,R21
(a)
Take 2’s complement of 0x12 (0001 0010):
Add to 0x23: 0010 0011
+ 1110 1110
1 0001 0001
Result = 0001 0001 = 0x11
3.
4.
5.
1110 1110
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
29
(b)
Take 2’s complement of 0x53 (0101 0011):
Add to 0x43: 0100 0011
+ 1010 1101
0 1111 0000
Result = 1111 0000 = 0xF0
(c)
99 decimal = 0x63 = 0110 0011
Take 2’s complement of 0x63 (0110 0011):
Add to 0x63: 0110 0011
+ 1001 1101
1 0000 0000
Result = 0000 0000 = 0x00
1010 1101
1001 1101
6.
(a)
LDI
SUBI
R20,0x23
R20,0X12
LDI
SUBI
R20,0x43
R20,0X53
LDI
SUBI
R20,99
R20,99
(b)
(c)
7.
LDI
LDI
LDI
LDI
ADD
ADC
R23,0x7F
R22,0x9A
R21,0xBC
R20,0x48
R20,R22
R21,R23
LDI
LDI
LDI
LDI
SUB
SBC
R23,0x7F
R22,0x9A
R21,0xBC
R20,0x48
R20,R22
R21,R23
LDI
LDI
MUL
R21,77
R20,34
R20,R21
;the result will be in R1:R0
LDI
LSR
LSR
R21,64
R21
R21
;divide the number by 2. R21 = 64/2 = 32
;divide the number by 3. R21 = 32/2 = 16
8.
9.
10.
11.
R1:R0
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
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SECTION 5.2: SIGNED NUMBER CONCEPTS AND ARITHMETIC
OPERATIONS
12.
(a) 1110 1001
(e) 1000 0000
(b) 0000 1100
(f) 0111 1111
(c) 1110 0100
(d) 0110 1111
13. unsigned
14.
(a)
LDI
LDI
ADD
R21,15
R20,-12
R20,R21
0000 1111 + 1111 0100 = (1)0000 0011
V = 0
LDI
LDI
ADD
R21,-123
R20,-127
R20,R21
1000 0101 + 1000 0001 = (1)0000 0110
V = 1
LDI
LDI
ADD
R21,+25
R20,+34
R20,R21
0010 0101 + 0011 0100 = (0)0101 1001
V = 0
LDI
LDI
ADD
R21,-127
R20,+127
R20,R21
1000 0001 + 0111 1111 = (1)0000 0000
V = 0
(b)
(c)
(d)
15. C flag is raised when there is a carry out of D7 of the result, but V flag is raised when there is
a carry from D6 to D7 and no carry out of D7 or when there is no carry from D6 to D7 and
there is a carry out of D7 of the result. C flag is used to indicate overflow in unsigned
arithmetic operations while V flag is involved in signed operations.
16. When there is a carry from D6 to D7 of result, but there is no carry out of D7 (C=0)
OR when there is no carry from D6 to D7 of result, but there is a carry out of D7
(C=1)
17. Status register
18. BRVS and BRVC instructions - BRCS and BRCC instructions
SECTION 5.3: LOGIC AND COMPARE INSTRUCTIONS
19.
(a) 0110 0101 AND 0111 0110 = 0110 0100 = 0x64
(b) 0111 0000 OR 0110 1011 = 0111 1011 = 0x7B
(c) 1001 0101 EXOR 1010 1010 = 0011 1111 = 0x3F
(d) 0101 1101 AND 0111 0101 = 0101 0101 = 0x55
(e) 1100 0101 OR 0001 0010 = 1101 0111 = 0xD7
(f) 0110 1010 EXOR 0110 1110 = 0000 0100 = 0x04
(g) 0011 0111 OR 0010 0110 = 0011 0111 = 0x37
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
31
20. BRSH is used after the compare instruction. If the unsigned binary number
represented in Rd was greater than or equal to the unsigned binary number
represented in Rr, then program execute a jump.
21. Yes.
22. both (a) and (b)
23. 0x85
SECTION 5.4: ROTATE AND SHIFT INSTRUCTIONS AND DATA
SERIALIZATION
24.
(a) 0 01010110 Æ 0 01100101 Æ C = 0 Æ 1 00110010 Æ 0 10011001 = 99h
(b) 0 0011 1001 Æ C = 1 Æ 0 0111 0011 Æ 0 11100110 = E6h
(c) C = 0 Æ 0 0100 1101 Æ 0 1101 0100 Æ 1 1010 1000 Æ 0 1101 0100 = D4h
(d) 0 0111 1010 Æ 0 0011 1101 = 3Dh
25.
(a)
LDI
MOV
ANDI
CLC
ROL
ROL
ROL
ROL
ANDI
CLC
ROL
ROL
ROL
ROL
ROL
OR
R20,0xFA
R21, R20
R20,0x0F
LDI
MOV
ANDI
CLC
ROR
ROR
ROR
ROR
ROR
ANDI
CLC
ROR
ROR
ROR
ROR
OR
R20,0xFA
R21, R20
R20,0x0F
R20
R20
R20
R20
R21,0xF0
R21
R21
R21
R21
R21
R20,R21
(b)
R20
R20
R20
R20
R20
R21,0xF0
R21
R21
R21
R21
R20,R21
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
32
26.
.INCLUDE "M32DEF.INC"
LDI
R20,0b10111001
LDI
R21, 8
;set a counter to 8
LDI
R22, 0
;set number of zeros to 0
AGAIN:ROL
R20
;move MSB to Carry
BRCC NEXT
;branch if no carry
INC
R22
;increment number of zeros
NEXT: DEC
R21
;decrement the counter
BRNE AGAIN
27.
LDI
LDI
AGAIN:ROR
BRCS
INC
CPI
BRNE
FIN:
R20, 0x68
R21, 0
R20
FIN
R21
R21,8
AGAIN
LDI
LDI
AGAIN:ROL
BRCS
INC
CPI
BRNE
FIN:
R20, 0x68
R21, 0
R20
FIN
R21
R21,8
AGAIN
;set a counter to 0
;move MSB to Carry
;branch if carry is one
;increment the counter
;Is there any other bit
;Jump AGAIN
;R21 is the position and is
;9 if there is no 1
28.
;set a counter to 0
;move MSB to Carry
;branch if carry is one
;increment the counter
;is there any other bit
;jump AGAIN
;R21 is the position and is
;9 if there is no 1
SECTION 5.5: BCD AND ASCII CONVERSION
29.
(a)
LDI
MOV
ANDI
ORI
MOV
SWAP
ANDI
ORI
R20,0x76
R21,R20
R21,0x0F
R21,0x30
R22,R20
R22
R22,0x0F
R22,0x30
;the packed BCD to be converted is 76
;R21 = R20 = 76H
;mask the upper nibble (R21 = 06H)
;make it ASCII (R21 = 39H)
;R22 = R20 = 76H
;swap nibbles (R22 = 67H)
;mask the upper nibble (R22 = 07)
;make it ASCII (R22 = 37H)
LDI
MOV
ANDI
ORI
MOV
SWAP
ANDI
ORI
R20,0x87
R21,R20
R21,0x0F
R21,0x30
R22,R20
R22
R22,0x0F
R22,0x30
;the packed BCD to be converted is 87
;R21 = R20 = 87H
;mask the upper nibble (R21 = 07H)
;make it ASCII (R21 = 37H)
;R22 = R20 = 87H
;swap nibbles (R22 = 78H)
;mask the upper nibble (R22 = 08)
;make it ASCII (R22 = 38H)
(b)
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
33
30.
LDI
LDI
ANDI
SWAP
R21,'3'
R22,'2'
R21,0x0F
R21
ANDI
OR
MOV
R22,0x0F
R22,R21
R20,R22
;load character 3 (0x33) to R21
;load character 2 (0x32) to R22
;mask upper nibble of R21
;swap nibbles of R21
;to make upper nibble of packed BCD
;mask upper nibble of R22
;join R22 and R21 to make packed BCD
;move the result to R20
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
34
CHAPTER 6: AVR ADVANCED ASSEMBLY LANGUAGE
PROGRAMMING
SECTION 6.1: INTRODUCING SOME MORE ASSEMBLER DIRECTIVES
1. R20 = (0x20 & 0x6F) | 0x14 = (0x20) | 0x14 = 0x34
R21 = 0x6F – (0x20 + 0x14) = 0x6F – 0x34 = 0x3B
2. R30 = LOW (0x100<<1) = LOW(0x200) = 00
R31 = HIGH (0x100<<1) = HIGH (0x200) = 0x2
R20 = 20
SECTION 6.2: REGISTER AND DIRECT ADDRESSING MODES
3. (b) and (c)
4. (a) I/O direct addressing
(c) Direct addressing
(e) two-register addressing
5.
Symbol
PORTB
PORTC
DDRC
DDRD
SPL
SPH
SREG
(b) Single register (immediate) addressing
(d) two-register addressing
I/O address
$18
$15
$14
$11
$3D
$3E
$3F
Data memory address
$38
$35
$34
$31
$5D
$5E
$5F
6.
7.
8.
9.
I/O direct
It stores the content of R20 in location 0xF0 of the data memory.
It loads the PORTC register with the contents of R19.
$60 to $085F
$60 + 2048 – 1 = 2143 = $085F
10. $60 to $045F
$60 + 1024 – 1 = 1119 = $45F
11.
.INCLUDE “M32DEF.INC”
LDI
R16, 6
LDI
R17, 9
ADD
R16, R17
LDI
R17, 2
ADD
R16, R17
LDI
R17, 5
ADD
R16, R17
LDI
R17, 7
ADD
R16, R17
STS
$200, R16
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
35
SECTION 6.3: REGISTER INDIRECT ADDRESSING MODE
12. X, Y, and Z
LDI XL, LOW(ourAddress)
LDI XH, HIGH(ourAddress)
LDI YL, LOW(ourAddress)
LDI YH, HIGH(ourAddress)
LDI ZL, LOW(ourAddress)
LDI ZH, HIGH(ourAddress)
13.
.INCLUDE "M32DEF.INC"
.EQU MEM_ADDR = 0x80
LDI
R16, 0xAA
LDI
R20, 0x20
LDI
XH, HIGH(MEM_ADDR)
LDI
XL, LOW(MEM_ADDR)
L1:
ST
X+, R16
DEC
R20
BRNE L1
L2:
RJMP L2
14.
.INCLUDE "M32DEF.INC"
.EQU MEM_ADDR = 0x90
LDI
R16, 0
LDI
R20, 0xA0
LDI
XH, HIGH(MEM_ADDR)
LDI
XL, LOW(MEM_ADDR)
L1:
ST
X+, R16
DEC
R20
BRNE L1
L2:
RJMP L2
15.
.INCLUDE "M32DEF.INC"
.EQU MEM_ADDR1 = 0x80
.EQU MEM_ADDR2 = 0x90
LDI
R20, 10
LDI
XH, HIGH(MEM_ADDR1)
LDI
XL, LOW(MEM_ADDR1)
LDI
YH, HIGH(MEM_ADDR2)
LDI
YL, LOW(MEM_ADDR2)
L1:
LD
R16,X+
ST
Y+, R16
DEC
R20
BRNE L1
L2:
RJMP L2
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
36
16.
.INCLUDE "M32DEF.INC"
.EQU MEM_ADDR = 0x80
LDI
R20, 0x10
LDI
XH, HIGH(MEM_ADDR)
LDI
XL, LOW(MEM_ADDR)
L1:
LD
R16, X
COM
R16
ST
X+, R16
DEC
R20
BRNE L1
L2:
RJMP L2
SECTION 6.4: LOOK-UP TABLE AND TABLE PROCESSING
17.
Location
200
201
202
203
204
205
206
207
208
209
High
byte
$61
$74
$00
$38
$2D
$35
$41
$45
$20
$38
Low
byte
$45
$72
$68
$39
$37
$36
$47
$42
$48
$39
18.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
37
Location
$340
$341
$342
High
byte
$56
$20
$FB
Low
byte
$22
$99
$F6
19. Z
LDI
ZH, HIGH(OUR_DATA<<1)
LDI
ZL, LOW(OUR_DATA<<1)
LPM
R20, Z
OUR_DATA: .DB “Our Data”
20. 16 bits, it can cover up to 64 kilobytes.
21.
.EQU
MEM_ADDR = 0x200
LDI
ZH, HIGH(MEM_ADDR<<1)
LDI
ZL, LOW(MEM_ADDR<<1)
LPM
R20, Z
.EQU
MEM_ADDR = 0x340
LDI
ZH, HIGH((MEM_ADDR<<1)|1)
LDI
ZL, LOW((MEM_ADDR<<1)|1)
LPM
R20, Z
22.
23.
.INCLUDE "M32DEF.INC"
.EQU RAM_ADDR = 0x60
LDI
R16, 0
LDI
R20, 0xA0
LDI
ZH, HIGH(MY_DATA<<1)
LDI
ZL, LOW(MY_DATA<<1)
LDI
XH, HIGH(RAM_ADDR)
LDI
XL, LOW(RAM_ADDR)
L1:
LPM
R16, Z+
ST
X+, R16
CPI
R16, 0
BRNE L1
L2:
RJMP L2
.ORG 0x600
MY_DATA: .DB
"1-800-999-9999", 0
24.
.INCLUDE "M32DEF.INC"
LDI
ZH, HIGH(LOOKUP<<1)
LDI
ZL, LOW(LOOKUP<<1)
ADD
ZL, R16
LPM
R20, Z
;R20 = y = R16^2 + 2*R16 + 5
HERE: RJMP HERE
.ORG 0x100
LOOKUP: .DB 5, 8, 13, 20, 29, 40, 53, 68, 85, 104
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
38
25.
.INCLUDE "M32DEF.INC"
LDI
LDI
ADD
LPM
HERE: RJMP
ZH, HIGH(LOOKUP<<1)
ZL, LOW(LOOKUP<<1)
ZL, R16
R20, Z
HERE
.ORG 0x100
LOOKUP: .DB 5, 25, 45, 65, 85, 105, 125, 145, 165, 185
26.
.INCLUDE "M32DEF.INC"
.EQU RAM_ADDR = 40
LDI
R16, 0
LDI
R20, 0xA0
LDI
ZH, HIGH(MY_DATA<<1)
LDI
ZL, LOW(MY_DATA<<1)
LDI
XH, HIGH(RAM_ADDR)
LDI
XL, LOW(RAM_ADDR)
L1:
LPM
R16, Z+
ST
X+, R16
CPI
R16, 0
BRNE L1
L2:
RJMP L2
.ORG 0x700
MY_DATA: .DB
"The earth is but one country", 0
27. True
28. False
29.
.INCLUDE "M32DEF.INC"
LDI
R16, 0xFF
OUT
DDRC, R16
LDI
R16, 0x00
OUT
DDRB, R16
LDI
ZH,HIGH(LOOKUP<<1)
L1:
LDI
ZL,LOW(LOOKUP<<1)
IN
R16, PINB
ANDI R16,0x0F
ADD
ZL,R16
LPM
R20,Z
OUT
PORTC, R20
RJMP L1
.ORG 0x100
LOOKUP: .DB
'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
39
SECTION 6.5: BIT-ADDRESSABILITY
30.
.INCLUDE "M32DEF.INC"
LDI
R16, HIGH(RAMEND)
OUT
SPH, R16
LDI
R16, LOW(RAMEND)
OUT
SPL, R16
SBI
DDRB, 5
L1:
SBI
PORTB, 5
CALL DELAY
CALL DELAY
CALL DELAY
CBI
PORTB, 5
CALL DELAY
RJMP L1
31.
.INCLUDE "M32DEF.INC"
LDI
R16, HIGH(RAMEND)
OUT
SPH, R16
LDI
R16, LOW(RAMEND)
OUT
SPL, R16
SBI
DDRC, 7
L1:
SBI
PORTC, 7
CALL DELAY
CALL DELAY
CALL DELAY
CALL DELAY
CBI
PORTC, 7
CALL DELAY
RJMP L1
32.
.INCLUDE "M32DEF.INC"
LDI
R16, HIGH(RAMEND)
OUT
SPH, R16
LDI
R16, LOW(RAMEND)
OUT
SPL, R16
CBI
DDRB, 4
SBI
DDRB, 7
L1:
SBIS PINB, 4
RJMP L1
SBI
PORTB, 7
CALL DELAY
CBI
PORTB, 7
CALL DELAY
RJMP L1
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
40
33.
.INCLUDE "M32DEF.INC"
LDI
R16, HIGH(RAMEND)
OUT
SPH, R16
LDI
R16, LOW(RAMEND)
OUT
SPL, R16
CBI
DDRC, 1
LDI
R20,0xFF
OUT
DDRD, R20
L1:
SBIC PINC, 1
RJMP L1
LDI
R20, 0x55
OUT
PORTD, R20
L2:
RJMP L2
34. SREG
35. bit 1
36.
a. valid, PB1
b. invalid, we should write CBI PORTC,3 instead
c. invalid
d. valid, bit 0 of R20
e. invalid
f. valid, bit 3 of R20 is stored in the T flag
g. invalid
h. valid, the N flag is cleared
37. valid
38. all of them
39. none of them
40. CLC
41. BRCS
42. BREQ
43. Bits 0, 1, 5, and 3 are assigned to C, Z, H, and V, respectively.
44. False, the lower 32 I/O registers are bit addressable.
45.
IN
BST
LDS
BLD
STS
R16, SREG
R16, SREG_C
R16, 0x60
R16, 4
0x60, R16
;T = C
;R16 = [0x60]
;R16.4 = T
;[0x60] = R16
IN
BST
LDS
BLD
STS
R16, SREG
R16, SREG_H
R16, 0x160
R16, 2
0x160, R16
;T = H
;R16 = [0x160]
;R16.2 = T
;[0x160] = R16
IN
BST
LDS
BLD
STS
R16, SREG
R16, SREG_Z
R16, 0x120
R16, 7
0x120, R16
;T = Z
;R16 = [$120]
;R16.7 = T
;[$120] = R16
46.
47.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
41
48.
MOV
R16, R20
ANDI R16, 0x03
CPI
R16, 0
BRNE ARE_NOT_LOW
ASR
R20
ASR
R20
ARE_NOT_LOW: …
49.
LDI
OUT
BST
BRTC
LDI
OUT
NOT_HIGH:
R20, 0xFF
DDRD, R20
R25, 7
NOT_HIGH
R20, 0xFF
PORTD, R20
50.
a.
LDI
OUT
R20, 0xFF
PORTC, R20
SBI
SBI
SBI
SBI
SBI
SBI
SBI
SBI
PORTC,
PORTC,
PORTC,
PORTC,
PORTC,
PORTC,
PORTC,
PORTC,
b.
0
1
2
3
4
5
6
7
51.
MOV
R20, R24
ANDI R20, 0x07
CPI
R20, 0
BRNE NOT_DIVISIBLE
DIVISIBLE: …
NOT_DIVISIBLE: …
SECTION 6.6: ACCESSING EEPROM IN AVR
52.
.INCLUDE "M32DEF.INC"
LDI
R20, HIGH(RAMEND)
OUT
SPH, R20
LDI
R20, LOW(RAMEND)
OUT
SPL, R20
L1:
LDI
LDI
LDI
LDI
RCALL
INC
R20, 0
R16, $30
XH, HIGH (EE_MEM)
XL, LOW (EE_MEM)
STORE_IN_EEPROM
XL
;loaded into EEPROM
;counter
;X points to location 0 of EEPROM
;store R20 in location X of EEPROM
;X points to next memory location
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
42
DEC
BRNE
HERE: RJMP
R16
L1
HERE
;decrement counter
;if R16 is not zero go to L1
STORE_IN_EEPROM:
SBIC EECR, EEWE
RJMP STORE_IN_EEPROM
OUT
EEARH, XH
OUT
EEARL, XL
OUT
EEDR, R20
SBI
EECR, EEMWE
SBI
EECR, EEWE
RET
.ESEG
.ORG 0
EE_MEM: .DB 0
53.
.INCLUDE "M32DEF.INC"
.EQU RAM_ARRAY
= 0x80
LDI
OUT
LDI
OUT
LDI
LDI
LDI
LDI
LDI
L1:
LD
RCALL
INC
DEC
BRNE
HERE: RJMP
R20,HIGH(RAMEND)
SPH,R20
R20,LOW(RAMEND)
SPL,R20
R16, 10
;counter
ZH, HIGH(RAM_ARRAY)
;Z points to RAM_ARRAY of RAM
ZL, LOW(RAM_ARRAY)
XH, HIGH(EE_MEM)
;X points to EE_MEM of EEPROM
XL, LOW(EE_MEM)
R20, Z+
STORE_IN_EEPROM
;store R20 in location X of EEPROM
XL
;X points to next memory location
R16
;decrement counter
L1
;if R16 is not zero go to L1
HERE
STORE_IN_EEPROM:
SBIC EECR, EEWE
RJMP STORE_IN_EEPROM
OUT
EEARH, XH
OUT
EEARL, XL
OUT
EEDR, R20
SBI
EECR, EEMWE
SBI
EECR, EEWE
RET
.ESEG
.ORG $10
EE_MEM: .DB 0
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
43
54.
.INCLUDE "M32DEF.INC"
.EQU RAM_ARRAY
= 0x80
LDI
R20,HIGH(RAMEND)
OUT
SPH,R20
LDI
R20,LOW(RAMEND)
OUT
SPL,R20
LDI
R16, 10
;counter
LDI
LDI
ZH, HIGH(RAM_ARRAY)
ZL, LOW(RAM_ARRAY)
;Z points to RAM_ARRAY of RAM
LDI
XH, HIGH(EE_MEM)
;X points to EE_MEM of EEPROM
LDI
XL, LOW(EE_MEM)
L1: RCALL LOAD_FROM_EEPROM ;load R20 with contents of location X
ST
Z+, R20
INC
XL
;X points to next memory location
DEC
R16
;decrement counter
BRNE L1
;if R16 is not zero go to L1
HERE: RJMP HERE
LOAD_FROM_EEPROM:
SBIC
RJMP
OUT
OUT
SBI
IN
RET
.ESEG
.ORG $10
EE_MEM: .DB
EECR, EEWE
LOAD_FROM_EEPROM
EEARH, XH
EEARL, XL
EECR, EERE
R20, EEDR
0
55.
.INCLUDE "M32DEF.INC"
LDI
R20, HIGH (RAMEND)
OUT
SPH, R20
LDI
R20, LOW (RAMEND)
OUT
SPL, R20
LDI
R16, $10
LDI
LDI
R17, 0
R18, 0
;counter
LDI
XH, HIGH ($10)
;X points to location $10 of EEPROM
LDI
XL, LOW ($10)
L1: RCALL LOAD_FROM_EEPROM ;load R20 with contents of location X
ADD
R17, R20
BRCC L2
INC
R18
L2:
INC
XL
;X points to next memory location
DEC
R16
;decrement counter
BRNE L1
;if R16 is not zero go to L1
HERE: RJMP HERE
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
44
LOAD_FROM_EEPROM:
SBIC
RJMP
OUT
OUT
SBI
IN
RET
EECR, EEWE
LOAD_FROM_EEPROM
EEARH, XH
EEARL, XL
EECR, EERE
R20, EEDR
SECTION 6.7: CKECKSUM AND ASCII SUBROUTINES
56.
Character H
Hex
48
e
65
l
6C
L
6C
o
6F
$48
+$65
+$6C
+$6C
+$6F
1 F4 Î dropping the carry of 1, we have $F4. Its 2’s complement is $0C.
Therefore, the checksum byte is $0C.
57.
a. $65 + $09 + $95 + $23 = 1 26 Î it is other than 0. Therefore it is corrupted.
b. $71 + $69 + $38 + $81 + $6D = 2 00 Î It is 0. Therefore, it is not corrupted.
58. True
59.
.include "m32def.inc"
.EQU
RAM_BUFFER = 0x80
LDI
OUT
LDI
OUT
L1:
R20,
SPH,
R20,
SPL,
LDI
LDI
HIGH (RAMEND)
R20
LOW (RAMEND)
R20
;Z points to OUR_DATA of Flash ROM
ZH, HIGH(OUR_DATA<<1)
ZL, LOW(OUR_DATA<<1)
LDI
LDI
XH, HIGH(RAM_BUFFER)
XL, LOW(RAM_BUFFER)
LPM
ST
CPI
BRNE
R20, Z+
X+, R20
R20, 0
L1
LDI
CALL
R16, 31
CAL_CHKSUM
;X points to RAM_BUFFER of RAM
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
45
LDI
CALL
TST
BREQ
CORRUPTED:
R16, 32
TEST_CHKSUM
R20
NOT_CORRUPTED
NOT_CORRUPTED:
L2:
RJMP
L2
;-------calculating checksum byte
CAL_CHKSUM:
LDI
YL,LOW(RAM_BUFFER)
LDI
YH,HIGH(RAM_BUFFER)
;Y points to RAM_BUFFER
LDI
R20,0 ;SUM = 0
CL1: LD
R17,Y+
;load R17 with contents of loc Y
ADD
R20,R17
;SUM = SUM + R17
DEC
R16
;Decrement COUNTER
BRNE CL1
;loop while COUNTER is not zero
NEG
R20
;two's complement SUM
ST
Y,R20
;Store checksum in loc Y of RAM
RET
;return
;-------testing checksum byte
TEST_CHKSUM:
LDI
YL,LOW(RAM_BUFFER)
LDI
YH,HIGH(RAM_BUFFER)
;Y points to RAM_OPTIONS
LDI
R20,0
;SUM = 0
TL1: LD
R17,Y+
;load R17 with contents of loc Y
ADD
R20,R17
;SUM = SUM + R17
DEC
R16
;Decrement COUNTER
BRNE TL1
;if COUNTER is not zero goto TL1
RET
OUR_DATA: .DB "Hello, my fellow world citizens", 0
60. ASCII
61.
.INCLUDE "M32DEF.INC"
.EQU
RAM_BUFFER = 0x140
L1:
LDI
LDI
LDI
LDI
ZH,
ZL,
XH,
XL,
HIGH(MYDATA<<1)
LOW(MYDATA<<1)
HIGH(RAM_BUFFER)
LOW(RAM_BUFFER)
LDI
LPM
MOV
R16, 4
R20, Z+
R21, R20
ANDI
ORI
ST
R20,0x0F
R20,0x30
X+,R20
SWAP
ANDI
ORI
R21
R21,0x0F
R21,0x30
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
46
L2:
ST
X+,R21
DEC
BRNE
RJMP
R16
L1
L2
.ORG
MYDATA:
$700
.DB
$76, $87, $98, $43
62.
.INCLUDE "M32DEF.INC"
.EQU RAM_BUFFER = 0x60
LDI
LDI
LDI
LDI
ZH,
ZL,
XH,
XL,
LDI
R16, 4
LPM
LPM
R20, Z+
R21, Z+
ANDI
ANDI
SWAP
OR
ST
R20,0x0F
R21,0x0F
R21
R20, R21
X+,R20
DEC
BRNE
RJMP
R16
L1
L2
.ORG $300
MYDATA:
.DB
L1:
L2:
HIGH(MYDATA<<1)
LOW(MYDATA<<1)
HIGH(RAM_BUFFER)
LOW(RAM_BUFFER)
"87675649"
63.
.INCLUDE "M32DEF.INC"
.DEF NUM = R20
.DEF DENOMINATOR = R21
.DEF QUOTIENT = R22
.EQU
ASCII_RESULT = 0x60
LDI
R20, HIGH (RAMEND)
OUT
SPH, R20
LDI
R20, LOW (RAMEND)
OUT
SPL, R20
LDI
LDI
XH,HIGH(ASCII_RESULT)
XL,LOW(ASCII_RESULT)
LDI
OUT
LDI
OUT
R16,0x00
DDRD, R16
R16,0xFF
PORTD, R16
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
47
NOP
IN
NUM,PIND
LDI
DENOMINATOR, 10
RCALL DIVIDE
ORI
NUM, 0x30
ST X+,NUM
MOV
NUM,QUOTIENT
RCALL DIVIDE
ORI
NUM, 0x30
ST
X+, NUM
ORI
QUOTIENT,0x30
ST
X+,QUOTIENT
L2:
RJMP
DIVIDE:
LDI
L1:
INC
SUB
BRCC
DEC
ADD
RET
L2
QUOTIENT,0
QUOTIENT
NUM, DENOMINATOR
L1
QUOTIENT
NUM,DENOMINATOR
SECTION 6.8: MACROS
64.
1) The programs using MACROs are more readable.
2) MACROs do not use stacks and are not at the risk of stack overflow in nested
form.
65. A MACRO - Because MACROs are replaced with their corresponding instructions in
assembling process.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
48
CHAPTER 7: AVR PROGRAMMING IN C
SECTION 7.1: DATA TYPES AND TIME DELAYS IN C
1.
(a) char
(d) unsigned char
(g) unsigned int
(b) unsigned char
(e) unsigned char
(h) unsigned char
2.
(a) $0E
(d) $07
(g) $FF
3.
(a) Crystal frequency
(b) The way the C compiler compiles (depends on the compiler type)
4.
Crystal frequency (also choice over compiler should be taken into consideration)
5.
No, that is an internal factor which is not under programmer’s control. It is determined
and designed by the IC designer.
6.
Because in the compilation of the C code into assembly, different compilers use different
methods based on their design and optimization which results in different hex file sizes.
(b) $18
(e) $20
(h) $0F
(c) unsigned int
(f) unsigned char
(i) array of unsigned char
(c) $41
(f) $45
SECTION 7.2: I/O PROGRAMMING IN C
7.
PORTC = 0x00 changes the value of Port C to 0x00 but DDRC = 0x00 changes
the direction of Port C to input.
8.
#include <avr/io.h>
#include <util/delay.h>
void main (void)
{
DDRB = 0xFF;
while (1)
{
PORTB = 0xAA ;
_delay_ms(200);
PORTB = 0x55;
_delay_ms(200);
}
}
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
49
9.
#include <avr/io.h>
#include <util/delay.h>
void main (void)
{
DDRB = 0xFF;
while (1)
{
PORTB = PORTB | (1<<1) | (1<<3);
_delay_ms(200);
PORTB = PORTB & ~ ((1<<1) | (1<<3));
_delay_ms(200);
}
}
10.
void delay100ms(void)
{
unsigned int j, i;
for (i=0 ; i< 450 ; i++)
for (j=0 ; j< 100 ; j++);
}
11.
#include <avr/io.h>
#include <util/delay.h>
void main (void)
{
DDRC = 0xFF;
while (1)
{
PORTC = PORTC | (1<<3);
_delay_ms(200);
PORTC = PORTC & ~ (1<<1);
_delay_ms(200);
}
}
12.
#include <avr/io.h>
#include <util/delay.h>
void main (void)
{
DDRB = 0xFF;
unsigned char i = 0;
while (1)
{
PORTB = i;
i ++;
if (i > 99)
i = 0;
}
}
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
50
SECTION 7.3: LOGIC OPERATIONS IN C
13.
a.
1111 0000
And
0100 0101
0100 0000 = 0x40
b.
1111 0000
And
0101 0110
0101 0000 = 0x50
c.
1111 0000
xor
0111 0110
1000 0110 = 0x86
d.
1111 0000
And
1001 0000
1001 0000 = 0x90
e.
1111 0000
Xor
1001 0000
0110 0000 = 0x60
f.
1111 0000
Or
1001 0000
1111 0000 = 0xF0
g.
1111 0000
And
1111 1111
1111 0000 = 0xF0
h.
1111 0000
Or
1001 1001
1111 1001 = 0xF9
i.
1111 0000
Xor
1110 1110
0001 1110 = 0x1E
j.
1111 0000
Xor
1010 1010
0101 1010 = 0x5A
14.
a. 0x65&0x76
0110 0101
And
0111 0110
0110 0100 = 0x64
b. 0x70|0x6B
0111 0000
Or
0110 1011
0111 1011 = 0x=7B
c. 0x95^0xAA
1001 0101
Xor
1010 1010
0011 1111 = 0x3F
d. 0x5D&0x78
0101 1101
And
0111 1000
0101 1000 = 0x58
e. 0xC5|0x12
1100 0101
Or
0001 0010
1101 0111 = 0xD7
f. 0x6A^0x6E
0110 1010
Xor
0110 1110
0000 0100 = 0x04
g. 0x37|0x26
0011 0111
Or
0010 0110
0011 0111 = 0x37
15.
a. 0x65>>2
0110 0101 >>2
0001 1001 = 0x19
b. 0x39<<2
0011 1001 <<2
1110 0100 = 0xE4
c. 0xD4>>3
1101 0100 >>3
0001 1010 = 0x1A
d. 0xA7<<2
1010 0111<<2
1001 1100 = 0x9C
16.
#include <avr/io.h>
unsigned char swap(unsigned char a)
{
unsigned char t= 0;
t = a & 0x0F;
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
51
}
t = t << 4;
a = a >> 4;
return ( a | t );
void main (void)
{
unsigned char i;
i = swap (0x95);
}
17.
unsigned char findZero(unsigned char a)
{
unsigned char i, count = 0;
for ( i = 0 ; i <8 ; i++)
{
if ( (a & 0x01) == 0 )
count ++ ;
a = a >> 1;
}
}
return ( count );
SECTION 7.4: DATA CONVERSION PROGRAMS IN C
18.
#include <avr/io.h>
//standard AVR header
int main(void)
{
unsigned char x, y;
unsigned char mybyte = 0x34;
DDRB = DDRC = 0xFF;
x = mybyte & 0x0F;
PORTB = x | 0x30;
y = mybyte & 0xF0;
y = y >> 4;
PORTC = y | 0x30;
}
//make port B and C output
//mask upper 4 bits
//make it ASCII
//mask lower 4 bits
//shift it to lower 4 bits
//make it ASCII
return 0;
19.
#include <avr/io.h>
//standard AVR header
int main(void)
{
unsigned char bcdbyte;
unsigned char w = '7';
unsigned char z = '2';
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
52
DDRB = 0xFF;
w = w & 0x0F;
w = w << 4;
z = z & 0x0F;
bcdbyte = w | z;
PORTB = bcdbyte;
}
//make Port B an output
//mask 3
//shift left to make upper BCD digit
//mask 3
//combine to make packed BCD
return 0;
20.
#include <avr/io.h>
//standard AVR header
int main(void)
{
unsigned char abyte = 0b01001101;
unsigned char i = 0 ;
unsigned char ones = 0;
while (abyte != 0 )
{
if ((abyte & 0x01 ) != 0)
ones ++ ;
abyte = abyte >> 1 ;
}
}
return 0;
SECTION 7.6: MEMORY ALLOCATION IN C
21.
22.
23.
24.
25.
(a) data SRAM (b) code space
(c) code space
(d) code space
False
1) saving data RAM space (this type of data usually needs a lot of space).
2) They are usually fixed. We use ROM to save fixed data and RAM to store variable
data.
1) Much more storage space
2) Not occupying RAM space which may be needed for storing some essential data
1) Data stored in ROM space can not be changed unless with re-programming.
2) The more code space we use for data, the less is left for instructions.
26.
#include <avr/io.h>
//Standard AVR header
void eepromWrite (unsigned int pos, unsigned char data )
{
while(EECR & (1<<EEWE));
//wait for last write to finish
}
EEAR
EEDR
EECR
EECR
= pos;
= data;
|= (1<<EEMWE);
|= (1<<EEWE);
//Write low byte to address register
//Write data to data register
//Write one to EEMWE
//Start eeprom write
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
53
int main(void)
{
unsigned char str[] = "Sarmad";
unsigned char i = 0;
while (str[i] != '\0')
{
eepromWrite(i,str[i]);
i++ ;
}
}
return 0;
27.
28.
29.
30.
(a) data SRAM
(b) data SRAM
(c) data SRAM
(d) data SRAM
(e) code space
1) Saving data RAM space (this type of data usually needs a lot of space).
2) They are usually fixed. We use ROM to save fixed data and RAM to store variable
data.
Occupying RAM space which may be needed for storing some essential data
It is not fixed and can be changed during the execution of the code
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
54
CHAPTER 8: AVR HARDWARE CONNECTION
SECTION 8.1: ATMEGA32 PIN CONNECTION
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
40 pin
pins 10 and 30 are assigned to VCC and pins 11 and 31 are assigned to GND
32
12 and 13
False
9
High, Low
2
2
True
input
8 (40 – 33)
8 (1 – 8)
8 (22 – 29)
8 (14 – 21)
Input
SECTION 8.2: AVR FUSE BITS
17.
18.
19.
20.
21.
22.
23.
24.
25.
5 (External RC Oscillator, External Clock, Crystal Oscillator, Low-Frequency
Crystal Resonator, Calibrated RC Oscillator
CKSEL3…0
External RC oscillator
Internal RC oscillator
Crystal oscillator
2 fuse bytes
BODLEVEL
BODEN
It means that the system will reset if the VCC level falls bellow 4V
SECTION 8.3: EXPLAINING THE INTEL HEX FILE FOR AVR
26.
27.
28.
29.
True
True
True
After ‘:’ the record starts with 10, which means that the data field contains 10 (16
decimal) bytes of data. The next field is the address field (0010), and it indicates that
the first byte of the data field will be placed in address location 16 in the current
segment. So the first byte of code will be loaded into location 0 of Flash memory.
The next field is the data field, which contains the code to be loaded into the chip.
The last field of the record is the checksum byte of the record. Notice that the
checksum byte at the end of each line represents the checksum byte for everything in
that line, and not just for the data portion.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
55
30.
31.
10+00+10+00+08+BB+0E+94+0C+00+FB+CF+40+E1+58+EC+6A+EF+00+00+E7
= 800. Dropping the 8 will leave 00. It shows that the information is not corrupted.
Extended Intel Hex files can be used for ROM size of more than 64 kilobytes
SECTION 8.4: AVR PROGRAMMIN AND TRAINER BOARD
32.
33.
34.
35.
True
True
Parallel programming, ISP (in circuit serial programming), Boot loader
False
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
56
CHAPTER 9: AVR TIMER PROGRAMMING IN ASSEMBLY AND C
SECTION 9.1: PROGRAMMING TIMERS 0, 1, AND 2
1. three timers
2. 8, TCNT0
3. 16, TCNT1H, TCNT1L
4. 1024
5. 1024
6. 8
7. It is used for control of Timer0.
8. False
9. False
10. TCCR0=00000001=0x01
11.
(a) frequency = 8 MHz
(b) frequency = 16 MHz
(c) frequency = 1 MHz
(d) frequency = 10 MHz
period = 1 / (8 MHz) = 0.125 µs
period = 1 / (16 MHz) = 0.0625 µs
period = 1 / (1 MHz) = 1 µs
period = 1 / (10 MHz) = 0.1 µs
12. TIFR
13. (a) $FF to $00 or 255 to 0
(b) $FFFF to $0000 or 65535 to 0
14. (a) When the timer reaches the value $FF and rolls over, the TOV0 flag is raised.
(b) When the timer reaches the value $FFFF and rolls over, the TOV1 flag is raised.
15. True
16. True
17. frequency = 8 MHz. Now with no prescaler, we have 8 MHz. The period is = 1 / 8 MHz =
0.125 µs. Now 20 µs/0.125 µs = 160. Therefore TCNT0 = 256 – 160 = 96
18. frequency = 8 MHz. The period is = 1 / 8 MHz = 0.125 µs. Now 5 ms/0.125 µs = 40,000.
The largest possible prescaler is 1024. 40,000 / 1024 = 39.
Therefore TCNT0 = 256 – 39 = 217.
19. frequency = 1 MHz. The period is = 1 / 1 MHz = 1 µs. Now 2.5 ms / 1 µs = 2,500. Therefore
TCNT1 = 65,536 – 2,500 = 63,036.
20. frequency = 1 MHz. The period is = 1 / 1 MHz = 1 µs. Now 0.2 ms / 1 µs = 200. Therefore
OCR0 = 200 – 1 = 199.
21. frequency = 1 MHz. The period is = 1 / 1 MHz = 1 µs. Now 2 ms / 1 µs = 2000. Therefore
OCR1 = 2000 – 1 = 1999.
22. frequency = 8 MHz. Now with prescaler of 1024, we have 8 MHz / 1024 = 7812.5 Hz. The
period is = 1 / 7812.5 Hz = 0.128 ms. Now t = 0.128 ms × 65536 = 8.388608. Therefore the
lowest frequency = 1 / T = 1/2t = 1/16.777216 = 0.0596 Hz
23. frequency = 8 MHz. Now, with the prescaler of 1, we have 8MHz/1 = 8MHz. The period is
1 / 8 MHz = 0.125 µs. Now, the highest Freq = 1 / (2 x 0.125 µs x 1) = 4 MHz.
24. frequency = 8 MHz. Now with prescaler of 1024, we have 8 MHz / 1024 = 7812.5 Hz. The
period is = 1 / 7812.5 Hz = 0.128 ms. Now t = 0.128 ms × 256 = 32.768 ms. Therefore the
lowest frequency = 1 / T = 1/2t = 1/ 65.536 = 15.259 Hz
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
57
frequency = 8 MHz. Now, with the prescaler of 1, we have 8MHz/1 = 8MHz. The period is
1 / 8 MHz = 0.125 µs. Now, the highest Freq = 1 / (2 x 0.125 µs x 1) = 4 MHz.
25. $F2, $F3, $F4, $F5, $F6, $F7, $F8, $F9, $FA, $FB, $FC, $FD, $FE, $FF, $00
15 states
26. 1 / 1 kHz = 1 ms. Now 1 ms / 2 = 500 µs.
Scaler
None
8
64
256
1024
Timer Clock
8 MHz
8 MHz/8 = 1 MHz
8 MHz / 64 = 125 kHz
8 MHz / 256 = 31.25 kHz
8 MHz / 1024 = 7812.5 Hz
Timer Period
1 / 8 MHz = 0.125 µs
1 / 1 MHz = 1 µs
1 / 125 kHz = 8 µs
1 / 31.25 kHz = 32 µs
1 / 7812.5 Hz = 128 µs
Timer value
500 µs / 0.125 µs = 4000
500 µs / 1 µs = 500
500 µs / 8 µs = 62.5
500 µs / 32 µs = 15.62
500 µs / 128 µs = 3.9
.INCLUDE "M32DEF.INC"
L1:
LDI
OUT
LDI
OUT
R20,
SPH,
R20,
SPL,
SBI
SBI
CALL
CBI
CALL
RJMP
DDRB, 0
PORTB, 0
DELAY
PORTB, 0
DELAY
L1
DELAY:LDI
OUT
LDI
OUT
LDI
OUT
DELAY_L1:
IN
SBRS
RJMP
LDI
OUT
LDI
OUT
RET
HIGH(RAMEND)
R20
LOW(RAMEND)
R20
R20, -62
TCNT0, R20
R20, (1<<TOV0)
TIFR, R20
R20, 0x03
TCCR0, R20
R20,TIFR
R20, TOV0
DELAY_L1
R20, 0
TCCR0, R20
R20, (1<<TOV0)
TIFR, R20
27. 1 / 3 kHz = 0.333 ms = 333 µs. Now 333 µs / 2 = 166.5 µs.
Scaler
None
8
64
256
1024
Timer Clock
8 MHz
8 MHz/8 = 1 MHz
8 MHz / 64 = 125 kHz
8 MHz / 256 = 31.25 kHz
8 MHz / 1024 = 7812.5 Hz
Timer Period
1 / 8 MHz = 0.125 µs
1 / 1 MHz = 1 µs
1 / 125 kHz = 8 µs
1 / 31.25 kHz = 32 µs
1 / 7812.5 Hz = 128 µs
Timer value
166.5 µs / 0.125 µs = 1332
166.5 µs / 1 µs = 166.5
166.5 µs / 8 µs = 20.8
166.5 µs / 32 µs = 15.62
166.5 µs / 128 µs = 3.9
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
58
.INCLUDE "M32DEF.INC"
LDI
R20, HIGH(RAMEND)
OUT
SPH, R20
LDI
R20, LOW(RAMEND)
OUT
SPL, R20
SBI
DDRB, 0
L1:
SBI
PORTB, 0
CALL DELAY
CBI
PORTB, 0
CALL DELAY
RJMP L1
DELAY:
LDI
OUT
LDI
OUT
LDI
OUT
LDI
OUT
LDI
OUT
DELAY_L1:
IN
SBRS
RJMP
LDI
OUT
LDI
OUT
RET
R20, HIGH(-1332)
TCNT1H, R20
R20, LOW(-1332)
TCNT1L, R20
R20, (1<<TOV1)
TIFR, R20
R20, 0x00
TCCR1A, R20
R20, 0x01
TCCR1B, R20
R20,TIFR
R20, TOV1
DELAY_L1
R20, 0
TCCR1B, R20
R20, (1<<TOV1)
TIFR, R20
28.
(a) Timer0 is 8-bit whereas Timer1 is 16-bit.
(b) Timer0 has one control register but Timer1 has two control registers (TCCR1A and
TCC1B)
(c) Timer0 can work in four modes while Timer1 has 16 different modes.
29.
(a)
(b)
(c)
(d)
(e)
(f)
– 12 = 0xF4 = 244
– 22 = 0xEA = 234
– 34 = 0xDE = 222
– 92 = 0xA4 = 164
– 120 = 0x88 = 136
– 104 = 0x98 = 152
SECTION 9.2: COUNTER PROGRAMMING
30. CS02–CS00, 110 or 111
31. Yes
32. T0 which is PORTB.0 in ATmega32
33. T1 which is PORTB.1 in ATmega32
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
59
34.
.INCLUDE "M32DEF.INC"
LDI
R20, HIGH(RAMEND)
OUT
SPH, R20
LDI
R20, LOW(RAMEND)
OUT
SPL, R20
L1:
35.
CBI
SBI
DDRB, 1
PORTB, 1
LDI
OUT
OUT
R20, 0xFF
DDRC, R20
DDRD, R20
LDI
OUT
LDI
OUT
R20, HIGH(20000)
TCNT1H, R20
R20, LOW(20000)
TCNT1L, R20
LDI
OUT
LDI
OUT
IN
OUT
IN
OUT
RJMP
R20, 0x00
TCCR1A, R20
R20, 0x07
TCCR1B, R20
R20, TCNT1L
PORTD, R20
R20, TCNT1H
PORTC, R20
L1
.INCLUDE "M32DEF.INC"
LDI
R20, HIGH(RAMEND)
OUT
SPH, R20
LDI
R20, LOW(RAMEND)
OUT
SPL, R20
L1:
CBI
SBI
LDI
OUT
DDRB, 0
PORTB, 0
R20, 0xFF
DDRC, R20
LDI
OUT
LDI
OUT
IN
OUT
RJMP
R20, 20
TCNT0, R20
R20, 0x07
TCCR0, R20
R20, TCNT0
PORTC, R20
L1
SECTION 9.3: PROGRAMMING TIMERS IN C
36. 1 / 1 kHz = 1 ms. Now 1 ms / 2 = 500 µs.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
60
Scaler
None
8
64
256
1024
Timer Clock
1 MHz
1 MHz/8 = 125 kHz
1 MHz / 64 = 15.625 kHz
1 MHz / 256 = 3.90 kHz
1 MHz / 1024 = 976.5 Hz
Timer Period
1 / 1 MHz = 1 µs
1 / 125 kHz = 8 µs
1 / 15.625 kHz = 64 µs
1 / 3.9 kHz = 256 µs
1 / 976.5 Hz = 1024 µs
Timer value
500 µs / 1 µs = 500
500 µs / 8 µs = 62.5
500 µs / 64 µs = 7.8125
500 µs / 256 µs = 15.62
500 µs / 1024 µs = 3.9
#include "avr/io.h"
void delay_500us ( );
int main ()
{
DDRA = DDRA | 1;
while(1)
{
PORTA = PORTA ^ (1 << PA0);
delay_500us ();
}
}
return 0;
void delay_500us ( )
{
TCNT0 = -62;
TCCR0 = 0x02;
TIFR = (1<<TOV0);
while ((TIFR & (1<<TOV0)) == 0);
}
TCCR0 = 0x00;
TIFR = (1<<TOV0);
37. 1 / 1 kHz = 1 ms. Now 1 ms / 2 = 500 µs.
Scaler
None
8
64
256
1024
Timer Clock
8 MHz
8 MHz/8 = 1 MHz
8 MHz / 64 = 125 kHz
8 MHz / 256 = 31.25 kHz
8 MHz / 1024 = 7812.5 Hz
Timer Period
1 / 8 MHz = 0.125 µs
1 / 1 MHz = 1 µs
1 / 125 kHz = 8 µs
1 / 31.25 kHz = 32 µs
1 / 7812.5 Hz = 128 µs
Timer value
500 µs / 0.125 µs = 4000
500 µs / 1 µs = 500
500 µs / 8 µs = 62.5
500 µs / 32 µs = 15.62
500 µs / 128 µs = 3.9
#include "avr/io.h"
void delay_500us ( );
int main ()
{
DDRA = DDRA | 1;
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
61
while(1)
{
PORTA = PORTA ^ (1 << PA0);
delay_500us();
}
}
return 0;
void delay_500us ( )
{
TCNT1H = (-500)>>8;
TCNT1L = (-500)& 0xFF;
TCCR1A = 0;
TCCR1B = 0x2;
TIFR = (1<<TOV1);
while ((TIFR & (1<<TOV1)) == 0);
}
TCCR1B = 0x00;
TIFR = (1<<TOV1);
38. 1 / 3 kHz = 0.333 ms = 333 µs. Now 333 µs / 2 = 166.5 µs.
Scaler
None
8
64
256
1024
Timer Clock
16 MHz
16 MHz/8 = 2 MHz
16 MHz / 64 = 250 kHz
16 MHz / 256 = 62.5 kHz
16 MHz / 1024 = 15625 Hz
Timer Period
1 / 16 MHz = 0.0625 µs
1 / 2 MHz = 0.5 µs
1 / 250 kHz = 4 µs
1 / 62.5 kHz = 16 µs
1 / 15625 Hz = 64 µs
Timer value
166.5 µs / 0.0625 µs = 2664
166.5 µs / 0.5 µs = 333
166.5 µs / 4 µs = 41.625
166.5 µs / 16 µs = 10.4062
166.5 µs / 64 µs = 2.6015
#include "avr/io.h"
void delay_166us ( );
int main ()
{
DDRA = DDRA | 1;
while(1)
{
PORTA = PORTA ^ (1 << PA0);
delay_166us();
}
}
return 0;
void delay_166us ( )
{
TCNT0 = -41;
TCCR0 = 0x03;
TIFR = (1<<TOV0);
while ((TIFR & (1<<TOV0)) == 0);
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
62
}
TCCR0 = 0x00;
TIFR = (1<<TOV0);
39. 1 / 3 kHz = 0.333 ms = 333 µs. Now 333 µs / 2 = 166.5 µs.
Scaler
None
8
64
256
1024
Timer Clock
10 MHz
10 MHz/8 = 1.25 MHz
10 MHz / 64 = 156.25 kHz
10 MHz / 256 = 39.0625 kHz
10 MHz / 1024 = 9.765 Hz
Timer Period
1 / 10 MHz = 0.1 µs
1 / 1.25 MHz = 0.8 µs
1 / 156.25 kHz = 6.4 µs
1 / 39.0625 kHz = 25.6 µs
1 / 9.765 Hz = 102.4 µs
Timer value
166.5 µs / 0.1 µs = 1665
166.5 µs / 0.8 µs = 208.125
166.5 µs / 6.4 µs = 26.01562
166.5 µs / 25.6 µs = 6.5039
166.5 µs / 102.4 µs = 1.6259
#include "avr/io.h"
void delay_166us ( );
int main ()
{
DDRA = DDRA | 1;
while(1)
{
PORTA = PORTA ^ (1 << PA0);
delay_166us();
}
}
return 0;
void delay_166us ( )
{
TCNT1H = (-1665)>>8;
TCNT1L = (-1665)& 0xFF;
TCCR1A = 0;
TCCR1B = 0x1;
TIFR = (1<<TOV1);
while ((TIFR & (1<<TOV1)) == 0);
}
TCCR1B = 0x00;
TIFR = (1<<TOV1);
40.
#include "avr/io.h"
int main ()
{
DDRC = DDRD = 0xFF;
TCNT1 = 20000;
TCCR1A = 0;
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
63
TCCR1B = 0x7;
while(1)
{
PORTC = TCNT1L;
PORTD = TCNT1H;
}
}
return 0;
41.
#include "avr/io.h"
int main ()
{
DDRD = 0xFF;
TCNT0 = 20;
TCCR0 = 0x7;
while(1)
{
PORTD = TCNT0;
}
}
return 0;
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
64
Chapter 10: INTERRUPT PROGRAMMING IN ASSEMBLY AND C
SECTION 10.1: AVR INTERRUPTS
1. interrupt
2. hardware Reset, timer overflow, timer compare match, hardware external interrupt, USART
transmit and receive interrupts, etc
3. $00 to $28
4. True
5. $16
6. $12
7. Yes
8. Yes
9. Status register
10. Because locations $02 to $28 are assigned to interrupt vector.
11. 0, all interrupts are disabled.
12.
LDI
OUT
SEI
R16, (1<<OCIE0)
TIMSK, R16
LDI
OUT
SEI
R16, (1<<TOIE1)
TIMSK, R16
13.
14. TIMSK
15. True
16. CLI
17.
IN
ANDI
OUT
R16, GICR
R16, ~(1<<INT0)
GICR, R16
18. False
19. 4 bytes
SECTION 10.2: PROGRAMMING TIMER INTERRUPTS
20. True
21. $0A and $0B
22.
LDI
OUT
SEI
R16, (1<<TOIE2)
TIMSK, R16
LDI
OUT
SEI
R16, (1<<TOIE0)
TIMSK, R16
23. 0
24. The content of TCNT0 increases, at first becoming $E1, then $E2, and so on until the timer
reaches $FF and rolls over to zero and the TOV0 flag is set. When TOV0 is set the CPU
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
65
finishes executing the current instruction, pushes the PC register onto the stack, clears the I
and the TOV0 flags, and loads PC with $16, since the address of Timer0 overflow interrupt
vector is $16. The ISR ends with the RETI instruction causing the CPU to pop the return
address from the top of stack.
25. False. The CPU automatically clears the TOV0 flag.
26. The content of TCNT1 increases, at first becoming $100, then $101, and so on until the timer
reaches $1F5 and rolls over to zero and the OCF1A flag is set. When OCF1A is set the CPU
finishes executing the current instruction, pushes the PC register onto the stack, clears the I
and the OCF1A flags, and loads PC with $0E, since the address of Timer1 compare match
interrupt vector is $0E. The ISR ends with the RETI instruction causing the CPU to pop the
return address from the top of stack.
27. The content of TCNT1 increases, at first becoming $FFE9, then $FFEA, and so on until the
timer reaches $FFFF and rolls over to zero and the TOV1 flag is set. When TOV1 is set the
CPU finishes executing the current instruction, pushes the PC register onto the stack, clears
the I and the TOV1 flags, and loads PC with $12, since the address of Timer1 compare match
interrupt vector is $12. The ISR ends with the RETI instruction causing the CPU to pop the
return address from the top of stack.
28. To generate a wave with frequency of 1 Hz we need a delay of 0.5 sec.
Scaler Timer Clock
Timer Period
Timer value
None 8 MHz
1 / 8 MHz = 0.125 µs
500 ms / 0.125 µs = 4,000,000
8
8 MHz/8 = 1 MHz
1 / 1 MHz = 1 µs
500 ms / 1 µs = 500,000
64
8 MHz / 64 = 125 kHz
1 / 125 kHz = 8 µs
500 ms / 8 µs = 62,500
256
8 MHz / 256 = 31.25 kHz 1 / 31.25 kHz = 32 µs 500 ms / 32 µs = 15,620
1024
8 MHz / 1024 = 7812.5 Hz 1 / 7812.5 Hz = 128 µs 500 ms / 128 µs = 3900
.INCLUDE "M32DEF.INC"
.ORG 0
RJMP MAIN
.ORG 0x12
RJMP T1_OVER_ISR
MAIN:
LDI
OUT
LDI
OUT
R16,HIGH(RAMEND)
SPH,R16
R16,LOW(RAMEND)
SPL,R16
LDI
OUT
LDI
OUT
R16,HIGH(-62500)
TCNT1H,R16
R16,LOW(-62500)
TCNT1L,R16
LDI
OUT
LDI
OUT
R16,0x00
TCCR1A,R16
R16,0x02
TCCR1B,R16
LDI
OUT
SEI
R16, 1<<TOIE1
TIMSK, R16
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
66
SBI
DDRB, 7
LDI
OUT
R16, 0
DDRC, R16
LDI
OUT
OUT
R16, 0xFF
DDRD, R16
PORTC, R16
L1:
IN
R16, PINC
OUT PORTD,R16
RJMP L1
T1_OVER_ISR:
LDI R16,HIGH(-62500)
OUT TCNT1H,R16
LDI R16,LOW(-62500)
OUT TCNT1L,R16
IN
LDI
EOR
OUT
RETI
R20, PORTB
R21, (1<<PB7)
R20, R21
PORTB, R20
29. 1 / 3 kHz = 333 µs. Now 333 µs / 2 = 166 µs.
Scaler Timer Clock
Timer Period
1 / 1 MHz = 1 µs
None 1 MHz
8
1 MHz/8 = 125 kHz
1 / 125 kHz = 8 µs
64
1 MHz / 64 = 15.625 kHz 1 / 15.625 kHz = 64 µs
256
1 MHz / 256 = 3.90 kHz 1 / 3.9 kHz = 256 µs
1024
1 MHz / 1024 = 976.5 Hz 1 / 976.5 Hz = 1024 µs
Timer value
166 µs / 1 µs = 166
166 µs / 8 µs = 20.75
166 µs / 64 µs = 2.593
166 µs / 256 µs = 0.648
166 µs / 1024 µs = 0.1621
.INCLUDE "M32DEF.INC"
.ORG
.ORG
0
RJMP
0x14
RJMP
MAIN: LDI
OUT
LDI
OUT
MAIN
T0_CM_ISR
R16,HIGH(RAMEND)
SPH,R16
R16,LOW(RAMEND)
SPL,R16
LDI
OUT
R16,166
OCR0,R16
LDI
OUT
R16,0x09
TCCR0,R16
LDI
R16, 1<<OCIE0
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
67
L1:
OUT
SEI
TIMSK, R16
SBI
DDRB, 7
LDI
OUT
R16, 0
DDRC, R16
LDI
OUT
OUT
R16, 0xFF
DDRD, R16
PORTC, R16
IN
OUT
RJMP
R16, PINC
PORTD,R16
L1
T0_CM_ISR:
IN
LDI
EOR
OUT
RETI
R20, PORTB
R21, (1<<PB7)
R20, R21
PORTB, R20
SECTION 10.3: PROGRAMMING EXTERNAL HARDWARE INTERRUPTS
30. True
31. $02, $04, and $06 respectively – PD2, PD3, and PB2 respectively.
32. GICR
LDI
OUT
R16, 1<<INT0
GICR, R16
33. GICR
LDI
OUT
R16, 1<<INT1
GICR, R16
LDI
OUT
R16, (1<<INT0)|(1<<INT1)|(1<<INT2)
GICR, R16
34.
35. When the input signal goes from high to low the processor finishes executing the current
instruction and jumps to vector address to execute the ISR.
36. False
37. GIFR
38. GIFR
39. The edge interrupt is latched by the AVR and is held by the INTF0 bit of the GIFR register.
This means that when an external interrupt is in an edge-triggered mode, upon triggering an
interrupt request, the INTF0 flag will be cleared automatically.
40. Clearing the I-bit makes all the interrupts disabled. Therefore, if the I flag is cleared,
interrupts will not be triggered when the interrupt pins are activated.
41. False
42. In falling edge-triggered interrupt, each high-to-low pulse will cause the CPU to execute the
ISR. In the level-triggered interrupt a low level pulse will interrupt the CPU causing it to
execute the ISR. We must remove the low-level pulse from the interrupt before the execution
of the RETI instruction at the end of ISR; otherwise the CPU will be interrupted again.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
68
43.
LDI
OUT
R16, $02
MCUCR, R16
44. True
45.
.INCLUDE "M32DEF.INC"
.ORG
.ORG
0
RJMP
0x02
RJMP
MAIN: LDI
OUT
LDI
OUT
L1:
MAIN
INT0_ISR
R16,HIGH(RAMEND)
SPH,R16
R16,LOW(RAMEND)
SPL,R16
LDI
OUT
LDI
OUT
CBI
SBI
R16, 0xFF
DDRC, R16
R16, 0
PORTC, R16
DDRD, 2
PORTD, 2
LDI
OUT
R16, 0x02
MCUCR, R16
LDI
OUT
SEI
RJMP
R16, 1<<INT0
GICR, R16
INT0_ISR:
IN
INC
OUT
RETI
L1
R20, PORTC
R20
PORTC, R20
46.
.INCLUDE "M32DEF.INC"
.ORG
.ORG
.ORG
0
RJMP
0x02
RJMP
0x04
RJMP
MAIN: LDI
OUT
LDI
OUT
LDI
OUT
LDI
OUT
MAIN
INT0_ISR
INT1_ISR
R16,HIGH(RAMEND)
SPH,R16
R16,LOW(RAMEND)
SPL,R16
R16, 0xFF
DDRC, R16
R16, 0
PORTC, R16
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
69
L1:
CBI
SBI
CBI
SBI
SBI
LDI
OUT
DDRD, 2
PORTD, 2
DDRD, 3
PORTD, 3
DDRD, 7
R16, 0x0A
MCUCR, R16
LDI
OUT
SEI
RJMP
R16, (1<<INT0)|(1<<INT1)
GICR, R16
L1
INT0_ISR:
IN
INC
OUT
RCALL
RETI
R20, PORTC
R20
PORTC, R20
SET_PD7
INT1_ISR:
IN
DEC
OUT
RCALL
RETI
R20, PORTC
R20
PORTC, R20
SET_PD7
SET_PD7:
CPI
R20, 2
BRCS SET_PD7_L1
SBI
PORTD,7
RJMP SET_PD7_L2
SET_PD7_L1:
CBI
PORTD,7
SET_PD7_L2:
RET
SECTION 10.4: INTERRUPT PRIORITY IN THE AVR
47. If two interrupts are activated at the same time, the interrupt with the higher priority is served
first. The address of external interrupt 1 is $4 while the address of external interrupt 2 is $6;
thus, external interrupt 1 has a higher priority, and if both of these interrupts are activated at
the same time, external interrupt 1 is served first.
48. The address of Timer1 overflow interrupt is $12 while the address of Timer0 overflow
interrupt is $16; thus, Timer1 overflow interrupt has a higher priority, and if both of these
interrupts are activated at the same time, Timer1 overflow interrupt is served first.
49. When the AVR begins to execute an ISR, it disables the I bit of the SREG register, causing
all the interrupts to be disabled, and no other interrupt occurs while serving the interrupt.
50. True; if we want an interrupt to be served inside an interrupt, we should enable the interrupt
manually.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
70
CHAPTER 11: AVR SERIAL PORT PROGRAMMING IN
ASSEMBLY AND C
SECTION 11.1: BASICS OF SERIAL COMMUNICATION
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Parallel
False
1010110100 ---> this start bit goes first
Mark
False. It can be 1 or 2 but we always need stop bit.
7 bit data + 1 stop bit + 1 start bit = 9 bits
2/9 x 100 = 22%
False
It makes the RS232 standard compatible with TTL logic level.
False
9 pins, since the rest are not involved in data transfer.
False
3: TxD RxD Gnd
DTE -to- DTE
DCD, RxD, TxD, DTR, Gnd, DSR, RTS, CTS, RI
4,000,000 bits (200 x 80 x 25 x 10)
416.6 seconds
SECTION 11.2: ATMEGA32 CONNECTION TO RS232
17.
18.
19.
20.
21.
22.
23.
24.
25.
16
VCC = 16, GND = 15
20
VCC = 7, GND =6
No
The MAX233 does not require an external capacitor, but it is more expensive.
2
2
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
71
26.
27.
28.
It does not need the four capacitors that the MAX232 must have.
Pin 15 – TXD, pin 14 – RXD.
SECTION 11.3: AVR SERIAL PORT PROGRAMMING IN ASSEMBLY
29.
30.
31.
32.
33.
34.
35.
36.
(a), (c), (e), (f)
UDR (USART Data Register), UCSRA,UCSRB, UCSRC (USART Control Status
Register), and UBRR (USART Baud Rate Register)
U2X (Bit1): Double the USART Transmission Speed
When you write data to UDR, it will be transferred to the Transmit Data Buffer Register
(TXB), and when you read data from UDR, it will return the contents of the Receive Data
Buffer Register (RXB).
8
X = (10 MHz/(16(Desired Baud Rate))) – 1
Î X = (625 kHz/(Desired Baud Rate)) – 1.
(a) (625 kHz/9600) – 1= 64 = 0x40
(b) (625 kHz/4800) – 1= 129 = 0x81
(c) (625 kHz/1200) – 1= 519 = 0x207
Baud Rate = Fosc/ (16(X + 1)) = 10MHz / (16(15+1)) = 39062
.INCLUDE "M32DEF.INC"
LDI
R16,(1<<TXEN)
;enable transmitter
OUT
UCSRB, R16 ;
LDI
R16,(1<<UCSZ1)|(1<<UCSZ0)|(1<<URSEL) ;8-bit data
OUT
UCSRC, R16
;no parity, 1 stop bit
LDI
R16,64
;9600 baud rate
OUT
UBRRL,R16
;for XTAL = 10 MHz
AGAIN:
SBIS UCSRA,UDRE
;is UDR empty
RJMP AGAIN
;wait more
LDI
R16,'z'
;send ‘G’
OUT
UDR,R16
;to UDR
RJMP AGAIN
;do it again
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
72
37.
This bit is set if parity checking was enabled (UPM1 = 1) and the next character in the
receive buffer had a parity error when received.
38.
This flag bit is set when there are new data in the receive buffer that are not read yet. It is
cleared when the receive buffer is empty.
39.
This flag is set when the transmit data buffer is empty and you can write new data to it. If
this bit is cleared you should not write to UDR because it overrides your last data.
40.
UCSRA.
41.
X = (16 MHz/16(Desired Baud Rate)) – 1
Î X = (1 MHz/(Desired Baud Rate)) – 1.
(a) (1 MHz/9600) – 1= 103
(b) (1 MHz/19200) – 1= 51
(c) (1 MHz/38400) – 1= 25
(d) (1 MHz/57600) – 1= 16
42.
X = (16 MHz/8(Desired Baud Rate)) – 1
Î X = (2 MHz/(Desired Baud Rate)) – 1.
(a) (2 MHz/9600) – 1= 207
(b) (2 MHz/19200) – 1= 103
(c) (2 MHz/38400) – 1= 51
(d) (2 MHz/57600) – 1= 34
43.
X = (11.0592 MHz/16(Desired Baud Rate)) – 1
Î X = (691200Hz /(Desired Baud Rate)) – 1.
(a) (691200Hz/9600) – 1= 71
(b) (691200Hz /19200) – 1= 35
(c) (691200Hz /38400) – 1= 17
(d) (691200Hz /57600) – 1= 11
44.
X = (11.0592MHz/8(Desired Baud Rate)) – 1
Î X = (1382400Hz/(Desired Baud Rate)) – 1.
(a) (1382400Hz /9600) – 1= 143
(b) (1382400Hz /19200) – 1= 71
(c) (1382400Hz /38400) – 1= 35
(d) (1382400Hz /57600) – 1= 23
45.
Error = (Calculated value for the UBRR – Integer part) / Integer part
(a) (103.166 -103) /103 = 0.16%
(b) (51.08 - 51) / 51 = 0.16%
(c) (25.04 - 25) / 25 = 0.16%
(d) (16.36 - 16) / 16 = 2.2%
46.
Error = (Calculated value for the UBRR – Integer part) / Integer part
(a) (207.33 - 207) /207 = 0.16%
(b) (103.166 -103) /103 = 0.16%
(c) (51.08 - 51) / 51 = 0.16%
(d) (33.72 - 33) /33 = 2.1%
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
73
47.
Error = (Calculated value for the UBRR – Integer part) / Integer part
(a) (71-71) / 71 = 0%
(b) (35-35) / 35 = 0%
(c) (17- 17) / 17 = 0%
(d) (11 - 11) /11 = 0%
48.
Error = (Calculated value for the UBRR – Integer part) / Integer part
(a) (143-143) / 143 = 0%
(b) (71-71) / 71 = 0%
(c) (35-35) / 35 = 0%
(d) (23- 23) / 23 = 0%
SECTION 11.4: AVR SERIAL PORT PROGRAMMING IN C
49.
#include <avr/io.h>
//standard AVR header
int main (void)
{
//initialize USART transmitter for 8 bit data no parity
//and one stop bit
UCSRB = (1<<TXEN) ;
UCSRC = (1<< UCSZ1)|(1<<UCSZ0)|(1<<URSEL);
UBRRL = 0x33 ;
while (! (UCSRA & (1<<UDRE))); //wait until UDR is empty
UDR = 'Z' ;
}
return 0 ;
50.
#include <avr/io.h>
//standard AVR header
void transmit ( unsigned char data )
{
while (! (UCSRA & (1<<UDRE))); //wait until UDR is empty
UDR = data;
}
void serial_putstr( unsigned char str [] )
{
unsigned char i = 0;
while(str[i] != 0)
transmit(str[i++]);
}
int main (void)
{
//initialize USART transmitter for 8 bit data no parity
//and one stop bit
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
74
UCSRB = (1<<TXEN) ;
UCSRC = (1<< UCSZ1)|(1<<UCSZ0)|(1<<URSEL);
UBRRL = 0x33 ;
}
serial_putstr("The Earth is but One Country.");
return 0 ;
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
75
CHAPTER 12: LCD AND KEYBOARD INTERFACING
SECTION 12.1: LCD INTERFACING
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
14
They are the control lines for the LCD. E is for latching information into the LCD, R/W
is for reading from or writing information into the LCD , and RS is for making a
distinction between the data and command.
Vee controls the contrast of the screen while Vcc provides power to the LCD.
command, 01h
0Eh
RS = 0, RW = 0, E = H-to-L pulse
RS = 1, RW = 0, E = H-to-L pulse
(a) H-toL
True
Sending information to the LCD in the 8-bit mode needs less coding and save the
programmer times but it needs 8 pins for data plus the pins needed for control. The 4-bit
mode, uses only 4 pins for data and save 4 pins. However, the subroutine for 4-bit data is
much harder to write and takes more code.
80h is the starting location ,and 16 locations to the right is 8Fh.
C4h. This is 4 locations from C0h since C0 is the first location of line 2.
C0h is the starting location, and 20 locations to the right is 13h which result in C0h + 13h
= D3h.
C2h. This is 2 locations from C0h since C0 is the first location of line 2.
If 80h is the address of the first location, then adding 39 (27h) we get 80h + 27h = A7h.
If C0h is the address of the first location, then adding 39 (27h) we get C0h + 27h = E7h.
89h since 80h + 9 = 89h. The 10th is address 9 since it starts at 0.
C0h + 13h = D3h. Notice that the 20th starts at 0 and goes to 13h.
SECTION 12.2: KEYBOARD INTERFACING
19.
20.
21.
22.
23.
24.
All 1’s
(a)
(b)
(a) F (b) 0
1) Ground all rows. 2) Read the columns. 3) If all columns are high go to step 1.
1) Ground one row at a time. 2) Read the columns. 3) If all columns are high ground the
next row. 4) When a low column is found, we get the key code from the look-up table.
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
76
CHAPTER 13: ADC, DAC, AND SENSOR INTERFACING
SECTION 13.1: ADC CHARACTERISTICS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
True
True
True
False
True
True
False
True
False
False
(d)
(d)
(a) (5V) / (28) = 19.53 mV
(b) (5V) / (210) = 4.88 mV
(c) (5V) / (212) = 1.22 mV
(d) (5V) / (216) = 76.29 µV
The step size is 1.28 / (28) = 5 mV
(a) since the step size is 5 mV and all inputs are high, we get 255 x 5 mV = 1.275 V.
(b) 10011001 = 153 and 153 x 5 mV = 0.756 V.
(c) 1101100= 108 and 108 x 5 mV = 0.540 V.
1.28 V since 256 x 5 mV = 1.28V
(a) since the step size is 10 mV and all inputs are high, we get 255 x 10 mV = 2.56 V.
(b) 10011001 = 153 and 153 x 10 mV = 1.53 V.
(c) 1101100= 108 and 108 x 10 mV = 1.08 V.
SECTION 13.2: ADC PROGRAMMING IN THE ATMEGA32
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
True
False. It is 10-bit
True
True
True
False
False
True
False
True
It is kept by the ADCH:ADCL registers. At the end of conversion, the ADIF flag in
ADCSRA register is set.
The old data gets lost.
(a) 1.024V / 1024 = 1 mV
(b) 2.048 / 1024 = 2 mV
(c) 2.56 / 1024 = 2.5 mV
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
77
30.
31.
32.
33.
34.
35.
36.
2 mV x 1024 = 2048mV = 2.048V
3 mV x 1024 = 3.072V
1 mV x 1023 = 1.023V
Step Size = 1.024 /1024 = 1 mV
(a) 255 x 1 mV = 0.255V
(b) 152 x 1 mV = 0.152V
(c) 208 x 1 mV = 0.208V
4 mV x 1024 = 4096 mV = 4.096 V
Step Size = 2.56/1024 = 2.5 mV
(a) 1023 x 2.5 mV = 2.5575V
(b) 513 x 2.5mV = 1.2825V
(c) 816 x 2.5 mV = 2.04V
The crystal frequency is 8MHz
(a) Fosc/2 = 8 MHz / 2 = 4 MHz (greater than 200 kHz and not valid)
(b) Fosc/4 = 8 MHz / 4 = 2 MHz (greater than 200 kHz and not valid)
(c) Fosc/8 = 8 MHz / 8 = 1 MHz (greater than 200 kHz and not valid)
(d) Fosc/2 = 8 MHz / 16 = 500 KHz (greater than 200 kHz and not valid)
(e) Fosc/2 = 8 MHz / 32 = 250 KHz (greater than 200 kHz and not valid)
Note: It is not needed to calculate first conversion time because none of the above
frequencies are valid.
37.
The crystal frequency is 4MHz
(a) Fosc/8 = 4 MHz / 8 = 500 KHz (greater than 200 kHz and not valid)
(b) Fosc/16 = 4 MHz / 16 = 250 KHz (greater than 200 kHz and not valid)
(c) Fosc/32 = 4 MHz / 32 = 125.5 KHz => T = 1/ 125.5 KHz = 8 microseconds
first conversion takes 25 ADC clock cycles = 25 * 8 microsecond = 200 microseconds
(d) Fosc/64 = 4 MHz / 64 = 62.75 KHz => T = 1/ 62.75 KHz = 16 microseconds
first conversion takes 25 ADC clock cycles = 25 * 16 microsecond = 400 microseconds
38.
39.
40.
41.
42.
43.
By writing a one to the ADSC bit of ADCSRA.
By polling the ADIF bit in the ADCSRA register..
ADPS2:0 (Bit2:0) of ADCSRA
MUX4…MUX0 bits of ADMUX register.
ADIF ( bit 4 ) of ADCSRA register.
off.
SECTION 13.3: SENSOR INTERFACING AND SIGNAL CONDITIONING
44.
45.
46.
The output corresponds with the input linearly (in a straight line).
10 mV
Adjusting the output of a given sensor (device) to meet the input needs of the ADC chip
SECTION 13.4: DAC INTERFACING
47.
48.
49.
50.
True.
(a) 256
(b) 1024
(c) 4096
2 mA x (255/256) = 1.99 mA
(a) 1.195 mA since 10011001B = 153 and (153 x 2 mA)/256 = 1.195 mA
(b) 1.594 mA since 11001100B = 204 and (204 x 2 mA)/256= 1.594 mA
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
78
51.
52.
(c) 1.859 mA since 11101110B = 238 and (238 x 2 mA)/256 = 1.859 mA
(d) 0.2656 mA
(e) 0.0703125 mA
(f) 1.063 mA
More
All high
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
79
Chapter 14: RELAY, OPTOISOLATOR, AND STEPPER MOTOR
INTERFACING WITH AVR
SECTION 14.1: RELAYS AND OPTOISOLATORS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
False
True
There is no coil, spring or mechanical contact
False
5 / 1200 = 4.167 mA
Motor control and telecommunications
size and speed
EM relay
True
False
SECTION 14.2: STEPPER MOTOR INTERFACING
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
360 / 90 = 4 degrees
48
1001, 1100, 0110
0110, 0011, 1001
0011, 0110, 1100
1100, 1001, 0011
The ULN2003 provides addition current for driving the motor, No
b
Slows the motor
Decrease the time delay between steps
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
80
Chapter 15: INPUT CAPTURE AND WAVE GENERATION IN AVR
SECTION 15.1: WAVE GENERATION USING 8-BIT TIMERS
1.
2.
3.
4.
5.
False
False
True
PD7
TTimer Clock = 1 / 8 MHz = 0.125 µs
TWave = 1/ 80 kHz = 12.5 µs Î Ttoggle = 12.5 / 2 = 6.25 µs
6.25 / 0.125 = 50 Î OCR0 = 49
.INCLUDE "M32DEF.INC"
SBI
DDRB,3
LDI
R20, 49
OUT
OCR0, R20
LDI
R20, 0x19
OUT
TCCR0, R20
L1:
RJMP L1
6.
//OCR0 = 49
//N = 1, CTC mode, toggle
TTimer Clock = 1 / 1 MHz = 1 µs
TWave = 1/ 5 kHz = 0.2 ms Î Ttoggle = 0.2 / 2 = 0.1 ms = 100 µs
100 / 1 = 100 Î OCR0 = 99
.INCLUDE "M32DEF.INC"
SBI
DDRB,3
LDI
R20, 99
OUT
OCR0, R20
LDI
R20, 0x19
OUT
TCCR0, R20
L1:
RJMP L1
7.
//OC0 as output
//OC0 as output
//OCR0 = 99
//N = 1, CTC mode, toggle
TTimer Clock = 1 / 8 MHz = 0.125 µs
TWave = 1/ 625 Hz = 1.6 ms Î Ttoggle = 1.6 / 2 = 0.8 ms = 800 µs
800 / 0.125 = 6400 Î OCR0 = 99
N
1
8
64
256
1024
Timer clocks
6400 / 1 = 6400
6400 / 8 = 800
6400 / 64 = 100
6400 / 256 = 25
6400 / 1024 = 6.25
OCR0
Too big
Too big
99
24
5.25
.INCLUDE "M32DEF.INC"
L1:
SBI
LDI
OUT
LDI
OUT
RJMP
DDRB,3
R20, 99
OCR0, R20
R20, 0x1B
TCCR0, R20
L1
//PB3(OC0) as output
//OCR0 = 99
//CTC mode, N = 64, toggle
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
81
8.
TTimer Clock = 1 / 16 MHz = 0.0625 µs
TWave = 1/ 3125 Hz = 320 µs Î Ttoggle = 320 / 2 = 160 µs
160 / 0.0625 = 2560
N
1
8
64
256
1024
Timer clocks
2560 / 1 = 2560
2560 / 8 = 320
2560 / 64 = 40
2560 / 256 = 10
2560 / 1024 = 2.5
OCR0
Too big
Too big
39
9
1.5
.INCLUDE "M32DEF.INC"
L1:
SBI
LDI
OUT
LDI
OUT
RJMP
DDRB,3
R20, 39
OCR0, R20
R20, 0x1B
TCCR0, R20
L1
//PB3(OC0) as output
//OCR0 = 39
//CTC mode, N = 64, toggle
SECTION 15.2: WAVE GENERATION USING TIMER1
9.
10.
11.
True
4
TTimer Clock = 1 / 8 MHz = 0.125 µs
TWave = 1/ 1 kHz = 1 ms Î Ttoggle = 1 ms / 2 = 0.5 ms = 500 µs
500 / 0.125 = 4000 Î OCR1 = 3999
.INCLUDE "M32DEF.INC"
L1:
12.
SBI
LDI
OUT
LDI
OUT
LDI
OUT
LDI
OUT
RJMP
DDRD, 5
R20, HIGH(3999)
OCR1AH, R20
R20, LOW(3999)
OCR1AL, R20
R20, 0x40
TCCR1A, R20
R20, 0x09
TCCR1B, R20
L1
;OCR1A = 3999
;Toggle Generator A
;CTC, No prescaler
TTimer Clock = 1 / 8 MHz = 0.125 µs
TWave = 1/ 5 kHz = 0.2 ms Î Ttoggle = 0.2 ms / 2 = 0.1 ms = 100 µs
100 / 0.125 = 800 Î OCR1 = 799
.INCLUDE "M32DEF.INC"
SBI
LDI
OUT
LDI
OUT
DDRD, 5
R20, HIGH(799)
OCR1AH, R20
R20, LOW(799)
OCR1AL, R20
;PD5(OC1A) as output
;OCR1A = 799
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
82
L1:
13.
LDI
OUT
LDI
OUT
RJMP
R20, 0x40
TCCR1A, R20
R20, 0x09
TCCR1B, R20
L1
;Toggle Generator A
;CTC, No prescaler, toggle
;stay here forever
TTimer Clock = 1 / 8 MHz = 0.125 µs
TWave = 1/ 50 Hz = 0.02 s Î Ttoggle = 0.02 s / 2 = 0.01 s = 10 ms = 10,000 µs
10,000 / 0.125 = 80,000
N
1
8
64
256
1024
Timer clocks
80,000 / 1 = 80,000
80,000 / 8 = 10,000
80,000 / 64 = 1,250
80,000 / 256 = 312.5
80,000 / 1024 = 78.125
OCR1
Too big
9999
1249
311
77
.INCLUDE "M32DEF.INC"
L1:
14.
SBI
LDI
OUT
LDI
OUT
LDI
OUT
LDI
OUT
RJMP
DDRD, 5
R20, HIGH(1249)
OCR1AH, R20
R20, LOW(1249)
OCR1AL, R20
R20, 0x40
TCCR1A, R20
R20, 0x0B
TCCR1B, R20
L1
;PD5(OC1A) as output
;OCR1A = 1249
;Toggle Generator A
;CTC mode, N = 64
TTimer Clock = 1 / 16 MHz = 0.0625 µs
TWave = 1/ 20 Hz = 0.05 s Î Ttoggle = 0.05 s / 2 = 0.025 s = 25 ms = 25,000 µs
25,000 / 0.0625 = 400,000
N
1
8
64
256
1024
Timer clocks
400,000 / 1 = 400,000
400,000 / 8 = 50,000
400,000 / 64 = 6,250
400,000 / 256 = 1562.5
400,000 / 1024 = 390.625
OCR1
Too big
49999
6249
1561
389
.INCLUDE "M32DEF.INC"
L1:
SBI
LDI
OUT
LDI
OUT
LDI
OUT
LDI
OUT
RJMP
DDRD, 5
;PD5(OC1A) as output
R20, HIGH(6249)
OCR1AH, R20
R20, LOW(6249)
OCR1AL, R20 ;OCR1A = 6249
R20, 0x40
;Toggle Generator A
TCCR1A, R20
R20, 0x0B
;CTC mode, N = 64, toggle
TCCR1B, R20
L1
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
83
SECTION 15.3: INPUT CAPTURE PROGRAMMING
15.
16.
17.
18.
19.
20.
The Input Capture function is widely used for many applications. Among them are (a)
recording the arrival time of an event, (b) pulse width measurement, and (c) period
measurement.
False
False
Timer1
0x01
0x41
SECTION 15.4: C PROGRAMMING
21.
TTimer Clock = 1 / 8 MHz = 0.125 µs
TWave = 1/ 50 kHz = 0.02 ms Î Ttoggle = 0.02 s / 2 = 0.01 ms = 10 µs
10 / 0.125 = 80 Î OCR0 = 79
#include "avr/io.h"
int main ()
{
DDRB = DDRB | (1<<3);
//PB3(OC0) as output
OCR0 = 79;
TCCR0 = 0x19;
//CTC mode, no prescaler, toggle
}
22.
while(1);
//stay here forever
TTimer Clock = 1 / 1 MHz = 1 µs
TWave = 1/ 20 kHz = 0.05 ms Î Ttoggle = 0.05 s / 2 = 0.025 ms = 25 µs
25 / 1 = 25 Î OCR2 = 24
#include "avr/io.h"
int main ()
{
DDRD = DDRD | (1<<7);
OCR2 = 24;
TCCR2 = 0x19;
}
23.
while(1);
//PD7(OC2) as output
//CTC mode, no prescaler, toggle
//stay here forever
TTimer Clock = 1 / 8 MHz = 0.125 µs
TWave = 1/ 100 Hz = 10 ms Î Ttoggle = 10 ms / 2 = 5 ms = 5000 µs
5000 / 0.125 = 40,000 Î 40,000/ 256 = 156.25 Î OCR2 = 155
#include "avr/io.h"
int main ()
{
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
84
DDRD = DDRD | (1<<7); //PD7(OC2) as output
OCR2 = 155;
TCCR2 = 0x1E;
//N = 256
}
24.
while(1);
//stay here forever
TTimer Clock = 1 / 1 MHz = 1 µs
TWave = 1/ 95 Hz = 10.52 ms Î Ttoggle = 10.526 ms / 2 = 5.263 ms = 5263 µs
5263 / 1 = 5263 Î 5263/ 64 = 82.23 Î OCR0 = 81
#include "avr/io.h"
int main ()
{
DDRB = DDRB | (1<<3);
//PB3(OC0) as output
OCR0 = 81;
TCCR0 = 0x1B;
//CTC mode, N = 64, toggle
}
25.
while(1);
//stay here forever
TTimer Clock = 1 / 8 MHz = 0.125 µs Î 0.125 µs * 1024 = 128 µs
TWave = 1/ 50 Hz = 0.02 s Î Ttoggle = 0.02 s / 2 = 0.01 s =10,000 Î 10000 / 128 = 78.125
Î OCR0 = 77
TWave = 1/ 60 Hz = 0.016 s Î Ttoggle = 0.016 s / 2 = 0.008 s = 8,000 Î 8000 / 128 = 62.5
Î OCR0 = 61
#include "avr/io.h"
int main ()
{
PORTB = PORTB | (1<<1); //pull-up register
DDRB = DDRB | (1<<3);
//PB3(OC0) as output
OCR0 = 81;
TCCR0 = 0x1D;
//CTC mode, toggle, N = 1024
}
26.
while(1)
{
if(PINB&(1<<1))
OCR0 = 77;
else
OCR0 = 61;
}
//50Hz
//60Hz
TTimer Clock = 1 / 8 MHz = 0.125 µs
TWave = 1/ 3 kHz = 333 µs Î Ttoggle = 333 µs / 2 = 166.5 s Î 166.5 / 0.125 = 1332 Î
OCR1 = 1331
#include "avr/io.h"
int main ()
{
DDRD = DDRD | (1<<5);
//PD5(OC1A) as output
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
85
OCR1A = 1331;
TCCR1A = 0x40;
TCCR1B = 0x09;
}
27.
//toggle OC1A on compare match
//N = 1, CTC (mode 4)
while(1);
TTimer Clock = 1 / 8 MHz = 0.125 µs
TWave = 1/ 44 kHz = 22.727 µs Î Ttoggle = 22.727 µs / 2 = 11.36 µs Î 11.36 / 0.125 =
90.90 Î OCR1 = 90
#include "avr/io.h"
int main ()
{
DDRD = DDRD | (1<<5);
OCR1A = 90;
TCCR1A = 0x40;
TCCR1B = 0x09;
}
//PD5(OC1A) as output
//toggle OC1A on compare match
//N = 1, CTC (mode 4)
while(1);
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
86
Chapter 16: PWM AND DC MOTOR CONTROL
SECTION 16.1: DC MOTOR INTERFACING AND PWM
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Stepper motor
The higher the load, the higher the current draw
False
no-load
Speed control
Positioning and angle control
True
Pulse width modulation. Higher duty cycle leads to higher speed of the motor
Vary the PWM
An optoisolator protects the microcontroller pin from EMF
SECTION 16.2: PWM MODES IN 8-BIT TIMERS
11.
62.5 k = 16 M / (256 x N) Î N = 16 M / 62.5 k x 256 = 1
60 = [(OCR0 + 1) / 256] x 100 Î OCR0 + 1 = 60 x 256 / 100 = 153.6 Î OCR0 = 153
.INCLUDE "M32DEF.INC"
L1:
12.
SBI
LDI
OUT
LDI
OUT
RJMP
DDRB,3
R20, 153
OCR0, R20
R20, 0x69
TCCR0, R20
L1
;PB3(OC0) as output
;OCR0 = 153
;N = 1, non-inverted fast PWM
;stay here forever
46.875 k = 12 M / (256 x N) Î N = 12 M / 46.875 k x 256 = 1
70 = [(255 – OCR0) / 256] x 100 Î 255 – OCR0 = 70 x 256 / 100 = 179.2 Î OCR0 =
255 – 179 = 76
.INCLUDE "M32DEF.INC"
L1:
13.
SBI
LDI
OUT
LDI
OUT
RJMP
DDRB,3
R20, 76
OCR0, R20
R20, 0x79
TCCR0, R20
L1
//PB3(OC0) as output
//OCR0 = 76
//inverted fast PWM, N = 1
//stay here forever
1953 = 4 M / (256 x N) Î N = 4 M / 256 x 1953 = 8
20 = [(255 – OCR0) / 256] x 100 Î 255 – OCR0 = 20 x 256 / 100 = 51.2 Î OCR0 =
255 – 51.2 = 204
.INCLUDE "M32DEF.INC"
SBI
LDI
OUT
DDRB,3
R20, 204
OCR0, R20
//PB3(OC0) as output
//OCR0 = 204
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
87
L1:
14.
LDI
OUT
RJMP
R20, 0x7A
TCCR0, R20
L1
//inverted fast PWM
//stay here forever
15.25 = 1 M / (256 x N) Î N = 1 M / 15.25 x 256 = 256
10 = [(OCR0 + 1) / 256] x 100 Î OCR0 + 1 = 10 x 256 / 100 = 25.6 Î OCR0 = 25
.INCLUDE "M32DEF.INC"
L1:
15.
SBI
LDI
OUT
LDI
OUT
RJMP
DDRB,3
R20, 25
OCR0, R20
R20, 0x6C
TCCR0, R20
L1
//PB3(OC0) as output
//OCR0 = 25
//non-inverted fast PWM, N = 256
//stay here forever
1960 = 1M /(510xN) Î N = 1M / (1960 x 510) Î N = 1
Duty cycle = 20 = [(255 – OCR0) / 255] x 100 Î255 – OCR0 = 51 Î OCR0 = 204
.INCLUDE "M32DEF.INC"
L1:
16.
SBI
LDI
OUT
LDI
OUT
RJMP
DDRB,3
R20, 204
OCR0, R20
R20, 0x71
TCCR0, R20
L1
//OCR0 = 204
//inverted phase correct, N = 1
//stay here forever
1960 = 1M /(510xN) Î N = 1M / (1960 x 510) Î N = 1
Duty cycle = 95 = [(255 – OCR0) / 255] x 100 Î255 – OCR0 = 242.25 Î OCR0 = 13
.INCLUDE "M32DEF.INC"
SBI
DDRB,3
LDI
R20, 13
OUT
OCR0, R20
LDI
R20, 0x71
OUT
TCCR0, R20
L1:
RJMP L1
17.
//PB3(OC0) as output
//PB3(OC0) as output
//OCR0 = 13
//inverted, N = 1
//stay here forever
61.3 = 8M /(510xN) Î N = 8M / (61.3 x 510) Î N = 256
Duty cycle = 19 = [OCR2 / 255] x 100 ÎOCR2 = 48.45 Î OCR2 = 48
.INCLUDE "M32DEF.INC"
L1:
18.
SBI
LDI
OUT
LDI
OUT
RJMP
DDRD,7
R20, 48
OCR2, R20
R20, 0x66
TCCR2, R20
L1
//PD7(OC2) as output
//OCR2 = 48
//non-inverted phase correct, N = 256
//stay here forever
245 = 1M /(510xN) Î N = 1M / (245 x 510) Î N = 8
Duty cycle = 82 = [(255 – OCR2) / 255] x 100 Î255 – OCR2 = 209 Î OCR0 = 46
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
88
.INCLUDE "M32DEF.INC"
SBI
DDRD,7
LDI
R20, 46
OUT
OCR2, R20
LDI
R20, 0x72
OUT
TCCR2, R20
L1:
RJMP L1
//PD7(OC2) as output
//OCR2 = 46
//inverted phase correct, N = 8
//stay here forever
SECTION 16.3: PWM MODES IN TIMER1
19.
15625 = 8 M / (512 x N) Î N = 8 M / 15625 x 512 = 1
Duty cycle = 40 = 100 x (OCR1x + 1) / 512 Î OCR1x + 1 = 204.8 Î OCR1x = 204
.INCLUDE "M32DEF.INC"
L1:
20.
SBI
LDI
OUT
LDI
OUT
LDI
OUT
LDI
OUT
RJMP
DDRD,5
R20, HIGH(204)
OCR1AH, R20
R20, LOW(204)
OCR1AL, R20
R20, 0x82
TCCR1A, R20
R20, 0x09
TCCR1B, R20
L1
//PD5(OC1A) as output
//OCR1A = 204
//mode 6, non-inverted Fast PWM
//N = 1
//stay here forever
3906 = 4 M / (1024 x N) Î N = 4 M / 3906 x 1024 = 1
45 = 100 x (1023 – OCR1x) / 1024 Î 1023 – OCR1x = 460.8 Î OCR1x = 562
.INCLUDE "M32DEF.INC"
L1:
21.
SBI
LDI
OUT
LDI
OUT
LDI
OUT
LDI
OUT
RJMP
DDRD,5
R20, HIGH(562)
OCR1AH, R20
R20, LOW(562)
OCR1AL, R20
R20, 0xC3
TCCR1A, R20
R20, 0x09
TCCR1B, R20
L1
//PD5(OC1A) as output
//OCR1A = 562
//mode 7, non-inverted Fast PWM
//N = 1
//stay here forever
1953 = 16 M / (1024 x N) Î N = 16 M / 1953 x 1024 = 8
35 = 100 x (1023 – OCR1x) / 1024 Î 1023 – OCR1x = 358.4 Î OCR1x = 665
.INCLUDE "M32DEF.INC"
SBI
LDI
OUT
LDI
OUT
LDI
OUT
DDRD,5
R20, HIGH(665)
OCR1AH, R20
R20, LOW(665)
OCR1AL, R20
R20, 0xC3
TCCR1A, R20
//PD5(OC1A) as output
//OCR1A = 665
//mode 7, inverted Fast PWM
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
89
L1:
22.
LDI
OUT
RJMP
R20, 0x0A
TCCR1B, R20
L1
//N = 8
//stay here forever
1953 = 8 M / (512 x N) Î N = 8 M / 1953 x 512 = 8
50 = 100 x (OCR1x + 1) / 512 Î OCR1x + 1 = 256 Î OCR1x = 255
.INCLUDE "M32DEF.INC"
L1:
23.
SBI
LDI
OUT
LDI
OUT
LDI
OUT
LDI
OUT
RJMP
DDRD,5
R20, HIGH(255)
OCR1AH, R20
R20, LOW(255)
OCR1AL, R20
R20, 0x82
TCCR1A, R20
R20, 0x0A
TCCR1B, R20
L1
//PD5(OC1A) as output
//OCR1A = 255
//mode 6, non-inverted Fast PWM
//N = 8
//stay here forever
976 = 4 M / (510 x N) Î N = 4 M / 976 x 510 = 8
35 = 100 x (255 – OCR1x) / 255 Î 255 – OCR1x = 89.25 Î OCR1x = 165.75 ≈ 166
.INCLUDE "M32DEF.INC"
PWM
L1:
24.
SBI
LDI
OUT
LDI
OUT
LDI
OUT
DDRD,5
R20, HIGH(166)
OCR1AH, R20
R20, LOW(166)
OCR1AL, R20
R20, 0xC1
TCCR1A, R20
//PD5(OC1A) as output
//mode 1, inverted phase correct
LDI
OUT
RJMP
R20, 0x02
TCCR1B, R20
L1
//N = 8
//stay here forever
//OCR1A = 166
30.5 = 8 M / (1022 x N) Î N = 8 M / 1022 x 30.5 = 256
25 = 100 x OCR1x / 511 Î OCR1x = 127.75 ≈ 128
.INCLUDE "M32DEF.INC"
SBI
LDI
OUT
LDI
OUT
LDI
OUT
correct PWM
LDI
OUT
L1:
RJMP
DDRD,5
R20, HIGH(128)
OCR1AH, R20
R20, LOW(128)
OCR1AL, R20
R20, 0x82
TCCR1A, R20
//PD5(OC1A) as output
//mode 2, non-inverted phase
R20, 0x04
TCCR1B, R20
L1
//N = 256
//stay here
//OCR1A = 128
Instructor’s Manual for “The AVR Microcontroller and Embedded Systems”
90
25.
245 = 8 M / (510 x N) Î N = 8 M / 245 x 510 = 64
19 = 100 x OCR1x / 255 Î OCR1x = 48.45 Î OCR1x = 48
.INCLUDE "M32DEF.INC"
SBI
LDI
OUT
LDI
OUT
26.
DDRD,5
R20, HIGH(48)
OCR1AH, R20
R20, LOW(48)
OCR1AL, R20
//OCR1A = 48
LDI
OUT
correct PWM
LDI
OUT
R20, 0x81
TCCR1A, R20
//mode 1, non-inverted phase
R20, 0x03
TCCR1B, R20
//N = 64
L1:
L1
//stay here forever
RJMP
//PD5(OC1A) as output
978 = 8 M / (1022 x N) Î N = 8 M / 978 x 1022 = 8
20 = 100 x OCR1x / 511 Î OCR1x = 102.2 Î OCR1x = 102
85 = 100 x OCR1x / 511 Î OCR1x = 434.35 Î OCR1x = 434
.INCLUDE "M32DEF.INC"
SBI
SBI
LDI
OUT
correct PWM
LDI
OUT
L1:
L2:
PORTB,0
DDRD,5
R20, 0x82
TCCR1A, R20
//mode 2, non-inverted phase
R20, 0x02
TCCR1B, R20
//N = 8
SBIS PINB,0
RJMP L2
LDI
R20, HIGH(434)
OUT
OCR1AH, R20
LDI
R20, LOW(434)
OUT
OCR1AL, R20
RJMP L1
LDI
OUT
LDI
OUT
RJMP
R20, HIGH(102)
OCR1AH, R20
R20, LOW(102)
OCR1AL, R20
L1
//pull-up resistor
//PD5(OC1A) as output
//if PINB.0 is 0 then jump L2
//duty cycle = 85%
//when key is closed
//duty cycle = 20%
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Chapter 17: SPI PROTOCOL AND MAX7221 DESPLAY
INTERFACING
SECTION 17.1: SPI BUS PROTOCOL
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
False
True
True
False
True
True
True
False
In a 3-wire interface bus, we have SCLK and CE, and only a single pin for data transfer
but in SPI, we have SCLK and CE, and 2 pins for data transfer; MISO and MOSI.
To distinguish between the read and write operations, the D7 bit of the address byte is
always 1 for write, while for the read, the D7 bit is LOW.
SECTION 17.2: SPI PROGRAMMING IN AVR
11.
12.
13.
14.
15.
False
SPSR, SPCR and SPDR
SPI mode 2 means Read on falling edge and changed on a rising edge. According to
Table 17-1, CPOL = 1 and CPHA = 0. CPOL and CPHA are bits 3 and 2 of SPCR
register.
True
True
SECTION 17.3: MAX7221 INTERFACING AND PROGRAMMING
16.
17.
18.
19.
20.
21.
22.
23.
24.
24
Pin 19
300 mA
True
10 kilohm
8
The first byte (MSBs) of each packet contains the command control bits
The second byte is the data to be displayed
False
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Chapter 18: I2C PROTOCOL AND DS1307 RTC INTERFACING
SECTION 18.1: I2C BUS PROTOCOL
1.
2.
3.
4.
5.
6.
7.
8.
9.
True
False
True
True
True
False
True
True
In SPI, we have SCLK and CE, and 2 pins for data transfer that are called MISO and
MOSI. But is I2C, we have SCK for clock and a single data pin that is called SDA.
10. The eighth bit in the packet is the READ/WRITE control bit. If this bit is set, the
master will read the next frame (Data) from the slave, otherwise, the master will write
the next frame to the slave.
SECTION 18.2: TWI PROGRAMMING IN AVR
11. True
12. Bit rate generation unit, bus interface unit, address match unit, and control unit.SPI
mode.
13. bus interface unit
14. True
15. Bit0 and bit1
16. TWIE
17. By clearing the TWEA bit to zero.
SECTION 18.3: AVR TWI PROGRAMMING IN ASSEMBLY AN C
18.
#include <avr/io.h>
void i2c_init(void)
{
TWSR=0x00;
// set prescaler bits to zero
TWBR=0x47;
// SCL Frequency is 50K for XTAL=8M
TWCR=0x04;
// Enable the TWI module
}
//**********************************************************
void i2c_start(void)
{
TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
while ((TWCR & (1 << TWINT)) == 0);
}
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//**********************************************************
void i2c_write(unsigned char data)
{
TWDR = data ;
TWCR = (1<< TWINT)|(1<<TWEN);
while ((TWCR & (1 <<TWINT)) == 0);
}
//**********************************************************
unsigned char i2c_read(unsigned char isLast)
{
if (isLast == 0)
//if want to read more than 1 bytes
TWCR = (1<< TWINT)|(1<<TWEN)|(1<<TWEA);
else
//if want to read only one byte
TWCR = (1<< TWINT)|(1<<TWEN);
while ((TWCR & (1 <<TWINT)) == 0);
return TWDR ;
}
//**********************************************************
void i2c_stop()
{
TWCR = (1<< TWINT)|(1<<TWEN)|(1<<TWSTO);
}
//**********************************************************
int main (void)
{
unsigned char i = 0 ;
i2c_init();
//initialize TWI for master mode
i2c_start();
//transmit START condition
i2c_write(0b01101001);
//transmit SLA + R(1)
i=i2c_read(1);
//read only one byte of data
i2c_stop();
//transmit STOP condition
i2c_start();
//transmit START condition
i2c_write(0b01101010);//transmit SLA + W(0)
i2c_write(i);
//write the byte of data
i2c_stop();
//transmit STOP condition
while(1);
//stay here forever
return 0 ;
}
19.
#include <avr/io.h>
// Standard AVR header
void i2c_initSlave(unsigned char slaveAddress)
{
TWCR = 0x04;
//enable TWI module
TWAR = slaveAddress;
//set the Slave Address
TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWEA);//init TWI module
}
//*********************************************************
void i2c_send(unsigned char data)
{
TWDR = data;
//copy Data to TWDR
TWCR = (1<< TWINT)|(1<<TWEN);
//start transmission
while ((TWCR & (1 <<TWINT))==0); //wait to complete
}
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//*********************************************************
void i2c_listen()
{
while ((TWCR & (1 <<TWINT))==0); //wait to be addressed
}
//*********************************************************
int main (void)
{
i2c_initSlave(0b01101000);//init TWI module as
//slave with address
//0b0110100 and do not
//accept general call
i2c_listen();
//listen to be addressed
i2c_send('Y');
//transmit ‘Y’ letter
while(1);
//stay here forever
return 0 ;
}
SECTION 18.4: DS1307 RTC INTERFACING AND PROGRAMMING
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
8
pin 4
pin 8
True
True
True
2099
It provides one of 1 kHz, 4 kHz, 8 kHz, or 32 kHz frequency if enabled.
input
RS1, RS0 and SQWE
64
When Vcc falls below the Vbat level
Address location 0x00 is assigned to seconds, address location 0x01 is assigned to
minute and address location 02 is assigned to hours and AM/PM
33.
Address location 0x03 is assigned to day(of week), address location 0x04 is
assigned to day of month (date), address location 0x05 is assigned to month and
address location 0x06 is assigned to year
34.
By setting D6 of hour location (location 0x02) to high, we switch to AM/PM
mode
35.
By clearing D6 of hour location (location 0x02) we switch to 24 hours mode
36.
0x06
37.
0x3F
38.
True
39.
Here only the changed lines of program 18-11 are mentioned and other lines are
the same.
i2c_start();
i2c_write(0b11010000);
i2c_write(0);
//transmit START condition
//address DS1307 for write
//set register pointer to 0
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i2c_write(0x05);
i2c_write(0x15);
i2c_write(0b01101001);
i2c_stop();
40.
Here only the changed line of program 18-12 is mentioned and other lines are the
same.
i2c_start();
i2c_write(0b11010000);
i2c_write(0x04);
i2c_write(0x14);
i2c_write(0x05);
i2c_write(0x09);
i2c_stop();
41.
//set seconds to 0x05 = 05 BCD
//set minutes to 0x15 = 15 BCD
//set hour=09 in 12 hours mode
//transmit STOP condition
//transmit START condition
//address DS1307 for write
//set register pointer to 4
//set day to 0x14 = 14 BCD
//set month to 0x05 = 05 BCD
//set year to 0x09 = 09 BCD
//transmit STOP condition
Here only the changed lines of program 18-13 are mentioned and other lines are
the same.
DDRB = DDRC = 0xFF;
i2c_start();
i2c_write(0xD1);
i2c_read(1);
PORTB = i2c_read(1);
to PORTB
PORTC = i2c_read(0);
to PORTC
i2c_stop();
//Ports B and C are output
//transmit START condition
//address DS1307 for read
//read second, return ACK
//read minute, return ACK, Send BCD value
//read hour, return NACK, Send BCD value
//transmit STOP condition
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