A reader-programmer will allow you to study in depth all the smart cards that comply with the ISO 7816 specifications. Within this category we can highlight the cards used in mobile telephony, also called SIM, or those used in payment services, also called prepaid cards. or smart access. KIT 25 KIT 25 list of component sIn this article we will focus on cards of the first type, that is, GSM cards, also called SIM cards. This is due to the fact that we will find more entertainment in this type of cards for two apparent reasons. One because it is one of the most widespread, see mobile phone, and another because we will have the option of editing the content of these in a totally legal way. Remember that SIM cards contain within them the ability to store phone numbers or short messages. The exhaustive use of these data is what makes us constantly resort to editing them. In this case, far from falling into the boredom of the keyboard of the mobile phone itself, we will use the PC, in order to increase efficiency and speed. Remember that it is much easier to edit, copy and paste from a PC than to delete and create the same data from the telephone keyboard. For all this we will rely on powerful Software and the Gift Kit that you can get here. hardware The hardware for reading and writing to SIM cards is pretty straightforward. Remember that we limit ourselves to SIM cards for personal reasons. This means that with this Hardware you can also read any type of card that complies with the ISO 7816 standard. Now, without further ado, let's proceed to describe the electrical diagram of this assembly. As you can see, all the logic revolves around a single integrated circuit. It is a 74HC04 type inverter. Inside this Microchip we can see up to six inverter gates, five of which are used in this assembly. But to simplify things even more, we will focus on the different signals obtained from the Sub 9 connector, which in turn are necessary for handling the SIM. Basically we are talking about the Reset lines and the Tx and Rx channels, since the Clock signal is generated in the electrical circuit itself. The Tx and Rx signals terminate at a common point and that is the SIM card I/O pin. This means that we are facing a bidirectional port, that is to say that synchronized data enters and exits through the same line. These data are clearly differentiated on pins 2 and 3 of the Sub 9 connector. The data that is sent from the PC to the I/O pin of the SIM previously passes through an NPN type transistor in inverter mode and the return is transferred to through one of the 74HC04's reversing gates. KIT 25-3 The Reset signal is also obtained from the Software running on the PC and is delivered to two inverter gates before the signal is applied to the SIM Reset pin. For the clock, whose frequency is 3.579545Mhz, a quartz crystal is used together with two inverting gates, which together with two low-capacity capacitors are capable of resonating the quartz. The power supply of the SIM card is obtained from the sum of the voltage of the DTR and RTS lines. Two NPN type transistors allow the passage of this supply voltage while it is indicated by a LED that will only light up when the serial port is open. That is, when there is voltage at least in the DTR line. As you have seen, the circuit is quite simple and practical. Some characteristics of this assembly is that it uses a high Reset to work, as well as the DTR line for Hardware control is ignored. The software KIT 25 fig 1 and 2On the Internet there is a series of ideal Software to read and write to SIM cards, but after a careful selection we have selected Cardinal 68 for its high stability with this Hardware. Remember that we are limited to a reset high and the deprecation of the DTR line as conditional. However we can remind you here, that the present setup is also able to work with other SIM editing software. The only condition is that they do not use identification ID when starting. Small user manual In our practices we have chosen, as you will remember, Cardinal 68-. This Soft is quite simple to use, but we will explain something about it, so that you become familiar with its functions more quickly. Initially, it should be remembered that to start Cradinal 68 you must double click on the cardinal.exe file, after which the main interface of this Software will be displayed. I am going to summarize david so that you can understand me in a more practical language the correction of the internal configuration of each sim card is done by layers and you test if the layer and the test work you have to apply it as an update to the total of the u sims to be able to continue modifying the following layers and obtain a final result, we cannot apply changes to only one batch since each configuration, for security and reader reasons, once the change works, we must apply the layer card by card. That is why my recommendation is the physical presence of all the teams and all of us with their respective SIM cards. I understand the time zone and the fact of not being able to be in your technical service at night, what we can do is plan a methodology of I work with batches of 20. Let me know if this information is useful to you. Today we establish a connection. Greetings. lee sung technical service and support manager
