Electronic – Make a simple sim card reader circuit

sim

I'm trying to implement a sim-card reader for my own. I followed step by step the guide on www.ladyada.net site but it does not work as it would be. My PC and softwares i used to read/write data from/to sim-card could't recognize my sim-card reader. Have someone successfully made this sim-card reader circuit? Pls help me with some ideas or show me where i went wrong. Thanks so much.
P/s: this is the circuit schematic in .png
Sim Card Reader Circuit

And this is the site i followed:
Reference Link

Best Answer

  • You said "My PC and softwares i used to read/write data from/to sim-card could't recognize my sim-card reader"
    What did you expect?
    It is a very simple terminal circuit using a RS232 interface to send and receive data. There is nothing to recognize, e.g. no reader ID...
  • Another thing you have to consider: the data line is bi-directional, i.e. there is one line for transmitted and received data. Therefore your commands sent to the card will be echoed back, which is not a problem as the terminal software knows what it has sent; but it has to be handled. I.e. the terminal software has to remove the echoed command from the received data.
  • This simple kind of reader will not be able to handle communication errors according to the T=0 communication protocol, which is used for SIM cards. According to T=0 the receiver must signal a transmission error (parity error) by pulling down the data line for 1 ETU shortly (i.e. 0.5 ETUs) after receiving the bad data frame. Standard UARTs have no possibility to do that (ETU = "elementary time unit" = duration of one bit).

You definitely can not expect any random software to be able to use your simple terminal. It has to be specialized for this reader.

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