Smart Card interaction with ACR122U

Question

I'm trying to write an application that will interact with smart cards using an ACS ACR122U card terminal. According to all that I can find the API uses a combination of standard APDU commands and psuedo-APDUs to interact with the terminal, however psuedo-APDUs don't seem to work as claimed.

The API Reference (provided on the ACS site) indicates that APDUs of the form "FF XX XX XX ..." will be interpreted by the terminal (rather than sent to the card) but I always get a response status of "6E XX" (which I interpret as me sending an invalid class ID). I've tried sending commands to flash the LEDs on the terminal using "FF 00 40 0F 04 00 00 00 00" and also tried to get some unique identifier from the card using "FF CA 01 00".

I can't find anything useful within the ISO 7816-4 document (the standard for smart cards) and the API reference provided by ACS. Also, ACS are not very forthcoming with information. Does anyone have any ideas as to what I may be doing wrong or where I might look for additional information?

I can get an ATR - Answer To Reset from the terminal when a card is connected. I'm developing for interaction with Mifare 1K cards and would like to read from them and interact with the LEDs and buzzer on the terminal.

Answer 1

You can retrieve the API documentation here. This is ACS' proprietary APDUs so don't refer to standard ISO-7816 specification. Refer to section 6 for pseudo-APDU requirements.

To simulate LED, refer to section 6.2 for details and appendix E for example. You may try changing your APDU as follow: FF 00 40 FF 04 0A 0A 03 03. Please note that I set the LED control and also put non-zero values for LED duration.

For the second APDU, refer to section 4. Please note that you are missing P3/Le in your APDU (shall be FF CA 01 00 00) and you need the card reader connected with PICC.