1 (edited by allosev 2015-05-17 08:54:56)

Topic: Time delays between NFC tag commands cause a problem on ACR122

Hello, Guys!
The problem occures when I introduce "significant" (only few seconds) amount of time delay between NFC tag commands.
I'm working on a program with GUI interface for NFC tags testing which has separate buttons for commands (REQA/WUPA, ANTICOLLISON/SELECT, HLTA, etc). When I click the buttons quickly (less than 2 sec between clicks) all works fine otherwise I get the problem - tags are mute. I'm sure there is no problems with the tags.
To check that the problem is not in my program I introduced delay into nfc-anticol.c example between REQA and ANTICOLLISION commands using sleep() function. The nfc-anticol does not work properly when delay >= 2 sec:

memcpy(abtAtqa, abtRx, 2);
// Anti-collision
transmit_bytes(abtSelectAll, 2);

My configuration:
ACR122U (use acr122_pcsc driver)
Windows 7 64bit
last version of libnfc

Any suggestions? smile

Re: Time delays between NFC tag commands cause a problem on ACR122


I'm not sure but I could be related to ACR122...
Again, I repeat : ACR122 is not a good NFC device: some firmware are bogus, a MCU do "too much" thing on front of NFC chip (ie. reset NFC chip in certain condition, for example polling)

Romuald Conty