Smart card issue

lgiordano · ‎2016-10-17

Posted on October 17, 2016 at 23:01

Hi all,

I get ATR fine.

However, when I send any command, the reply is ''my command+reply''. I mean, it looks like the Smart Card is echoing my command (however it doesn't, I can see the transmission on a logic analyzer). Maybe the UART is ''receiving'' while it is sending? Of course I can chop the extra bytes received, but it is not standard.

Thanks in advance.

Leonardo

#smartcard

Tesla DeLorean · ‎2016-10-17

Posted on October 18, 2016 at 01:33

Well it is a single wire interface, so unless you disable the RX on the USART you're going to see the data you send

Tips, Buy me a coffee, or three.. PayPal Venmo
Up vote any posts that you find helpful, it shows what's working..

lgiordano · ‎2016-10-18

Posted on October 18, 2016 at 14:58

Hi clive, tks for reply.

I guess that is happening. As I'm using uclinux, I'm not sure if I will be able to send command while rx is disabled, and enable reception after tx has been done, as the card start replying just after receiving command. Maybe my workaround removing echo is better.

On an Atmel processor this echo doesn't happen, so I got confused. Datasheets don't state anything about this behaviour.

Regards,

Leonardo