TM4C123 ISO7816 mode

Hiroyasu Tazawa1

Guru 12350 points

Hi, Everyone

I need your help.
We use TM4C123x UART ISO7816 mode.

This datasheet says TM4C support for communication with ISO7816 smart cards.
and Stop bit is 2 if ISO7816 mode is used.

I understand Tiva's frame is

-Start bit 1 bit
-Data bit 8 bit
-Parity bit 1 bit
-Stop bit 2 bit

Total 12 bit

but ISO7816 frame is defined by total 11bit.

Can TM4C123x get 11 bit frame (stop bit is 1) if some device transmit 11bit frame?

Best Regards
Hiroyasu

over 10 years ago

0 Amit Ashara over 10 years ago

TI__Guru**** 244440 points

Hello Hiroyasu,

No, it is supposed to be 12 etu

www.smartcard.co.uk/tutorials/sct-itsc.pd

Regards
Amit

0 Hiroyasu Tazawa1 over 10 years ago in reply to Amit Ashara

Guru 12350 points

Hi, Amit

Thank you for your Reply.
My customer says 12 etu is a part of ISO7816.

ISO/IEC 7816-3:2006 says

read.pudn.com/.../ISO%2BIEC%207816-3-2006.pdf
11.2 Character frame

Denoted CGT, the “character guard time” is the minimum delay between the leading edges of two
consecutive characters in the same direction of transmission. If N = 0 to 254, CGT = GT as specified in 8.3.
If N = 255, CGT = 11 etu in both directions of transmission.

and Customer's SIM Card is N=255.
They need to get CGT=11etu.

Can Tiva get CGT=11etu ?

Best Regards
Hiroyasu

0 Amit Ashara over 10 years ago in reply to Hiroyasu Tazawa1

TI__Guru**** 244440 points

Hello Hiroyasu,

No it is not possible for the 11 etu. The user must rely on N=0 to 254 for the 12 etu.

Regards
Amit

0 Hiroyasu Tazawa1 over 10 years ago in reply to Amit Ashara

Guru 12350 points

Hi, Amit

Tnank you. I got it.
and Can TM4C129x get 11etu ?

Regards
Hiroyasu

0 Amit Ashara over 10 years ago in reply to Hiroyasu Tazawa1

TI__Guru**** 244440 points

Hello Hiroyasu

No the 11 etu is not possible as there is no sub mode selection. You may attempt checking 7 bit instead of 8 bit word, but not sure if that will work.

Regards
Amit

0 Hiroyasu Tazawa1 over 10 years ago in reply to Amit Ashara

Guru 12350 points

Hi, Amit

Thank you.
I got it.

Hiroyasu

0 Hiroyasu Tazawa1 over 10 years ago in reply to Hiroyasu Tazawa1

Guru 12350 points

Hi, Amit

Could you tell me Why Datasheet says Support for communication with ISO 7816 smart cards ?
TM4C can not support 11etu.

Best Regards
Hiroyasu

0 Amit Ashara over 10 years ago in reply to Hiroyasu Tazawa1

TI__Guru**** 244440 points

Hello Hiroyasu

Because 12 etu is also a supported mode in ISO7816 which is what TM4C supports. The other option is to use timer with GPIO (effectively bit banging to emulate the protocol)

Regards
Amit

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TM4C123 ISO7816 mode