Hi all,
I have trouble executing Protocol Parameter Selection (PPS), trying to
change N parameter (extra guard time).


Actually, I have a card that can support both T=0 and T=1. I am trying
to switch to T=1, and since TC1 in ATR is 'FF', i.e. card support
minimum delay for transmission,
I'd like to set N for card and terminal to use 11 ETUs per char.

I am giving this PPS : FF 31 96 01 59
1) PPS = 0xFF             -- PPS
2) PPS0 = 0x31            -- T=1, PPS1 and PPS2 present
3) PPS1 = 0x96            -- F = 512, D = 32
4) PPS2 = 0x01            -- 11 ETU for T=1 should be activated
5) PCK = 0x59

After this card never responds (I can see this on SIM analyzer)  - it
just block communication.

I tried with PPS2 0x00, 0x01, 0x02 and 0x03. All the same error - card
does not respond.

I think that these values are correct because standard says :

PTS2 indicates the support of N=255, when bit b1 is set to 1. Bit b1 set
to 0 is the default and indicates that the 11 etu period is not used. If
bit b2 is set to 1, the card shall use an extra guardtime of 12 etu for
its transmssion of characters to the interface device. Bit b2 set to 0 is
the default and indicates that no extra guardtime is required. Bit b3 to
b8 are reserved for future use.


If PPS2 is not used in PPS, cad accepts T=1 and protocol and F and D
parameter change and continues communication normally.

However, I can see with analyzer that card is using 11 ETUs for
encoding although I did not pass it PPS2 = 0x01, and by the standard
this should say : 11 ETU not used.

What seems to be the catch ? Why the PPS blocks. Why is card using 11
ETUs in character encoding by default (1 guard char) ?


Best regards,
Drasko
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