st25r3911b VHBR ISO 14443A

[memo]

st25r3911b in 14443A mode

TX: BITRATE_848

RX: BITRATE_1695

tx is successful，when  receive , switch B mode  , but  fail  :CRC error ,soft framing error and hard framing error

how can I solve this problem or Which registers still need to be modified?

[Ulysses HERNIOSUS · Accepted solution]

Hi,

ST25R3911B supports only VHBR for ISO14443B. Although modulation scheme of A VHBR and B VHBR are the same, however the frame format is different (A VHBR having parity bits and CRC_A, where as B VHBR having start and stop bits and CRC_B).

I think you will not be able to succeed this way. Only if you would dive into transparent mode and let MCU do everything.

BR, Ulysses

[memo]

I see,Thank you.

[Ulysses HERNIOSUS]

Hi,

to clarify this: VHBR is possible in B only. Tx in fc/8, fc/4, fc/2. Rx in fc/8 and fc/4. DS11793 rev7 is incorrect in this aspect.

BR, Ulysses

[memo]

Thank you very much.

Are there any other RF chips that support VHBR in both modes A and B in reader mode?

Another question is that we have difficulties in waveform shaping when trimming the matching network of 3911 reader mode. There was a roughly 700mV overshoot in A waveform and very low modulation index in B waveform. We used the ST matching tool for the matching component value calculation. Do you have any suggestions for the further work.

Best Reagards.

[Ulysses HERNIOSUS]

Hi, 

I am not aware of any other chips supporting VHBR. And especially none for  A VHBR.

Waveshaping on ST25R3911B basically needs to be done through matching: Play with lower Q / play with different EMV inductors, ....

For modulation index you will need to adapt dram bits. Or use the direct command.

BR, Ulysses

[memo]

I will try your suggestion. Thank you!