nfc_t4t_lib

[MarcinT]

Hi,

My problem is that reader sends PPS command (both DRI & DSI set to 0) for which there is no response/confirmation from library, and I don't know how to implement this response because in raw mode library passes through only I-blocks to application layer. Library lack of response to PPS prevents me from entering ISO14443-4 I-block exchange. Is there any way to overcome this, or own driver needs to be build on the basis of nrfc_nfct ?

Regards,

Marcin  

[Kenneth]

With static DR and DC announced in the TA(1) octet of ATS frame, the Reader should know PPS is not supported and it shouldn't send the PPS so the problem is rather on the reader side.

Adding support for PPS is not possible as it would require support for dynamic bitrate changes, which the NFCT HW is not capable of.

Kenneth

[MarcinT]

Hi, Thanks for the prompt reply, meanwhile I wrote my own driver and it performs quite well. I just noticed one strange phenomena (maybe not very important) - communication with the reader looks like below: 

0 | 1056 | Rdr | 26 | | REQA
2244 | 4612 | Tag | 44 00 | |
134576 | 137040 | Rdr | 93 20 | | ANTICOLL
138228 | 144052 | Tag | 88 1a 1b 1c 95 | |
275568 | 286096 | Rdr | 93 70 88 1a 1b 1c 95 c0 45 | ok | SELECT_UID
287284 | 290804 | Tag | 04 da 17 | |
460832 | 463296 | Rdr | 95 20 | | ANTICOLL-2
464484 | 470308 | Tag | 1d 1e 1f 2a 36 | |
603760 | 614288 | Rdr | 95 70 1d 1e 1f 2a 36 22 61 | ok | ANTICOLL-2

and so on...

but I noticed that when I try to send one byte (04) + (da 17) CRC calculated in nrf52840, then RX_FRAMEEND event causes that I read 95 70 ... so it looks like the second byte comes from the previous reader's frame)

When I try to send (04 da 17) - this is without CRC calculation in nrf52840 then everything is OK.

In both cases I call  nrfx_nfct_rx(...) in TX_FRAMEEND event where easyDMA is initialized for Rx.

On the other hand, I didn't notice any problems when Tx/Rx buffers are separate (or in case of longer - non 1 byte+crc frames).

Regards,

/Marcin

[Kenneth]

Sounds like a race condition, e.g. NFC Easydma fetch data asynchrounuos to the CPU interrupt do update/read the data. Using separate buffers sounds like a good idea.