ST25R3916 Select/SEL_REQ CL1 values
I'm working on writing drivers to use an ST25R3916B to interface with a non-ST host chip as an NFCIP-1 passive communication initiator. I've made progress on the communication to establish an active connection to a tag, but one part I'm stuck on is the response from the SEL_REQ CL1 command message. I'm expecting a 1-byte SAK, but instead I get a 3-byte response: 0x04 0xDA 0x17. When I ignore this response and move to the next stage of anticollision, I do then receive the next 4 bytes of the UID as expected.
What do the bytes 0x04 0xDA 0x17 mean in this case? Is it some information about the ST25R3916B's communications or the tag's contents? I looked through the RFAL for reference but could not find any information about the CL1 response, only the command. Any clarification would be appreciated.