Question about BitFraming during anti-collision Loop

[supcik]

Hello,

I have a question regarding this line and the following one from the file MFRC522v2.cpp (lines 671 and 672):

// Set bit adjustments
rxAlign = txLastBits;
_driver.PCD_WriteRegister(PCD_Register::BitFramingReg, (rxAlign << 4)+txLastBits);

As far as I understand (and according to the comment), txLastBits is : "The number of valid bits in the last transmitted byte." This means the for the next transmission, we need 8 - txLastBits bits from the last byte. So I would define the BitFramingReg with :

_driver.PCD_WriteRegister(PCD_Register::BitFramingReg, (rxAlign << 4) + ((8 - txLastBits) & 0x7));

I have no doubt that the current implementation works, but it might do a couple of additional iterations in the anti-collision loop. Or am I misinterpreting something?

Thank you in advance for your reply.

[supcik]

My other observation is that the BitFraming register is written at line 672, but then you call the method PCD_TransceiveData (line 675), which calls the method PCD_CommunicateWithPICC (line) which also writes the BitFraming register (line 391). So I think that the first write to the BitFraming should not be needed.