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MFRC522 strange behaviour

Question asked by Dietrich Wall on Oct 5, 2016
Latest reply on Oct 13, 2016 by Dietrich Wall


I have to implement an authentication application with an MFRC522 ver 02 Mifare reader. The reader is connected via I2C to a MSP430 Microcontroller. The first tests were successfull, i´m able to read the Version register. But reading other registers returns values which are not documented in this way. For example: reading the CommandReg register returns 0x3F, Datasheet mentions a reset value of 0x20.


Write accesses into internal Registers are also accepted and acknowledged from the chip. But when i´m trying to read out the written values, the initial values do not change. 

The only register value that seems to be ok is the VersionReg Register(Adress: 0x37, Value 0x92)

What could be the reason for this behaviour?

Thx in advance