I am trying to transmit data from the tag to a reader. When I set the tag speed at 106kbit/s I can send data without problem, when I set the data rate to 848kbt, the RF link at 848kbit is built, and I can see the reading request from the reader from the tag side, but once the MCU starts sending data through i2c bus, the I2c becomes NACK and the data never passed to the tag chip. I can send CC file success but no NDEF file.
Is this a timing issue? What is the highest data rate of the I2C that the tag supported? Should I send data within a certain time after the tag get the reading request? Should I write the host response register before starting to send data?