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RF430CL331H: When set speed at 848kbit I2C NACK

Part Number: RF430CL331H

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?



  • Hello Brown,

    It might be a timing issue, depending on what I2C timing you use. Please refer to chapter 4.9.2 in the datasheet for I2C timing specification. The host controller has to meet the ISO14443 timing convention. The typical operation flow is explained in chapter 5.9 of the datasheet. You can also compare to the firmware examples, listed in chapter 4.1.2 of the FAQ document.

    Best regards,