ntag i2c plus nt3h2211 goes to undefined state

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ntag i2c plus nt3h2211 goes to undefined state

Contributor I

I am working on the NT3H2211 along with the PIC24 micro.

communication between micro and nfc through i2c works normally, but suddenly its stop working, read write on nfc dose not work through the i2c interface.

after communication stop if i2c status register of the pic24 is checked it indicates that the master bus collision is detected. 

communication starts working only after the control is power cycled.

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NXP Employee
NXP Employee


You can try the I2C Soft Reset feature when the I2C is in the undefined state.  By default, the feature is disabled so it will require a write to enable.


Here is a description of the I2C Soft Reset:

  • The I2C soft reset feature interprets an I2C repeated start (no I2C stop in between) as a command to execute a soft reset of the I2C subsystem. This is useful when heavy bus interference can cause the I2C interface to get stuck. A drawback of this feature is that every start symbol then has to be terminated with a Stop, slowing down communication. If a Stop is forgotten, the I2C interface is cleared and previous communication, if any, is lost. Consequently when this feature is used, stop conditions after MEMA for READ/ WRITE (see Figure 18) and after REGA for READ/WRITE registers (see Figure 19) shall be send.

More information is available in the NTAG I2C datasheet:


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