ST25DV04 NFC I2C communication problem if ST25DV04 all time under Reader.

[Vladimir Kharakh]

Posted on August 10, 2017 at 13:52

ST25DV04 NFC I2C communication problem if ST25DV04 all time under Reader. There are cases (one per tens of minutes) that communication on I2C and RF is closed together and there is no way to reset if ST25DV04 to normal state. Recommended I2C long 'start condition' not solve problem. How I can reset chip in this case.

#st25dv04-nfc-i2c

[Rene Lenerve]

Posted on August 21, 2017 at 17:30

Hi Vladimir,

I tried to duplicate your problem but I did not succeed, after waiting a lot of time with a reader and i²c communication.

The only way to reset the ST25DV is by turning off the power (VCC off, and remove the reader or cut off the field).

The I²C timeout on Start only resets the I²C block and not the ST25DV.

Can you detail your configuration (power supply, reader type, commands send when it breaks communication, ...) in order to reproduce it.

Best Regards.

[Vladimir Kharakh · Accepted solution]

Posted on August 22, 2017 at 16:38

Hi,

Problem solved!  

We use ST25DV04 (8 pin) on place of  M24LR04E. Recommendation  for M24LR04E hardware schematic in

 AN4125 (Figure 10)   NOT PROVIDE  Power Up conditions for 

ST25DV04  1V/us (ST25DV04

  datasheet p.22

). 

Instead  recommended  resistor 10 ohm was installed resistor 100 ohm. 

Thanks