ST25DV04K: I2C and RF Communication not working

[RSing.6]

Hi there,

I am new with St25dv04k NFC

I want to send data from RF to I2C using ST25DV04K IC by following AN4910

I have followed all the procedure as written in the Application note. I am getting the interrupt but unable to transfer the data from the NFC tag.

I also tried using the ST25 NFC tap Android application to write data on the IC using RF and I2C

Thanks in advance have a nice day ST community is awesome.

[JL. Lebon]

Hello,

Can you tell us a little bit more details about your problem ?

When you say you are unable to transfer the data from the NFC tag, what are you doing to read the data from the tag ?

Some suggestions to start debugging:

• It's already a good point if you can get the interrupt. It means that probably the message from RF has been written into mailbox correctly.
• Are you able to read the message in mailbox from RF ? if there is a message from RF in the mailbox, you should be able to read it back from RF.
• Is your I2C communication working fine (i.e. are you able to read user memory from I2C ?)
• Have you read the MB_CTRL_Dyn register to check that there is a message in the mailbox from RF ? (bit RF_PUT_MSG should be 1, or at least RF_CURRENT_MSG should be 1).
• Have you read the MB_LEN_Dyn register to check the number of bytes present in the mailbox ?

Best regards.

[RSing.6]

Basically I want to read and write NFC tags using this ic, but i am not able do that.

[RSing.6]

What is actual difference between ST25DV04K and CR95HF

I think ST25dv04k is not able to read and write NFC Tag stickers which don't have power.

Please help.

Thank you.

[JL. Lebon · Accepted solution]

Hello,

The CR95HF is a NFC reader. It can read and write NFC tags. Basically, it generates a 13.56MHz magnetic field to power NFC tags, and communicates with them by modulating the 13.56MHz magnetic field.

The ST25DV04K is a NFC tag. It can be read by a NFC reader. It is a passive component (on its RF interface side) that needs to be powered by an external 13.56MHz magnetic field to be read and written. Compared to other NFC tags, the ST25DV04K also have a second interface, the I2C interface, and can be read and written by a microcontroller through this I2C interface as well.

So, you can't read another NFC tag with a ST25DV04K, since it is also a NFC tag. To read other NFC tags, you must use a NFC reader (CR95HF, ST25R3911...).

Hope this help you.

Best regards.

[RSing.6]

Thank you for the help. I am now using CR95HF. For further help, I will contact you.

Best regards