NT3H2211 usage as EE storage and passthrough mode "serial" communications

[len_]

Our design requires use of the NTAG NT3H2211 for "serial port replacement" communications as well as general purpose non-volatile storage from the I2C side.

We wish to ensure priority access to EEprom memory from the I2C bus over NFC passthrough mode comms, but I am having difficulties getting access to EEprom memory from the I2C bus while the NTAG is in passthrough mode - i.e. an I2C NAK.

I have tried disabling passthrough mode and trying to force I2C bus access, by writing to the session registers (PTHRU=0 I2C_LOCKED=1) at the point in tame that an EEprom access is necessary. This only works some of the time.

How do I gain access to EEprom memory from the I2C bus no matter what state the chip is in i.e. override the ARBITER completely?

Any other thoughts on the use of this device for both these requirements would be appreciated.

[Jonathan_Iglesias]

Hi  @len_ 

can you please confirm you are following the AN https://www.nxp.com/docs/en/application-note/AN11579.pdf

here you can see an explanation on how to use the pass through mode and share information from NFC to i2c and other information that might be helpful for your applicaiton.

Have a great day !

BR

Jonathan

[len_]

Hey Jonathan

Firstly, thanks for the reply - I have had this issue for a while and cannot find a solution.

Yes, I have used the AP note you mention. In fact the NFC pass-through comms to Windows is working well.

The problem is the access of the NTGA EEprom (2nd 1k of 2k device) that we are using for general purpose non-volatile storage when performing NFC pass-through comms at the same time.

For example, when receiving a message from NFC, processing the message may require a rd/wr of the EEprom, before sending the response over NFC. At this time, I find that I get a NAK from the NTAG sometimes. I have tried switching pass-through mode off and forcing I2C bus access to no avail, as follows:

  //disable pass-through mode and enable I2C access (FAILS SOMETIMES)
  ntag_SetTransferDir(NTAG_I2C_TO_RF);
  ntag_SetPthruOnOff(FALSE);
  uc_err = ntag_RegSessSet(NTAG_REG_NS_REG, NTAG_NS_REG_MASK_I2C_LOCKED,   NTAG_NS_REG_MASK_I2C_LOCKED);

I am looking for a reliable method of gaining access to EEprom from I2C no matter the current state of the chip.

Len