M24SR i2c communication protocol features

[vadim2]

Posted on May 19, 2016 at 10:47

I am currently developing NFC-powered device, based on Arduino and M24SR02 dynamic NFC tags. 

https://github.com/rena2019/ArduinoM24SR

 was chosen for establishing communication between Arduino and M24SR, and it works pretty fine with short NDEF messages. But I have noticed strange behavior, when reading  long NDEF messages. After reading ST documentation following questions appeared:1) What is the purpose of DID field ?2) Is it necessary to answer to S(WTX) ?3) Who an when can send S(WTX) command?Any help will be appreciated.

[JP Miller · Accepted solution]

Posted on June 30, 2016 at 11:23

Hello,

1/ The DID field is a Device Identifier that a NFC Forum Device can use to simplify addressing of a target device. On the I2C host side, the DID is not used for the M24SR02 tag and therefore can be coded to 0. 2/ S(WTX) is generated by the M24SR02 in case M24SR02 will take more time to complete a transaction requested by the I2C host. In this case the I2C host must answer with a S(WTX) response. Best Regards, Have a good day. NFC Product Support 3