How to write data into st25dv04k using i2c ?

[Mpraj.19]

i am trying to write data using i2cset function of linux but when i write 00 value to 0x01 and read same addreess it returns me 00 value.

root@var-som-mx6:~# i2cset -y 2 0x53 0x00 0x01

root@var-som-mx6:~# i2cdump -f -y 2 0x53

No size specified (using byte-data access)

    0 1 2 3 4 5 6 7 8 9 a b c d e f   0123456789abcdef

00: 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

40: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

50: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

60: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

70: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ................

root@var-som-mx6:~#

[JL. Lebon]

​Hello,

Please be aware that memory addresses are coded on 2 bytes in the ST25DV04K. You may try 0x53 0x00 0x00 0x01 (the 0x00 0x00 are the memory address pointer and 0x01 is the data to be written).

Best regards.

[Ronald B. · Accepted solution]

Hello Mpraj.19,

From my understanding, you cannot use i2cset and i2cdump to consistently access the ST25DV-I2C memory, because this device requires 2 bytes for internal address (while these commands only accept 1 byte of register address).

Maybe the first byte written of i2cset could be used as the 2nd addressing byte, but this trick cannot work for the i2cdump.

Also, the ST25DV-I2C as an internal address counter and when you do an "i2cdump -f -y 2 0x53" you're actually reading from this internal address counter (and not from offset 0).

Please note as well that after a write the internal address counter poinst to the next address after the one that was written.

However I'm pleased to let you know that we just released the STSW-ST25DV007 software package providing a Linux user space driver for the ST25DV-I2C, available here:

https://www.st.com/content/st_com/en/products/embedded-software/st25-nfc-rfid-software/stsw-st25dv007.html#overview

This software package comes with a User Manual for easy ramp-up.

Regards