M24LR16E-R RF Read/Write issue

[Naveen_Kongari]

Hello Team,

I am facing RF read and write issues with the M24LR16E‑R EEPROM.

The exact problem is as follows:

• When I take a new EEPROM and write data to it using an RF NFC reader for the first time, the operation is successful.
• However, during subsequent attempts to read and write:
  • In some EEPROMs, RF read works but write fails but I2C read/Write working.
  • In some devices, both read and write operations fail but I2C read/Write working.
  • A few EEPROMs work correctly without any issues.

In our application, we are using Sector 2 and Sector 3 for user data storage.

When I read data from the problematic EEPROMs through St25 mobile application, I observe the following:

• Sector 0 and Sector 1 Security Status is 0x00. And the data read and write is working in these 2 sectors.
• Sector 2 to Sector 15 Security status:
  • Current Security Status: 0x09
  • New Security Status: 0x09

Additionally, I receive the warning:

“Sector locked. Security Status can only be changed through I2C.”

I am not sure why the security status has changed or why the sectors are locked.

Could you please provide clarification on the following points?

1. Is it possible to unlock the EEPROM once it is locked?
2. Can the EEPROM be unlocked via RF (NFC reader), or is I2C the only method?
3. What could be the possible causes for the EEPROM sectors getting locked in this scenario?

 

Thanks,

Naveen 

 

[JL. Lebon]

Hello, 

It is possible to unlock a sector, but only from the I2C interface. Once locked, a sector cannot be unlocked from the RF interface,

To unlock the sector, the I2C password must first be presented, then it is possible to write in the system area from I2C to unlock the sector.

There is no clue in what you describe that can explain why those sectors become locked. Most probably a lock-sector RF command has been issued at some point, or the sector security status byte has been programmed from I2C at some point. If you describe more your setup and what you are doing with the tag it may help understanding.

Best regards.