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TM4C1294NCPDT: How to lock USER_REGx permanently?

Rickey Chien
Prodigy 175 points
Part Number: TM4C1294NCPDT

Hi Sir, 

We'd like to keep the User Register0-3(USER_REGx) and make the register is not changeable by client. 

Can you advise is there any way to lock the user register permanently?

Thank you. 

  • 0
    TI__Guru**** 183066 points

    Hi,

      The User Registers0-3 are stored in non-volatile memory. These registers are write-once registers. Once committed, it can not be changed unless going through a 'unlock' operation which will perform a mass-erase to the factory setting. 

       

  • 0 in reply to Charles Tsai
    Prodigy 175 points

    Hi Charles, 

    Thanks for your reply. According to your information, the USER_REGx can be unlocked for reprogramming. 

    But can you advise is there any way to lock the user register permanently? 

    Thank you. 

  • +1 in reply to Rickey Chien
    TI__Guru**** 183066 points

    Hi Rickey,

       The user registers are one-time programmable only. No one can write to the user registers the second time. The only way to program the user registers again is to unlock the device. Therefore, if someone wants to write the user registers again, it will not work, nothing will happen. This is indirectly a way to lock the registers permanently, isn't?  As I mentioned, an "unlock" operation will erase the entire device, not just the user registers but the entire flash memory and EEprom that stores will program and data. It is a "soft" way to destroy the device.