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how to disable the swd program read in tm4c1294

rubin lee
Prodigy 210 points

Hi,

we designed a board using tm4c1294, and program via SWD, using Jlink. then the program comes:

the jlink have ability to read entire chip's hex code out, how could i disable reading once i have burned the chip? 

besides, i wish the chip can be write again, but it should never be read out. 

  • 0
    TI__Guru**** 244400 points
    Hello Rubin,

    The simplest approach is to convert JTAG pins into GPIO prohibiting the read of the device. The second approach is to use the BOOTCFG register's DBG pins to a value like 00. This will also block a JTAG read. However to get back access, the only solution will be to toggle-mass erase the device, which will ensure that the device is not able to send the hex code as it shall be erased.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Prodigy 210 points

    thaks for your help, in the reply, you said:
    However to get back access, the only solution will be to toggle-mass erase the device, which will ensure that the device is not able to send the hex code as it shall be erased.


    how could i use the toggle-mass erase to make sure the device will be erased before sending the hex code?
    can i use FlashProtectSet(), or any other method?

  • 0 in reply to rubin lee
    TI__Guru**** 244400 points
    Hello Rubin,

    Toggle Mass Erase is also called the Unlock Mechanism. The Unlock Mechanism erases all User Committed and Programmed Flash locations. FlashProtectSet will pose issue for Read mode as the code relocation for literals must be done.

    Regards
    Amit