Tool/software:
Hi,
I was using TM4C129ENCPDT development board for one of my project.It was working fine but after i flashed the code(which was working fine) i am not able to reprogram or erase the chip .Could some one please help me out to fix this.
Hi,
What type of code did you load to the flash? If you happen to create a program that does one of the following then you could lock out the JTAG access.
1) a program that puts the device in low power mode such as deepsleep or hibernate. When a device enters one of those power modes, the clocks are stopped. Without a clock, the JTAG debug probe is unable to synchronize with the debug logic on the processor. When developing a lower power application, you must have a mechanism to wake up the device to run mode. If the device cannot be woken up then you will not be able to connect to the device.
2) a program that re-purpose the JTAG pins for GPIO. JTAG pins on the device can be reconfigured for GPIO. If this is done, then JTAG emulator cannot connect to the device anymore.
Normally you can unlock the device to its original factory settings. You can use either LM flash programmer or Uniflash to unlock the device. Refer to the instructions on section 5.3.1 in this app note. https://www.ti.com/lit/pdf/spma075
You can also if the unlock is complete by checking the MAC address. LaunchPads have the MAC address pre-programmed. If you successfully unlock the device the MAC address would have changed to all F's if you click on the 'Get Current MAC address'.
