Cannot connect SWD J-link GDB Server to STM32 MCU in stop mode

[dadman]

Posted on January 31, 2014 at 17:50

Hi all,

I wrote a small program for testing a STM32L152CBT6 Stop Mode via command PWR_EnterSTOPMode(PWR_Regulator_LowPower, PWR_STOPEntry_WFI).

The program switches to stop mode immediatelly after MCU starts and after 4 seconds the RTC clock IRQ wake up the MCU.

This sequence runs in while(1) cycle and writes via SWO ITM_SendChar sentences ''going to stop...'' and ''wake up''.

Everything works perfectly well BUT after I've disconnected SWD J-Link GDB Server it is not possible to connect again :-(.

The Segger J-link GDB server just writes:

3,3V 

...

Connecting to target...ERROR...Could not connect to target

Target connection failed. GDB Server will be closed.

...and GDB server finishes running.

I've tried various reset types in J-Link, J-LinkSTM32 for reset the MCU to default state but with no success.

I think the Debug engine is not running in stop mode and the J-Link GDB server cannot detect the target.

Please help me how can I reset the MCU a flash or erase the program in memory.

Thanks

jdx

#swd-stop-mode-stm32

[chen]

Posted on January 31, 2014 at 18:01

Hi

Try this:

Use Boot0 and DFU to re-flash a different binary into the STM32 (one that does not put the STM32 into stop mode!).

[dadman]

Posted on January 31, 2014 at 18:36

Do you think is it enough to just set boot0 to High which disables loadsing the program form flash memory and use SWD to write the program into the flash memory?

[chen]

Posted on January 31, 2014 at 18:40

Hi

I hope so.

I think the problem is that your program is putting the processor into stop mode.

The debugger cannot connect to the processor because it is stopped.

[dadman]

Posted on February 01, 2014 at 18:43

YES!!! It works!. 

So, the solution is:

- Set BOOT0 pin HIGH (in my case floating was enough)

- Now the MCU is ''connectable'' by SWD

- Flash working program

- Disconnect MCU

- Set BOOT0 to LOW

Done!

Thanks a lot!