SWV works with NUCLEO-144 USB ST-LINK but not with external ST-LINK/V2

[JuiHung]

Hi,

I’m using a NUCLEO-144 (STM32H563ZIT6) development board with only the board USB STLINK-V3EC port connected. TRACE and DEBUG are enabled with Serial Wire in the configuration file, and printf is routed through ITM:

int _write(int file, char *ptr, int len) {
 for (int i = 0; i < len; i++) {
 ITM_SendChar((*ptr++));
 }
 return len;
}

SWV is enabled in the debug configuration, the core clock is 250 MHz, and the SWV window (port 0) shows output correctly in STM32CubeIDE.

 

 

When I switch to an external ST-LINK/V2 and connect

NRST#15 / SWDIO#7 / SWCLK#9 / GND#20 / TARGET VCC#1 / VDD3.3 V#19, programming and debugging work, but the SWV window shows nothing in the STM32CubeIDE.

The reason for using ST-LINK/V2 for SWV debugging is that on our product’s onboard MCU, only VDD, NRST, SWDIO, SWCLK, and GND are exposed.

 

Could anyone explain why SWV output does not appear with ST-LINK/V2?

Thanks.

 

 

[FBL]

Hi @JuiHung 

On the 20‑pin JTAG/SWD header of ST‑LINK/V2, SWO is pin 13. Check user manual.

On nucleo board, SWO should be on the MCU pin mapped to PB3. 

[JuiHung]

Hi FBL,

 

Thanks for the reply.

I have reconfigured the DEBUG mode from Serial Wire to Trace Asynchronous SW, which enables PB3 and regenerated the code.

 

I first tested with the USB ST-LINK port on the NUCLEO-144 board, and ITM_SendChar worked via SWV in STM32CubeIDE. Then I switched to ST-LINK/V2 and added an extra connection between Pin #13 on ST-LINK/V2 and PB3 on CN12-Pin #31 or CN7-Pin#15 on Nucleo-144 board, but the SWV output still does not show.

Is there anything I might be missing?

Thanks.

[JuiHung]

It turns out that the ST-LINK pin short needs to be removed from the power source select jumper JP2 on NUCELO-144. After removing it, the SWV output works correctly when STLINKV/2 SWO is connected to CN12-Pin #31.

[Andrew Neil]

Have you checked that the onboard ST-Link is disconnected (particularly from SWO) when you're using the external ST-Link ?

[JuiHung]

It didn’t disconnect, but I didn’t connect SWO. I will check by connecting it to the board to see if I can get the output.
Thanks.