STM32G071G8U6 Flashing Issue – MCU Not Detected via SWD

[a18k]

Hello, I'm experiencing a flashing issue with an STM32G071G8U6: STM32CubeProgrammer (ST-LINK, SWD, Normal mode) returns "Unable to get core ID" / "No STM32 target found", even though the measured target voltage is correct (~2.93–2.97V, see attached screenshot). I'm also attaching the MCU pinout and SWD connector schematics for reference. I'd like to know what possible causes could explain a total loss of SWD communication despite the correct current voltage, and whether there's a test that could confirm an internal MCU failure before concluding the component needs to be replaced.

 

Best regards

 

[MM..1]

Check your PCB, is realy yellow SWCLK connected into red net name SWCLK ??.. And change mode of connect to under reset.

[Karl Yamashita]

Check with an oscilloscope to see if you are getting some clock/data signals at the STM32. If it’s a BGA type then i hope you have some series resistor close to the MCU for debugging. Make sure the wave form are nice and square and not skewed.

I would test without the TVS and also bypass the series resistor. The 100 ohm resistor might be to high of a value? I’ve only seen a couple of Nucleo-H7xx boards that use TVS and series resistor at 22 Ohm. All other Nucleo boards have no protection at all.