I have STM32F411E-DISCO board which has on-board st-link which i used before without problems (also programming external stm's). Today i tried to program STM32F103C8T6 with SWD connector (CN2) on Discovery board without success.
After that i put jumpers (CN3) back to connect with STM32F411 and it refused to connect with error "STLink USB communication error" in ST-LINK Utility which never happend before (for F4).
What i checked:
I've already checked diodes D3 and D1 voltages and seems correct, LEDs LD2 and LD1 are bright red. Programing ic seems not damaged because despite of getting little warm after while (but not really hot), ST-Link Utility returns its serial number and firmware version but fails to detect stm32 target.
Im bit confused because it looks like programmer is fine but still fails to connect any stm32. What should i check to identify source of error and possibly to fix it?
Edit 1: After some digging i found trace.log, it confirms detection of st-link and after second try to connect gives some usb error.
After more extensive search i found out that when st-link tries to connect, SWDIO actually works but nothing is sent because SWCLK is always pulled low, and do not send any clock "pulses". Im guessing that my ST-Link SWCLK pin is burned and is hard pulled low.
Also checked target and it seems ok, another ST-Link connects to it just fine. Last question, is it possible that anything else could be burned instead of pin?
Because im looking in schematics (page 29) and i do not see anything bringing me hope.