How to resolve a problem with ST-Link/2 not connecting to target

[Duggan.Robert]

I have been working with the trial version of the IAR IDE and with the STM32 processor family.

I have been using the ST-Link/2 device to connect to my target for debugging with no problems.

I began having a problem when starting debug, I am getting a message for the driver:

Fatal error: ST-Link, No MCU device found / Session Aborted!

I've tried updating the ST-Link firmware and reinstalling the driver but no luck.

I've also installed the ST-Link Utility and this does not connect either. I find the same problem with several ST-Link devices and all target boards. 

However, a Nucleo board does function properly.

Does anyone have any suggestions?

[Uwe Bonnes]

Did you try connect under reset? Try also other combinations of debugger/target if you have access to more devices.

[Duggan.Robert]

Thank you Uwe. I have tried three different types of target board (all operated with ST-Link/V2 dongle previously.)

The ST-Link Utility will communicate with the dongle, but not with any target connected.

[Tesla DeLorean]

Check that the ST-LINK can see and report the Target Voltage, pin 1/2 need to see power.

Strap BOOT0 high to observe if the part is responsive when executing ROM code.

[S.Ma]

Strapping boot network is useful if the user code is in stop mode. A simple workaround to reduce this pb is in the user code to delay going to power mode after reset so you have a time window to connect...

[Duggan.Robert · Accepted solution]

Thank you Gentleman. The problem was, indeed, with the power supply!

[Tesla DeLorean]

Well that, but also stuff like configuring the pins very tight in the ResetHandler. It is a diagnostic method to rule out user code, and a lack of NRST pin connectivity.