Trouble with ST-LINK/V2 debugger

[John Griswold]

I'm feeling really stupid about this. We were unable to debug in our circuit, so to check, we have a standalone STM32L021D4Px, mounted to a solderless breadboard. 3.3V is connected to Pin 14, ground to pins 9 and 1, NRST to pin 4, SWDIO to pin 13 and SWCLK to pin 14.

The debugger does not see the target. The Keil IDE sees the ST-LINK/V2 OK.

Clearly I'm missing something. Can anybody tell me what I'm missing?

Thanks

[Tesla DeLorean]

Odd, the firmware can be down graded

[John Griswold]

After several house of looking I am unable to find any firmware. Do you happen to know where ST keeps it?
Thanks

[Tesla DeLorean]

This is v2.27.15

https://drive.google.com/open?id=0B7OY5pub_GfITE82bnBza2RCbEE

[John Griswold]

Thank you, but apparently they don't like downgrading the firmware:
13:08:59 : Error: Old ST-LINK firmware version. Upgrade ST-LINK firmware
13:09:14 : Error: OLD ST-LINK firmware, please upgrade it before trying to reconnect
At least it allowed me to upgrade again! Back to square zero.
Just for my own edification, where did you find this? Do you just keep a repository of everything ST releases? 🙂

[John Griswold · Accepted solution]

DOH! I knew it was going to embarrass me when the truth became evident.

We have the isolated version of the ST-LINK/V2. Of the 9 GND pins on the connector, five of them cannot be used for GND because they are disconnected or otherwise purposed.

I moved the GND signal from Pin 4 to Pin 20 and voila!

Thanks, Clive. You're the balls.

[Tesla DeLorean]

I archive stuff, it provides historical context to issues, and allows problems to be regression tested. One of the policies the people I work with have is to archive design documents, so design decisions can be reviewed with contemporary documentation.