STM32G0B1CET can't connect under SWD
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‎2025-03-09 6:58 PM
Hi,
I have built a handful of STM32 designs before and never had a chip fail to connect. I can't seem to get any connection in Cube Programmer at all:
- VDD,VREF+,VBAT is at 3.3V, VSS is connected to ground.
- NRST is high at boot
- I can see current drop from 17mA to 7mA (at 12V) when pulling NRST low , so it seems like MCU is doing something.
- I originally connected with a JLINK but just bought a STLINKV3 SET with the same result.
- Using SWD over a tag connect
- tried every connect option in cube programmer (mode/reset mode)
- I see SWCLK,SWDIO, and NRST working on an oscilloscope, although I haven't bothered decoding the signals.
- I confirmed chip orientation
- I confirmed SWCLK,SWDIO, and NRST pins
- I confirmed my STLINK was updated
- Checked for shorts under microscope
Schematic:
Layout:
I am pretty much out of ideas at this point, hoping its something *** I missed and need a second set of eyes :)
Any new ideas would be appreciated!
Solved! Go to Solution.
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STM32G0 Series
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‎2025-03-15 8:57 PM
Figured it out:
I accidentally used the "STM32G0B1CET6N" instead of "STM32G0B1CET6" variant when selecting parts for the BOM. Which does not have VDDIO connected internally and instead goes to pin 20.
I (poorly) assumed anything in the option field of the part number was related to packaging info. Kind of a footgun IMO there are pin to pin compatibility differences in the last letter of a part number. My datasheet doesn't even mention it in the ordering info:
My fault regardless!
-Jakob
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‎2025-03-10 6:35 AM
I looked through everything but can't see anything wrong.
Since you probed power, and verified SWD activity, that narrows things down quite a bit. Sure there are no shorts or cold solder joints? A large in focus picture of the board may help.
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‎2025-03-10 8:15 PM
Hi TDK,
here is a picture of the board. Also I forgot to mention I had two boards assembled and they both have the same issue so I am hesitant it is a solder joint issue. I also inspected it under a microscope and it looked good, I don't have a way to capture through the microscope lens though.
Another theory I have is somehow the STM32s I received had RDP enabled?
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‎2025-03-15 8:57 PM
Figured it out:
I accidentally used the "STM32G0B1CET6N" instead of "STM32G0B1CET6" variant when selecting parts for the BOM. Which does not have VDDIO connected internally and instead goes to pin 20.
I (poorly) assumed anything in the option field of the part number was related to packaging info. Kind of a footgun IMO there are pin to pin compatibility differences in the last letter of a part number. My datasheet doesn't even mention it in the ordering info:
My fault regardless!
-Jakob
