Use nucleo-64 ST-Link debugger for another MCU

vernture · ‎2025-09-12

Removed the ST-Link plastic jumpers and all four pins are free now - as shown on the blue rectangle. As well as, the yellow rectangle shows the 6 pins of CN4 on one column.

It seems that pins 1 and 3 are 3.3 V and GND respectively based on the use manual (https://www.st.com/resource/en/user_manual/um1724-stm32-nucleo64-boards-mb1136-stmicroelectronics.pdf)

but when I check those two pins using a multimeter I get no voltage! Any idea where is the issue?

mfgkw · ‎2025-09-12

There are some light weight NUCLEO-32 boards.

The minimum board from ST I ever had is a STM32G0316-DISCO for ~ 12€.

https://www.st.com/en/evaluation-tools/stm32g0316-disco.html

If this has not enough IOs then look for NUCLEO-32...

Andrew Neil · ‎2025-09-12

@vernture wrote:
Blue wire: from 3V3 (blue pill) => pin 1 of CN4 = VDD_TARGET
Green wire: SWDIO (blue pill) => pin 4 of CN4 = SWDIO
Brown wire: SWCLK (blue pill) => pin 2 of CN4 = SWCLK
Yellow wire: GND (blue pill) => pin 3 of CN4 = GND
Wight wire: R (blue pill) => pin 5 of CN4 = NRST

I've marked-up the CN4 pin names in blue - that all looks correct.

One possible problem is that NRST is still connected to the STM32F411RE on the Nucleo board - again, breaking-off the ST-Link would remove all doubt.

But, as @mfgkw said, the device on a Blue Pill is almost certainly not a genuine STM32 - so trouble is (almost) to be expected; eg, see:

https://community.st.com/t5/others-hardware-and-software/configuring-uart-on-stm32f103c8t6-bluepill-kills-connection-to/m-p/668641/highlight/true#M32234

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

Andrew Neil · ‎2025-09-12

@mfgkw wrote:
NUCLEO-32 ..

+1.

Also, I think SMT32-based boards from Adafruit or Sparkfun should be trustworthy - and at least you will get support from them:

https://www.adafruit.com/category/52 - but note that the ST-Link shown there is a clone.

https://www.sparkfun.com/sparkfun-thing-plus-stm32.html

Also Olimex.

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

vernture · ‎2025-09-12

I understand that breaking off the Nucelo can remove possible issues and is also easier to use the ST-Link but I'm not going to do that "now" because there're some connections between the st-link and the nucleo board at the back of the board and I only have this original board and don't want to damage it.

Suppose you use only some specific protocols in your project, e.g., you use I2C and a timer to make a PWM for your modules, so if you have a small and minimal sized board capable of doing these (a blue pill does these and more) you can pack all the devices (including the board) into a small size box, suitable for external uses (like the small devices you see in the market that do lots of things)

The issue with a blue pill, despite its cool features mentioned above, is that it's not genuine mostly, and it can be the case for any non-Nucleo board, I suppose. Ofc, there might be blue pills with a genuine mcu on it (where to order it or more importantly how to figure out if a blue pill drives such an mcu?)