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Associate II
October 2, 2025
Solved

STM32H7 programming w/out STLINK

  • October 2, 2025
  • 3 replies
  • 341 views

Hiya. This is my first time working with custom STM PCBs.

I was planning on flashing/programming my custom STM32H7 board (specifically STM32H7A3RGT6) over STLINK and then just do general purpose programming over the USB-C COM Port. However, the TAG connector pitch was the wrong size so I'll need to find an adaptor to connect that to the STLINK module I have.

I was wondering if there is anything I can do in the meantime to program the board? The SWO/SWDIO/SWDCLK pins are broken out and I have a Nucleo L432KC. Are there any guides or tutorials for me to follow for this kind of thing?

Any help is much appreciated :).

Best answer by Andrew Neil

@f3l1xa88077 wrote:

I was wondering if there is anything I can do in the meantime to program the board? The SWO/SWDIO/SWDCLK pins are broken out


If the pins are broken out, just connect to them!

A TAGConnect is just a passive connector/adaptor - there's nothing active or special in it.

 

PS:

It would be worth also connecting NRST - that can get you out of some tricky situations ...

3 replies

mƎALLEm
Technical Moderator
October 2, 2025

Hello @f3l1xa88077 and welcome to the ST community,

The second method (not for live debug) is to use the system bootloader: AN2606 "Introduction to system memory boot mode on STM32 MCUs" / Section: 57 STM32H7A3xx/7B3xx/7B0xx devices and Table 125 that provides the interfaces/hardware available for that purpose.

"To give better visibility on the answered topics, please click on ""Accept as Solution"" on the reply which solved your issue or answered your question."
Ozone
Principal
October 2, 2025

A simple DIY custom adapter ?

You would need to check the user manual of the Nucleo L432KC, to see what jumpers / solder bridges are to change to use the onboard ST-Link for an external board.

Andrew Neil
Andrew NeilBest answer
Super User
October 2, 2025

@f3l1xa88077 wrote:

I was wondering if there is anything I can do in the meantime to program the board? The SWO/SWDIO/SWDCLK pins are broken out


If the pins are broken out, just connect to them!

A TAGConnect is just a passive connector/adaptor - there's nothing active or special in it.

 

PS:

It would be worth also connecting NRST - that can get you out of some tricky situations ...

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.
Associate II
October 3, 2025

Hiya. I've been able to connect my custom H7 board to my STLINK with some breadboard wires, but I'm having issues with actually connecting to the chip.

23:25:25 : ST-LINK SN : 0029003F3333511731363730
23:25:25 : V3J15M7
23:25:25 : Connected via SWD.
23:25:25 : Connection mode : Normal.
23:25:25 : Debug in Low Power mode enabled.
23:25:25 : Can not connect to the target!
23:25:26 : Unexpected error

f3l1xa88077_0-1759505648794.png

 

I've tried swapping pins around to see if I connected them incorrectly, but I only get "Connected via SWD" with the proper connection.

NRST is pulled high and I have my 2.2uF caps on VCAP.

Any ideas?

mƎALLEm
Technical Moderator
October 3, 2025

Are you using ST-LINK utility? 

Please use STM32CubeProgrammer tool instead. STLINK utility was deprecated since a while.

"To give better visibility on the answered topics, please click on ""Accept as Solution"" on the reply which solved your issue or answered your question."