Can I use the ST-LINK V3 of a Nucleo-144 to flash an external MCU?

[Ce3c]

My board is the NUCLEO-H743ZI2, I've looked in the manual but haven't found anything so far. Maybe I could remove jumper JP2 so the Nucleo's MCU stays powered down and then connect the CN2 connector (SWD) to the external MCU?

Thanks!

[mfgkw]

It is obviously not intended to use the ST-Link from that board for an external application.

I'm afraid that the H743 still connected may inhibit communication or make it unreliable - but you might give it a try.

Besides connecting CN2 you will need NRST, which can be stolen at JP1 hopefully.

Maybe an external ST-Link/v2 or /v3 may be a better solution, or a another NUCLEO board providing its ST-Link for external targets. See also https://community.st.com/t5/stm32-mcus-products/stm32533re-programming-with-nucleo-st-link/m-p/830964

If it works as you suggest it would be nice to leave a note here...

[Ce3c]

Ok thanks. I haven't even started PCB design yet but was trying to figure out whether I should add an ST-link to my order list. I'll get one and try both ways, it'll be a while before I report back here.

[STTwo-32 · Accepted solution]

Hello @Ce3c 

The ST-LINK V3 embedded on Nucleo-144 boards cannot be used to flash or debug an external MCU. The design of the ST-LINK V3 on these boards is specifically tailored for the onboard MCU and does not support external programming or debugging.

Best Regards.

STTwo-32

[Tesla DeLorean]

I'd recommend adding a 10-Pin ARM SWD header or 20-Pin ARM JTAG Header to your board to facilitate debugger connectivity. The latter with the 0.1" pitch might be easier to hook up if you can afford the space.

An external ST-LINK/V2 or ST-LINK/V3SET might be best choice, avoid third-party clones.

Older NUCLEO-64 / 144 boards also have a SWD connection point, and can disconnect the local Target via a pair of jumpers.