How to share a programming port between multiple STM32U5 and STM32L4 MCUs

[y_yamamoto]

I am currently using multiple STM32U5 series and STM32L4 series MCUs in a single system.
I would like to share a single physical programming port (e.g., SWD or UART) among these MCUs and switch between them to program each one individually.

• I have already confirmed that ST-LINK cannot program multiple MCUs simultaneously.

• Based on this premise, is it possible to share a programming port between multiple MCUs and still program them individually?

• If it is possible, could you please advise on the method?

Thank you in advance for your support.

[TDK]

Can't be done with SWD. You could try JTAG.

Solved: SWD Multi Drop on STM32H5 and target instance - STMicroelectronics Community

Solved: SWD multidrop? Does any STM32 or ST-LINK support i... - STMicroelectronics Community

[y_yamamoto]

Thank you very much for your response.

I will try using JTAG as you suggested.

I have an additional question.

In section 7.4.2 "JTAG" of the following PDF, it states: " The STLINK-V3SET does not support the chaining of devices in JTAG (daisy chain)."

STLINK-V3SET debugger/programmer for STM8 and STM32 - User manual

Since I own an ST-LINK V3SET, it seems that I cannot use its JTAG interface for daisy chain connections.

Dose this mean I would need a third-party JTAG debugger?

From my research, SEGGER's J-LINK appears to be one option, but I do not currently own one, and the cost is quite high.

If there are any alternative solutions you could recommend, I would greatly appreciate your advice.

[TDK · Accepted solution]

I don't know of any alternative solutions. Multi-drop is not common.