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Application with two STM-32 MCU and one STLINK-V2 port (to one of the MCUs) - cascading possible?

wb0gaz
Senior

An application will use two STM-32 MCUs - for purpose of this posting, I'll call them "outer" (it's SWDIO and SWCLK pins can be attached to a STLINK-V2 device for firmware downloading), and "inner" (it's SWDIO and SWCLK pins would be tied to two GPIO pins of "outer", and not be externally accessible.)

My question is this - is it possible (by a combination of firmware running on "outer" and appropriate settings to STLINK-V2 such as an acceptable clock frequency) to have the "outer" MCU provide a transparent path (using as-yet undefined firmware running on "outer") so that STLINK-V2 attached to outer's SWDIO/SWCLK pins is passed bit-for-bit to the two GPIO pins (on "outer") which would be connected to SWDIO/SWCLK of "inner" MCU?

The intent of this is to avoid having two separate connectors to which STLINK-V2 would be attached for debug and firmware delivery, and not be reliant on a bootloader (that is, the "inner" processor could be reloaded from scratch using STLINK-V2.)

Happy to answer any request for clarification and be guided in different direction if need be.

Thanks

1 ACCEPTED SOLUTION

Accepted Solutions
TDK
Guru

On newer families the hardware capability exists, although I don't think the st-link firmware supports it yet.

On the F0 series, definitely not.

https://community.st.com/t5/stm32-mcus-boards-and-hardware/swd-multidrop-does-any-stm32-or-st-link-support-it/td-p/80861

https://community.st.com/t5/stm32-mcus-products/swd-multi-drop-support-on-stm32l4/m-p/80394

 

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2 REPLIES 2
TDK
Guru

On newer families the hardware capability exists, although I don't think the st-link firmware supports it yet.

On the F0 series, definitely not.

https://community.st.com/t5/stm32-mcus-boards-and-hardware/swd-multidrop-does-any-stm32-or-st-link-support-it/td-p/80861

https://community.st.com/t5/stm32-mcus-products/swd-multi-drop-support-on-stm32l4/m-p/80394

 

If you feel a post has answered your question, please click "Accept as Solution".
wb0gaz
Senior

Thanks so much for the pointers!