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pt70
pt70
Associate
February 16, 2022
Solved

SWD multi drop support on STM32L4

  • February 16, 2022
  • 2 replies
  • 4461 views

Hi all.

I'd like to know if STM32L4S5 and STM32L432 support SWD multi drop (SW-DP v.2 protocol).

Thank you in advance.

Best regards,

P.

This topic has been closed for replies.
Best answer by Uwe Bonnes

You can find out by decoding the DPIDR. Here for a G474, no L4 at hand:

Read Core ID: 0x2ba01477

DPIDR 0x2ba01477 (v1 rev2)

2 replies

TDK
TDK
February 16, 2022

There's this post saying the STM32H7 has multi-drop support:

https://community.st.com/s/question/0D50X0000AIdZjnSQF/does-the-stm32h750-support-multidrop-swd

But it's not mentioned in any reference documents or promotional material for the H7. Unsurprisingly, the L4 documents don't contain any information either.

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Uwe Bonnes
Uwe Bonnes
Chief
February 16, 2022

DP on L4 is V1. Multidrop support needs DP V2.

TDK
TDK
February 16, 2022
I am not doubting you, but where did you obtain this information? Can you see it when you connect with debugger or something?
"If you feel a post has answered your question, please click ""Accept as Solution""."
Peter BENSCH
Peter BENSCH
Technical Moderator
February 16, 2022

@TDK​ The older reference manuals did not contain this yet, but the new ones already contain the note in the section Debug Infrastructure: The SWJ-DP implements SWD protocol version 2, if it is included.

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