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Hariom
Associate III
January 19, 2026
Solved

STM32WBA5MMGH6TR Debug interface PCB layout

  • January 19, 2026
  • 2 replies
  • 239 views

I am using STM32WBA5MMG in my design. This the development board schematic. Below image is from development board schematic.

Hariom_1-1768823941790.png

As per the constrains , SWDIO and SWCLK must be length matched. Also need to provide a shield.My questions are given below.

  1. SWDIO and SWCLK are not differential lines, why length matching is required for them.
  2. By shield did they mean routing SWDIO and SWCLK on top of a solid GND plane
Best answer by Andrew Neil

I found a description of these in the STLINK-V3SET User Manual:

AndrewNeil_1-1768825064221.png

https://www.st.com/resource/en/user_manual/um2448-stlinkv3set-debuggerprogrammer-for-stm8-and-stm32-stmicroelectronics.pdf#page=24

 

 

2 replies

Andrew Neil
Andrew Neil
Super User
January 19, 2026

These are not usual requirements for SWD !

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.
H
HariomAuthor
Associate III
January 19, 2026

May I know what you mean by GNDDetect and KEY JRCLK signal?

Andrew Neil
Andrew NeilBest answer
Super User
January 19, 2026

I found a description of these in the STLINK-V3SET User Manual:

AndrewNeil_1-1768825064221.png

https://www.st.com/resource/en/user_manual/um2448-stlinkv3set-debuggerprogrammer-for-stm8-and-stm32-stmicroelectronics.pdf#page=24

 

 

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.
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