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March 16, 2026
Question

TARGETSEL problem with multidrop on STM32WL and U0

  • March 16, 2026
  • 1 reply
  • 295 views

I am trying to do multidrop with STM32WL5MOC and STM32U031. I have some issues:

[1] When WL5MOC is the only active MCU in the circuit (U0 is not powered on) I cannot connect M4 core using TargetSel=0x04970041 option:

  • I can connect to M0+ core using tagetsel (STM32_Programmer_CLI -c port=swd TargetSel=0x04970041 ap=1 mode=hotplug)
  • If I try the same with ap=0, CLI cannot connect to M4 core and retires with ap=1 and then connects M0+ core again
  • There is no issue when not using targetsel option and U0 is disconnected. I can connect both WL5 cores with ap=0 and ap=1 options.

[2] If I power on U0 and try multidrop, I cannot connect any of the cores of WL5:

  • I can connect U0 with targetsel option(STM32_Programmer_CLI -c port=swd TargetSel=0x04590041 ap=0 mode=hotplug).. At first CLI cannot connect with ap=0 and retries with ap=1 and then connects.
  • Interestginly If I try ap=1 directly, it cannot connect to U0 (STM32_Programmer_CLI -c port=swd TargetSel=0x04590041 ap=0 mode=hotplug)

Am I missing something?

 

1 reply

barmaganAuthor
Associate
March 16, 2026

Additional Info:

I am using latest sw and fw:

  • STLINK-V3PWR with firmware V4J7B3P6
  • STM32CubeProgrammer v2.22.0

Also tried mode=hotplug/ur/normal

Aziz BRIGUI
Technical Moderator
March 17, 2026

Hi @barmagan

This is a known limitation for STM32CubeProgrammer v2.22.0, you can find more details here: STM32CubeProgrammer errata 2.22.x - stm32mcu.

Our team is working internally for a fix. I'll let you know if there's any updates (Internal tracking number: TPRG-91).

Aziz

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barmaganAuthor
Associate
May 21, 2026

Hi @Aziz BRIGUI 

Is there any progress on this subject?

 

Regards,

B.