CMSIS Debugger Debug Settings from dbgconf are not taken into account

[FerdinandEn]

Type: Bug Report

Describe the bug

• OS and Version: Win 11
• VS Code Version: 1.101.0
• Extension Version: Arm CMSIS Solution 1.54.0 / 2.10.0
• Extension Version: Arm CMSIS Debugger 0.3.1
• Target Device: STM32F746ZGTx

To Reproduce
Steps to reproduce the behavior:

1. Change .cmsis/CubeMX+STM32F746ZGTx.dbgconf
2. Select Debug MCU APB1 freeze register (DBGMCU_APB1_FZ) -> DBG_TIM6_STOP
3. New value-> DbgMCU_APB1_Fz = 0x00000010;
4. Error: In file CubeMX+STM32F746ZGTx.cbuild-run.yml Debug-Var value is unchanged __var DbgMCU_APB1_Fz = 0x00000000;

Expected behavior
Value should be __var DbgMCU_APB1_Fz = 0x00000010;

I have changed the variable content in CubeMX+STM32F746ZGTx.cbuild-run.yml to __var DbgMCU_APB1_Fz = 0x00000010;

After starting the debugger, the DbgMCU_APB1_Fz register still has the value 0.

Code sample and logs

0000622 I Target type is stm32f746zgtx [board]
0000837 I DP IDR = 0x5ba02477 (v2 rev5) [dap]
0000840 I debugvar 'DbgMCU_APB1_Fz' = 0x10 (16) [cbuild_run]
0000840 I debugvar 'DbgMCU_APB2_Fz' = 0x0 (0) [cbuild_run]
0000840 I debugvar 'DbgMCU_CR' = 0x7 (7) [cbuild_run]

[jkrech]

Please note that the values from the *.dbgconf files are not processed by the csolution and therefore do not show in the cbuild-run.yml file. Instead the *.cbuild-run.yml files include a reference to the *.dbgconf file:

debugger:
    name: ST-Link@pyOCD
    protocol: swd
    clock: 10000000
    dbgconf: .cmsis/USB_Device+STM32U585AIIx.dbgconf
    gdbserver:
      - port: 3333

According to the CMSIS Pack Specification configfile is a:

Configuration file with path relative to the package base folder (extension *.DBGCONF). This file contains assignments of a default value to global debug access variables. This file gets copied to the project folder and is editable by the end-user. This file is read by the debugger after processing the global debug access variables. By editing the values of the debug access variables, the end-user effectively controls the behavior of sequences. The file can only assign new values but must not specify any new debug access variables. Configuration Wizard Annotations shall be used within the file to provide a graphical user interface for editing configuration options.

Therefore it is the responsibility of pyOCD to read the dbgconf files and override the default values specified.

Have you tried to read the register value after the debug connection is established?

[FerdinandEn]

Thanks for pointing out that changes to dbgconf do nothing in the CubeMX+STM32F746ZGTx.cbuild-run.yml file.

The problem is that the changed value is not displayed in the Peripherals view of the debugger. If you query the register directly in the debug console with :

*0xe004200B

you obtain the set value. In my case 24 (DBG_TIM5_STOP & DBG_TIM6_STOP).

As soon as I try to change the value in the Peripherals window, the automatically set value is not modified but completely overwritten. If I select DBG_TIM6_STOP, for example, I then get the value 16. The DBG_TIM5_STOP bit has been deleted.

It seems to be a general problem of the debugger that register contents are displayed incorrectly in the peripherals window.

[jkrech]

I am using version 1.8.0 of the CDT Peripheral Inspector that was released 2025-06-13 and I do not seem to be able to replicate the above described problem. What other debug related extension do you have activated for your current profile?

[FerdinandEn]

I am using the same version. The program is very simple. It is a test program to check whether the tools have been installed correctly. I use the Nucleo-F746ZGT board. You can also test it with the Nucleo-F756ZGT board without any modification.

ToolTestKeilStudio.zip

[FerdinandEn]

I have found my mistake. I need to activate refresh mode.

[jkrech]

For the sake of clarity for other people, you are referring to the settings of the CDT's Peripheral Inspector VS Code extension settings:

vscode://settings/peripheral-inspector.periodicRefreshInterval
and
vscode://settings/peripheral-inspector.periodicRefreshMode

Can this issue be closed or do you think the overview documentation should be explicit about this setting in addition to the usual documentation of extension settings?

[FerdinandEn]

Thanks for your help. The issue can be closed from my side. Is there a trick how to open the memory inspector for a variable? I have only succeeded via:

> memory: Show Memory Inspector

I used &Variable to specify the address of my variable. I then also selected the Variables column. However, I could not find any display of my variables in the column.