FRDM-MCXA156: SWO Trace (Data, Profile & Interrupts) Not Working in MCUXpresso IDE

[sidsal]

Hello Everyone,

I am currently working with the FRDM-MCXA156 development board and have been facing an issue with SWO (Serial Wire Output) while debugging.

Although the application debugs successfully, I am unable to receive any data in the SWO Trace windows, including:

• SWO Data
• SWO Profile
• SWO Interrupt Trace
• SWO ITM Console

To troubleshoot the issue, I have already verified the following:

• The SWO pin has been correctly configured using Config Tools.
• The TRACE clock is enabled and configured to 96 MHz, matching the MCU core clock (MCXA156 runs at 96 MHz).
• The project is being debugged using LinkServer with the on-board MCU-Link probe.

Despite these configurations, all the SWO trace windows remain empty during debugging.

For reference, I have attached screenshots of the SWO Trace Configuration, SWO Data, SWO Profile, and other windows, along with the relevant project configuration.

I would greatly appreciate any guidance or suggestions on what might be causing this issue or if there are any additional configuration steps required to enable SWO trace on the FRDM-MCXA156.

Thank you for your time and assistance.

#swo #frdm-mcxa156 

[Alice_Yang]

Hello @sidsal 

For the FRDM-MCXA156 board, resistor R36, which connects the SWO signal to the onboard debugger, is DNP (not populated) by default. Could you please populate R36 and test again?

Alice_Yang_0-1786344510075.png

Thank you.

BR

Alice

[sidsal]

Thank you for pointing this out @Alice_Yang . I checked the FRDM-MCXA156 schematic and confirmed that R36, which connects the P0_2/SWO signal to the onboard MCU-Link debugger, is marked as DNP.

I also noticed that on the FRDM-MCXN947, the equivalent SWO connection (R130) is populated with a 0 Ω resistor. Could you please confirm whether R36 on the FRDM-MCXA156 should also be populated with a 0 Ω resistor to enable SWO tracing through the onboard MCU-Link debugger?

Additionally, could you please clarify why R36 is left unpopulated (DNP) by default on the FRDM-MCXA156? Is there a specific board-design reason or limitation that requires it to remain unpopulated? So I cannot use SWO feature? 

Thank you for your help.

[Alice_Yang]

Hello @sidsal 

" Could you please confirm whether R36 on the FRDM-MCXA156 should also be populated with a 0 Ω resistor to enable SWO tracing through the onboard MCU-Link debugger?"

->>Yes. If you want to use the SWO function, you need to install a 0 Ω resistor or solder the connection accordingly.

“Additionally, could you please clarify why R36 is left unpopulated (DNP) by default on the FRDM-MCXA156? ”

->>I think this is because not all users require the SWO function, so the 0 Ω resistor is not populated by default.

Thank you.

BR

Alice

[sidsal]

Thank you for your support @Alice_Yang .

[sidsal]

With respect to previous thread,

The screenshot of SWO enable configuration and clocks are attached below.

Thanks