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?

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