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MSPM0L1304-Q1: Clarification on PA20/SWCLK Pin Functionality

Santosh Patil
Prodigy 10 points

Part Number: MSPM0L1304-Q1

We are currently using the M0L1304QDGS32RQ1 (VSSOP package) microcontroller from TI in our design.

Could you please confirm whether the PA20/SWCLK pin can be used for both programming/debugging and analog input functionality?

Please refer one proposed schematic beloe.

Please share your feedback and suggest any necessary modifications.

 

  • 0
    TI__Expert 8465 points

    Hi Santosh,

    Yes, in VSPA20, pin 27 on the 32-pSOP package, supports both SWCLK and ADC0 input A6, but not simultaneously. Your pin assignment is correct. See datasheet Table 6-1.

    For your design:

    • Firmware: To use A6, disable SWD using DL_SYSCTL_disableSWD(), configure PA20 for analog operation with its internal pulls disabled, and select ADC channel 6. Active debugging is unavailable afterward.
    • Hardware: R207’s 4.7 kΩ resistance does not isolate HB_RCOD_uC from SWCLK. Provide a jumper or analog switch to disconnect the analog source during programming/debugging. During ADC operation, disconnect the debugger or ensure its SWCLK output is high impedance.
    • Recovery: SWD is restored only by a power-on reset. Include a startup delay or recovery mode that prevents firmware from immediately disabling it again; alternatively, retain a validated BSL recovery path. See Development Guide §7.3.

    If you need to measure HB_RCOD_uC while debugging, revise the pin allocation so that its ADC input does not share SWCLK. Hope this helps!

    -Brian

  • 0
    Prodigy 10 points

    Hi Brian, 

    Thanks for the reply.

    Regarding firmware point, we want to read analog pin at startup only. So is it possible to disable SWD and enable again after reading analog pin?

    -Santosh