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TM4C1294NCPDT: TM4C129 - How to get 0% and 100% duty cycles?

David Bai
Intellectual 1835 points
Part Number: TM4C1294NCPDT

Hi team,

Is there anyone knows how to get 0% and 100% duty cycles PWM based on TM4C129? Or are there any examples to produce 0% duty cycles (always Lo) and 100% duty cycle (always Hi) signals? Thanks a lot.

  • 0
    Guru 117855 points

    Obtaining such "EXTREME value" (100 % or 0% Duty) PWM has always proved a challenge for (many) such ARM designed MCUs.

    Both "add-on" hardware - as well as "added" software may resolve:

    • Hardware - employ a gate such that the MCU's "normal" PWM signal may be "blocked" (thus yielding 0% duty) or "forced high" (yielding 100% PWM)
    • Software - add code to detect (either) 0 or 100% duty - and reconfig the PWM output pin to GPIO - then clearing (0%) or setting (100%).     When a non-extreme duty is required - switch back to PWM config.

    It should be noted - that most often - most "external devices" will "accept" 99% PWM Duty and 1% PWM Duty - as alternatives for either "Extreme Values."    Many ARM vendor devices suffer this limitation...