I.MX RT1050 PWM waveform accuracy is not correct

[shaozhongliangs]

My customer tried to generate some PWM outputs working on the i.MX RT1050. But the PWM waveform accuracy is not correct. I reproduced this issue with  i.MX RT1050 EVKB, using demo code $\boards\evkbimxrt1050\driver_examples\qtmr\inputcapture_outputpwm in SDK. It should probe a 50Khz PWM signal output with 50% dutycycle. The oscilloscope shows the PWM output  at pin J23-5 accuracy was about 49.7K.

[jeremyzhou]

Hi S.z. Liang,

Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
After testing, both of two compare values need to minus 1 after calculating, so please use the adapted codes to replace the original code in the QTMR_SetupPwm() function.

    /* Setup the compare registers for PWM output */
    base->CHANNEL[channel].COMP1 = lowCount-1;
    base->CHANNEL[channel].COMP2 = highCount-1;

    /* Setup the pre-load registers for PWM output */
    base->CHANNEL[channel].CMPLD1 = lowCount-1;
    base->CHANNEL[channel].CMPLD2 = highCount-1;‍‍‍‍‍‍‍

Have a great day,
TIC

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