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TM4C1290NCPDT: Can't get second pulse stream out of PWM

Doug Broadwell85
Intellectual 440 points
Part Number: TM4C1290NCPDT

Tool/software:

I'm trying to get two identical pulse streams out of PWM0, GEN0 and GEN2.  I get the pulses out of GEN0 at PF0 but nothing out of GEN2 at PF2.

 GPIOPinTypePWM(GPIO_PORTF_BASE, 0x01);

    GPIOPinConfigure(GPIO_PF0_M0PWM0);

    GPIOPinTypePWM(GPIO_PORTF_BASE, 0x04);

    GPIOPinConfigure(GPIO_PF2_M0PWM2);

 

    PWMClockSet(PWM0_BASE, PWM_SYSCLK_DIV_16);                                  // 1250KHz Clock.

    PWMGenConfigure(PWM0_BASE, PWM_GEN_0, PWM_GEN_MODE_DOWN   |                 //

                                          PWM_GEN_MODE_NO_SYNC );               //

    PWMDeadBandDisable(PWM0_BASE, PWM_GEN_0);                                   //

    PWMGenPeriodSet(PWM0_BASE, PWM_GEN_0, 1250);                                // 1KHz output.

    PWMPulseWidthSet(PWM0_BASE, PWM_GEN_0, 625);                                // 50% duty cycle.

    PWMOutputUpdateMode(PWM0_BASE, PWM_OUT_0_BIT, PWM_OUTPUT_MODE_SYNC_LOCAL);  // Output change on 0 count.

    PWMGenEnable(PWM0_BASE, PWM_GEN_0);                                         //

   

    PWMGenConfigure(PWM0_BASE, PWM_GEN_2, PWM_GEN_MODE_DOWN   |                 //

                                          PWM_GEN_MODE_NO_SYNC );               //

    PWMDeadBandDisable(PWM0_BASE, PWM_GEN_2);                                   //

    PWMGenPeriodSet(PWM0_BASE, PWM_GEN_2, 1250);                                // 1KHz output.

    PWMPulseWidthSet(PWM0_BASE, PWM_GEN_2, 625);                                // 50% duty cycle.

    PWMOutputUpdateMode(PWM0_BASE, PWM_OUT_2_BIT, PWM_OUTPUT_MODE_SYNC_LOCAL);  // Output change on 0 count.

    PWMGenEnable(PWM0_BASE, PWM_GEN_2);                                         //

 

    PWMOutputState(PWM0_BASE, PWM_OUT_0_BIT | PWM_OUT_2_BIT, true);             // Turn on PWM output.

Thanks, Doug

  • 0
    TI__Guru**** 184426 points

    Hi Doug,

      If you want to use PF0 and PF2 for PWM pins then you need to configure as follows.

       GPIOPinTypePWM(GPIO_PORTF_BASE, GPIO_PIN_0 | GPIO_PIN_2);

      What you had currently will first enable PF0 and later enable PF2 but disable PF0 for PWM control. 

    GPIOPinTypePWM(GPIO_PORTF_BASE, 0x01); // Enable PF0 only

        GPIOPinConfigure(GPIO_PF0_M0PWM0);

        GPIOPinTypePWM(GPIO_PORTF_BASE, 0x04); //  Enable PF2 only unless you write 0x5 in which both PF0 and PF2 are controlled by PWM module. 

        GPIOPinConfigure(GPIO_PF2_M0PWM2);

  • 0 in reply to Charles Tsai
    Intellectual 440 points

    Hi Charles,

    No, didn't fix it.  In fact even how I was initializing the ports M0PWM0 on PF0 still worked.

    Thanks, Doug

  • 0 in reply to Doug Broadwell85
    TI__Guru**** 184426 points

    Hi Doug,

      If you comment out all code associated with PF0 using GEN0, does it make a difference? let's focus on PF2 only. 

  • 0 in reply to Charles Tsai
    Intellectual 440 points

    Still no output pulse stream.

           GPIOPinTypePWM(GPIO_PORTF_BASE, 0x04);

        GPIOPinConfigure(GPIO_PF2_M0PWM2);

        PWMClockSet(PWM0_BASE, PWM_SYSCLK_DIV_16);

        PWMGenConfigure(PWM0_BASE, PWM_GEN_2, PWM_GEN_MODE_DOWN   |

                                              PWM_GEN_MODE_NO_SYNC );

        PWMDeadBandDisable(PWM0_BASE, PWM_GEN_2);

        PWMGenPeriodSet(PWM0_BASE, PWM_GEN_2, 1250);

        PWMPulseWidthSet(PWM0_BASE, PWM_GEN_2, 625);

        PWMOutputUpdateMode(PWM0_BASE, PWM_OUT_2_BIT, PWM_OUTPUT_MODE_SYNC_LOCAL);

        PWMGenEnable(PWM0_BASE, PWM_GEN_2);

    Thanks, Doug

  • 0 in reply to Doug Broadwell85
    TI__Guru**** 184426 points

    Hi Doug,

      PF2 pin which outputs PWM2 is controlled by PWM_GEN_1, not PWM_GEN_2 as I see in your code. 

  • 0 in reply to Charles Tsai
    Intellectual 440 points

    Thanks again Charles, I had misunderstood the structure of the PWM.

    Doug