FRDM-K22F gpio and ftm peripheral drivers

[jimmynguyen]

Hello all,

I am currently using KDS v3.0 and KSDK v1.3 to program the FRDM-K22F.  I am trying to output a PWM using the FTM driver into a GPIO pin on the board so that I am able to drive a the step frequency of a motor.  I took a look at the FTM driver and GPIO driver example, I am a little confused with how to set up the a GPIO pin for FTM usage.  

Thankyou,

Jimmy

[jorge_a_vazquez · Accepted solution]

Hi Jimmy Nguyen

You don't need look into GPIO example to implement an output of PWM using the FTM, FTM channel can be configured for edge-aligned PWM mode, and the signal will be in the pin associated. For example, the SDK 1.3 FTM example uses the FTM0_CH5 witch is in PTD5 (LED) as ATL4:

So inside the hardware_init() you can find the ftm pin configuration with:

 PORT_HAL_SetMuxMode(PORTD,5u,kPortMuxAlt4);‍‍‍

The example code set a PWM with a frequency of 24kHZ and a initial duty cycle of 0 that will be increasing and decreasing in the while(1), so you will see changes in the LED brightness:

    ftm_pwm_param_t ftmParam = {
        .mode                   = kFtmEdgeAlignedPWM,
        .edgeMode               = kFtmLowTrue,
        .uFrequencyHZ           = 24000u,
        .uDutyCyclePercent      = 0,
        .uFirstEdgeDelayPercent = 0,
    };‍‍‍‍‍‍‍‍‍‍‍‍‍‍

 if(brightnessUp)
        {
            // Increase duty cycle until it reach limited value
            if (++ftmParam.uDutyCyclePercent == 100u)
                brightnessUp = false;
        }
        else
        {
            // Decrease duty cycle until it reach limited value.
            if (--ftmParam.uDutyCyclePercent == 0)
                brightnessUp = true;
        }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Hope this information helps you
Have a great day,
Jorge Alcala

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