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FTM PWM setup problem

Question asked by Roger Clark on Jun 5, 2019
Latest reply on Jun 6, 2019 by Roger Clark

I have a problem setting up PWM on MK22


The device has a backlight LED on an LCD display, which is on PORTC pin 4


Simple GPIO works fine, but I cant seem to get PWM working


Using the SDK example as a template, I've set the port/pin as


    PORT_SetPinMux(PORTC,4, kPORT_MuxAlt4);/* Configured as PWM FTM0_CH4 */


But I'm not sure if kPOST_MuxAlt4 is OK for Port C, since the example LED pin was on Port D


I've setup the FTM as per the template, except I'm only using 1kHz instead of 24kHz


    ftm_config_t ftmInfo;
    ftm_chnl_pwm_signal_param_t ftmParam;
    ftmParam.chnlNumber = BOARD_FTM_CHANNEL;
    ftmParam.level = kFTM_LowTrue;
    ftmParam.dutyCyclePercent = 99;
    ftmParam.firstEdgeDelayPercent = 0U;


    FTM_Init(BOARD_FTM_BASEADDR, &ftmInfo);/* Initialize FTM module */
    FTM_SetupPwm(BOARD_FTM_BASEADDR, &ftmParam, 1U, kFTM_CenterAlignedPwm, 1000U, FTM_SOURCE_CLOCK);

    FTM_StartTimer(BOARD_FTM_BASEADDR, kFTM_SystemClock);



But I don't seem to be getting any PWM from the pin.


I also tried setting the pin as output


GPIO_PinInit(PORTC, 4, &pin_config_output);


But that didn't resolve the problem.


So I don't know what I've missed or have done wrong.