pwm.cpp

#include <Arduino.h>
#include "pwm.h"
#include "config.h"

void setup_pwm()
{
    pinMode(42, OUTPUT);

    pmc_enable_periph_clk (PWM_INTERFACE_ID) ;  // turn on clocking to PWM unit

    PWMC_DisableChannel(PWM_INTERFACE, 0);
    PWMC_DisableChannel(PWM_INTERFACE, 1);
    PWMC_DisableChannel(PWM_INTERFACE, 2);

    // Configure (PC2) through (PC7) to be PWM now. This causes all of them to be PWM channels 0, 1, 2
    PIOC->PIO_PDR = 0xFC;  // disable PIO control for all of them
    PIOC->PIO_IDR = 0xFC;   // disable PIO interrupts for all of them
    PIOC->PIO_ABSR |= 0xFC;  // switch to B peripheral

    //assuming 10khz and 1050 that would be a clock of 21MHz (Center aligned is twice speed)
    //Center aligned mode counts from 0 up to max then back down to 0 every cycle
    //so you need twice the frequency to get the same result as left aligned mode.
    PWMC_ConfigureClocks((unsigned int)PWM_FREQ * MAX_PWM_DUTY * 2, 0, VARIANT_MCK );

    //                   PWM, Chan, Clock, Left/Center, Polarity, CountEvent, DeadEnable, DeadHighInv, DeadLowInv
    //PWM_CMR_DTHI PWM_CMR_DTLI, PWM_CMR_CPOL
    PWMC_ConfigureChannelExt (PWM, 0, PWM_CMR_CPRE_CLKA, PWM_CMR_CALG, 0, 0, PWM_CMR_DTE, 0, 0);
    PWMC_SetPeriod (PWM_INTERFACE, 0, MAX_PWM_DUTY) ;  // period = 525 ticks (10Khz), every tick is 1/5.25 micro seconds
    PWMC_SetDutyCycle (PWM_INTERFACE, 0, 0); //set duty cycle of channel 0 to 0 (duty is out of the period above so min is 0 max is 1050)
    PWMC_SetDeadTime(PWM_INTERFACE, 0, PWM_DEADTIME, PWM_DEADTIME) ; //set a bit of dead time around all transitions

    PWMC_ConfigureChannelExt (PWM, 1, PWM_CMR_CPRE_CLKA, PWM_CMR_CALG, 0, 0, PWM_CMR_DTE, 0, 0);
    PWMC_SetPeriod (PWM, 1, MAX_PWM_DUTY) ;
    PWMC_SetDutyCycle (PWM, 1, 0); //set duty cycle of channel 0 to 0 (duty is out of the period above
    PWMC_SetDeadTime(PWM, 1, PWM_DEADTIME, PWM_DEADTIME) ; //set some dead time

    PWMC_ConfigureChannelExt (PWM, 2, PWM_CMR_CPRE_CLKA, PWM_CMR_CALG, 0, 0, PWM_CMR_DTE, 0, 0);
    PWMC_SetPeriod (PWM, 2, MAX_PWM_DUTY) ;
    PWMC_SetDutyCycle (PWM, 2, 0); //set duty cycle of channel 0 to 0 (duty is out of the period above
    PWMC_SetDeadTime(PWM, 2, PWM_DEADTIME, PWM_DEADTIME) ; //set some dead time

    PWMC_ConfigureSyncChannel(PWM_INTERFACE, 7, 0, 0,0); //make channels 0, 1, 2 be synchronous
    PWMC_SetSyncChannelUpdatePeriod(PWM_INTERFACE, 1);
    PWMC_ConfigureChannelExt(PWM_INTERFACE, 0, PWM_CMR_CPRE_CLKA, PWM_CMR_CALG, 0, 0, PWM_CMR_DTE, 0, 0);
    PWMC_ConfigureChannelExt(PWM_INTERFACE, 1, PWM_CMR_CPRE_CLKA, PWM_CMR_CALG, 0, 0, PWM_CMR_DTE, 0, 0);
    PWMC_ConfigureChannelExt(PWM_INTERFACE, 2, PWM_CMR_CPRE_CLKA, PWM_CMR_CALG, 0, 0, PWM_CMR_DTE, 0, 0);

    //Configure PWM hardware comparison unit to trigger while counting up and at the max duty value
    int compMode = PWM_CMPM_CEN; //+ PWM_CMPM_CTR(0) + PWM_CMPM_CPR(0) + PWM_CMPM_CUPR(0);
    PWMC_ConfigureComparisonUnit(PWM_INTERFACE, 0, MAX_PWM_DUTY, compMode);
    //Use comparison unit 0 for Event line 0 which the ADC hardware is looking for triggers on
    PWMC_ConfigureEventLineMode(PWM_INTERFACE, 0, PWM_ELMR_CSEL0);

    /*
      PWM->PWM_FMR = (1 << 4); //set FPOL for ADC fault input to 1
      delayMicroseconds(50);
      PWM->PWM_FMR |= (1 << 12); //then set mode to require manual clearing of ADC fault
      delayMicroseconds(50);
      PWM->PWM_FPE1 = (1 << 4); //all three channels are synch. so they all use Chan 0
      delayMicroseconds(50);
      */
    PWMC_EnableChannel (PWM_INTERFACE, 0) ;   // enable
    PWMC_EnableChannel (PWM_INTERFACE, 1) ;   // enable
    PWMC_EnableChannel (PWM_INTERFACE, 2) ;   // enable
}

void updatePWM(unsigned int a, unsigned int b, unsigned int c)
{
    static int ledCounter = 0;
    int pwmBuff = PWM_BUFFER;
    uint32_t upperDuty = MAX_PWM_DUTY - pwmBuff;
    uint32_t dutyA = a, dutyB = b, dutyC = c;

    //For debugging purposes the LED flashes in time to the PWM frequency. If the LED is flashing you're still up and running.
    ledCounter++;
    if (ledCounter == 1000) PIO_SetOutput(PIOC, PIO_PC20, HIGH, 0, PIO_PULLUP);
    if (ledCounter == 2000)
    {
        PIO_SetOutput(PIOC, PIO_PC20, LOW, 0, PIO_PULLUP);
        ledCounter = 0;
    }

    //Prevent both types of short pulses.
    if (dutyA < PWM_BUFFER) dutyA = 0;
    if (dutyB < PWM_BUFFER) dutyB = 0;
    if (dutyC < PWM_BUFFER) dutyC = 0;

    if (dutyA > upperDuty) dutyA = MAX_PWM_DUTY;
    if (dutyB > upperDuty) dutyB = MAX_PWM_DUTY;
    if (dutyC > upperDuty) dutyC = MAX_PWM_DUTY;

    PWMC_SetDutyCycle (PWM_INTERFACE, 0, dutyA);
    PWMC_SetDutyCycle (PWM_INTERFACE, 1, dutyB);
    PWMC_SetDutyCycle (PWM_INTERFACE, 2, dutyC);
    PWMC_SetSyncChannelUpdateUnlock(PWM_INTERFACE); //enable setting of all those duties all at once
}