main.c

/*################################################
# Hardware PWM proof of concept using
# the Tiva C Launchpad
#
# Started with example code by
# lawrence_jeff found here:
# http://forum.stellarisiti.com/topic/707-using-hardware-pwm-on-tiva-launchpad/
# 
# Altered to use code found on section
# 22.3 of the TivaWare Peripheral Driver
# Library User's Guide found here:
# http://www.ti.com/lit/ug/spmu298a/spmu298a.pdf
#
#
# This example pulses three on-board LEDs
#
#################################################*/


#include "driverlib/pin_map.h"
#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_gpio.h"
#include "inc/hw_types.h"
#include "inc/hw_memmap.h"
#include "driverlib/sysctl.h"
#include "driverlib/pin_map.h"
#include "driverlib/gpio.h"
#include "driverlib/pwm.h"

void delayMS(int ms) {
    SysCtlDelay( (SysCtlClockGet()/(3*1000))*ms ) ;
}

int
main(void)
{
    //Set the clock
   SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC |   SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);

   //Configure PWM Clock to match system
   SysCtlPWMClockSet(SYSCTL_PWMDIV_1);

   // Enable the peripherals used by this program.
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM1);  //The Tiva Launchpad has two modules (0 and 1). Module 1 covers the LED pins

    //Configure PF1,PF2,PF3 Pins as PWM
    GPIOPinConfigure(GPIO_PF1_M1PWM5);
    GPIOPinConfigure(GPIO_PF2_M1PWM6);
    GPIOPinConfigure(GPIO_PF3_M1PWM7);
    GPIOPinTypePWM(GPIO_PORTF_BASE, GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3);

    //Configure PWM Options
    //PWM_GEN_2 Covers M1PWM4 and M1PWM5
    //PWM_GEN_3 Covers M1PWM6 and M1PWM7 See page 207 4/11/13 DriverLib doc
    PWMGenConfigure(PWM1_BASE, PWM_GEN_2, PWM_GEN_MODE_DOWN | PWM_GEN_MODE_NO_SYNC); 
    PWMGenConfigure(PWM1_BASE, PWM_GEN_3, PWM_GEN_MODE_DOWN | PWM_GEN_MODE_NO_SYNC); 

    //Set the Period (expressed in clock ticks)
    PWMGenPeriodSet(PWM1_BASE, PWM_GEN_2, 320);
    PWMGenPeriodSet(PWM1_BASE, PWM_GEN_3, 320);

    //Set PWM duty-50% (Period /2)
    PWMPulseWidthSet(PWM1_BASE, PWM_OUT_5,100);
    PWMPulseWidthSet(PWM1_BASE, PWM_OUT_6,100);
    PWMPulseWidthSet(PWM1_BASE, PWM_OUT_7,100);

    // Enable the PWM generator
    PWMGenEnable(PWM1_BASE, PWM_GEN_2);
    PWMGenEnable(PWM1_BASE, PWM_GEN_3);

    // Turn on the Output pins
    PWMOutputState(PWM1_BASE, PWM_OUT_5_BIT | PWM_OUT_6_BIT | PWM_OUT_7_BIT, true);

    //Fade
    bool fadeUp = true;
    unsigned long increment = 10;
    unsigned long pwmNow = 100;
    while(1)
    {
        delayMS(20);
        if (fadeUp) {
            pwmNow += increment;
            if (pwmNow >= 320) { fadeUp = false; }
        }
        else {
            pwmNow -= increment;
            if (pwmNow <= 10) { fadeUp = true; }
        }
        PWMPulseWidthSet(PWM1_BASE, PWM_OUT_5,pwmNow);
        PWMPulseWidthSet(PWM1_BASE, PWM_OUT_6,pwmNow);
        PWMPulseWidthSet(PWM1_BASE, PWM_OUT_7,pwmNow);
    }

}