/*
 * This program drives the speaker on the Wytec EduBase board
 * at 440 Hz using WTIMER0A in PWM mode.
 *
 */

#include "TM4C123GH6PM.h"

void delayMs(int n);
void delayUs(int n);

int main(void)
{
    SYSCTL->RCGCGPIO |= 0x04;       // enable clock to GPIOC
    SYSCTL->RCGCWTIMER |= 0x01;     // enable clock to Timer Block 0

    // enable PORTC 4 as output
    GPIOC->AMSEL &= ~0x10;          // disable analog function of PORTC 4
    GPIOC->DIR |= 0x10;             // set PORTC 4 as output pins
    GPIOC->DEN |= 0x10;             // set PORTC 4 as digital pins
    GPIOC->AFSEL |= 0x10;           // enable alternate function
    GPIOC->PCTL &= ~0x000F0000;     // clear alternate function for PORTC 4
    GPIOC->PCTL |=  0x00070000;     // set PORTC 4 alternate function to WTIMER
    
    WTIMER0->CTL &= ~1;             // disable WTIMER0A during setup
    WTIMER0->CFG = 4;               // configure as 32-bit timer mode
    WTIMER0->TAMR = 0x0A;           // down-count, PWM-periodic mode
    WTIMER0->TAILR = 36362;         // set frequency to 440 Hz
    WTIMER0->TAMATCHR = 18180;      // set duty cycle to 50%
    WTIMER0->CTL |= 1;              // enable WTIMER0A

    while(1)
    {
    }
}

// delay n milliseconds (16 MHz CPU clock)
void delayMs(int n)
{
    int i, j;
    for(i = 0 ; i < n; i++)
        for(j = 0; j < 3180; j++)
            {}  // do nothing for 1 ms
}

// delay n microseconds (16 MHz CPU clock)
void delayUs(int n)
{
    int i, j;
    for(i = 0 ; i < n; i++)
        for(j = 0; j < 3; j++)
            {}  // do nothing for 1 us
}

// This function is called by the startup assembly
// code to perform system specific initialization tasks.
void SystemInit(void)
{
    // Grant coprocessor access
    // This is required since TM4C123G has
    // a floating point coprocessor
    SCB->CPACR |= 0x00f00000;
}