/* p11_5.c Comparison between Single-slope and Dual-slope PWM
 *
 * TCC1 is configured for single-slope PWM as reference.
 * TCC0 is configured for dual-slope PWM. See text for
 * detailed comparison.
 *
 * TCC0 output - PA08, TCC1 output - PA10
 *
 * Tested with Atmel Studio 7 v7.0.1006 and Keil MDK-ARM v5.21a.
 */

#include "samd21.h"

void TCC0_init(void);
void TCC1_init(void);

unsigned char* ARRAY_PORT_PINCFG0 = (unsigned char*)&REG_PORT_PINCFG0;
unsigned char* ARRAY_PORT_PMUX0 = (unsigned char*)&REG_PORT_PMUX0;

int main(void) {
    TCC0_init();
    TCC1_init();
    
    while (1) {
    }
}

/* TCC0 is used to generate dual-slope PWM.
 * The output is 100 Hz.
 * PA08 is used as output pin.
 */
void TCC0_init(void) {
    REG_GCLK_CLKCTRL = 0x401A;      /* GCLK0 -> TCC0, TCC1 */
    REG_PM_APBCMASK |= 0x00000100;  /* enable TCC0 Clock in PM */
    REG_TCC0_CTRLA = 1;             /* reset */
    while (REG_TCC0_CTRLA & 1) {}   /* wait till out of reset */
    REG_TCC0_WAVE = 7;              /* dual-slope TOP PWM */
    REG_TCC0_PER = 5000;            /* period */
    REG_TCC0_CC0 = 1500;            /* pulse width */
    REG_TCC0_CTRLA |= 2;            /* enable */

    ARRAY_PORT_PINCFG0[8] |= 1;     /* make PA08 output for TCC0 */
    ARRAY_PORT_PMUX0[4] = 0x04;     /* PA08 = TCC0 */
}

/* TCC1 is used to generate single-slope PWM.
 * The output is 200 Hz.
 * PA10 is used as output pin.
 */
void TCC1_init(void) {
    REG_GCLK_CLKCTRL = 0x401A;      /* GCLK0 -> TCC0, TCC1 */
    REG_PM_APBCMASK |= 0x00000200;  /* enable TCC1 Clock in PM */
    REG_TCC1_CTRLA = 1;             /* reset */
    while (REG_TCC1_CTRLA & 1) {}   /* wait till out of reset */
    REG_TCC1_WAVE = 2;              /* Normal PWM */
    REG_TCC1_PER = 5000 - 1;        /* period */
    REG_TCC1_CC0 = 1500 - 1;        /* pulse width */
    REG_TCC1_CTRLA |= 2;            /* enable */

    ARRAY_PORT_PINCFG0[10] |= 1;    /* make PA10 output for TCC1 */
    ARRAY_PORT_PMUX0[5] = 0x04;     /* PA10 = TCC1 */
}