efm32g210f128_timer0_pwm_example.c

#include <stdio.h>
#include <string.h>
#include <inttypes.h>

#include "em_device.h"
#include "em_chip.h"
#include "em_cmu.h"
#include "em_emu.h"
#include "em_int.h"
#include "em_timer.h"

#define LED_PIN             (0)
#define LED_PORT            (gpioPortA)


volatile uint32_t systick_count = 0;
uint32_t clock_freq;

__STATIC_INLINE void __delay_tick(volatile uint32_t n);
__STATIC_INLINE uint32_t get_systick(void);
void __delay_ms(uint32_t milliseconds);
void setup_systick_timer(void);
void reset_blink(volatile uint8_t countdown);

void init_clocks(void);
void init_timer0(void);
void init_portio(void);

/* Define PWM frequency value */
#define PWM_FREQ 20000

uint32_t timer0_top;


void pulse_out(unsigned int ch, uint32_t duty_cycle)
{
    if (duty_cycle <= 100)
        TIMER_CompareBufSet(TIMER0, ch, (duty_cycle * timer0_top) / 100);
}


/**************************************************************************//**
 * @brief  Main function
 *****************************************************************************/
int main(void)
{
    /* Chip errata */
    CHIP_Init();

    /* Enter default mode */
    init_clocks();
    init_portio();    
    init_timer0();

    /* Ensure core frequency has been updated */
    SystemCoreClockUpdate();

    /* Start Systick Timer */
    setup_systick_timer();    

    /* Set Top Value */
    uint32_t freq = CMU_ClockFreqGet(cmuClock_HFPER);
    timer0_top = freq / PWM_FREQ;
    TIMER_TopSet(TIMER0, timer0_top);

    reset_blink(30);

    /* Infinite loop */
    while (1) {
        for (uint32_t i = 0; i <= 100; i++) {
            pulse_out(0, i);
            pulse_out(2, 100 - i);
            __delay_ms(15);
        }
    }
}


void SysTick_Handler(void)
{
    systick_count++;
}

__STATIC_INLINE uint32_t get_systick(void)
{
    return systick_count;
}

/******************************************************************************
 * @brief Delay function
 *****************************************************************************/
void __delay_ms(uint32_t milliseconds)
{
    uint32_t start_tick = get_systick();
    while ((get_systick() - start_tick) < milliseconds) {
    }
}


void setup_systick_timer(void)
{
    clock_freq = CMU_ClockFreqGet(cmuClock_CORE);
    /* Enable SysTick interrupt, necessary for __delay_ms() */
    if (SysTick_Config(CMU_ClockFreqGet(cmuClock_CORE) / 1000)) while (1) ;
    NVIC_EnableIRQ(SysTick_IRQn);
}


void reset_blink(volatile uint8_t countdown)
{
    volatile uint8_t cnt = countdown / 2;
    while (cnt--) {
        pulse_out(0, 100);
        __delay_ms(20);
        pulse_out(0, 0);
        __delay_ms(20);
    }
    __delay_ms(1000);
}


void init_clocks(void)
{
    // $[HFXO]
    CMU->CTRL = (CMU->CTRL & ~_CMU_CTRL_HFXOMODE_MASK) | CMU_CTRL_HFXOMODE_XTAL;

    CMU->CTRL = (CMU->CTRL & ~_CMU_CTRL_HFXOBOOST_MASK)
            | CMU_CTRL_HFXOBOOST_50PCENT;

    SystemHFXOClockSet(32000000);

    // $[Use oscillator source]
    CMU->CTRL = (CMU->CTRL & ~_CMU_CTRL_LFXOMODE_MASK) | CMU_CTRL_LFXOMODE_XTAL;
    // [Use oscillator source]$

    // $[LFXO Boost Percent]
    CMU->CTRL = (CMU->CTRL & ~_CMU_CTRL_LFXOBOOST_MASK)
            | CMU_CTRL_LFXOBOOST_100PCENT;
    // [LFXO Boost Percent]$

    // $[LFXO enable]
    CMU_OscillatorEnable(cmuOsc_LFXO, true, true);
    // [LFXO enable]$

    // $[HFXO enable]
    CMU_OscillatorEnable(cmuOsc_HFXO, true, true);
    // [HFXO enable]$

    // $[High Frequency Clock select]
    /* Using HFXO as high frequency clock, HFCLK */
    CMU_ClockSelectSet(cmuClock_HF, cmuSelect_HFXO);

    /* Enable peripheral clock */
    CMU_ClockEnable(cmuClock_HFPER, true);

    // [High Frequency Clock select]$

    // $[Peripheral Clock enables]
    /* Enable clock for TIMER0 */
    CMU_ClockEnable(cmuClock_TIMER0, true);

    /* Enable clock for GPIO by default */
    CMU_ClockEnable(cmuClock_GPIO, true);

    // [Peripheral Clock enables]$
}


void init_portio(void)
{
    // $[Port A Configuration]
    /* Pin PA0 is configured to Push-pull */
    GPIO->P[0].MODEL = (GPIO->P[0].MODEL & ~_GPIO_P_MODEL_MODE0_MASK)
            | GPIO_P_MODEL_MODE0_PUSHPULL;

    /* Pin PA2 is configured to Push-pull */
    GPIO->P[0].MODEL = (GPIO->P[0].MODEL & ~_GPIO_P_MODEL_MODE2_MASK)
            | GPIO_P_MODEL_MODE2_PUSHPULL;
    // [Port A Configuration]$

    // $[Route Configuration]
    /* Enable signals CC0, CC2 */
    TIMER0->ROUTE |= TIMER_ROUTE_CC0PEN | TIMER_ROUTE_CC2PEN;
    // [Route Configuration]$
}


void init_timer0(void)
{
    // $[TIMER0 initialization]
    TIMER_Init_TypeDef init = TIMER_INIT_DEFAULT;

    init.enable = 1;
    init.debugRun = 1;
    init.dmaClrAct = 0;
    init.sync = 0;
    init.clkSel = timerClkSelHFPerClk;
    init.prescale = timerPrescale64;
    init.fallAction = timerInputActionNone;
    init.riseAction = timerInputActionNone;
    init.mode = timerModeUp;
    init.quadModeX4 = 0;
    init.oneShot = 0;
    TIMER_Init(TIMER0, &init);
    // [TIMER0 initialization]$

    // $[TIMER0 CC0 init]
    TIMER_InitCC_TypeDef initCC0 = TIMER_INITCC_DEFAULT;

    initCC0.prsInput = false;
    initCC0.prsSel = timerPRSSELCh0;
    initCC0.edge = timerEdgeBoth;
    initCC0.mode = timerCCModePWM;
    initCC0.eventCtrl = timerEventEveryEdge;
    initCC0.filter = 0;
    initCC0.cofoa = timerOutputActionNone;
    initCC0.cufoa = timerOutputActionNone;
    initCC0.cmoa = timerOutputActionToggle;
    initCC0.coist = 0;
    initCC0.outInvert = 0;
    TIMER_InitCC(TIMER0, 0, &initCC0);
    // [TIMER0 CC0 init]$

    // $[TIMER0 CC2 init]
    TIMER_InitCC_TypeDef initCC2 = TIMER_INITCC_DEFAULT;

    initCC2.prsInput = false;
    initCC2.prsSel = timerPRSSELCh0;
    initCC2.edge = timerEdgeBoth;
    initCC2.mode = timerCCModePWM;
    initCC2.eventCtrl = timerEventEveryEdge;
    initCC2.filter = 0;
    initCC2.cofoa = timerOutputActionNone;
    initCC2.cufoa = timerOutputActionNone;
    initCC2.cmoa = timerOutputActionToggle;
    initCC2.coist = 0;
    initCC2.outInvert = 0;
    TIMER_InitCC(TIMER0, 2, &initCC2);
    // [TIMER0 CC2 init]$
}