efm32g210f128_uart_example_01.c

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

#include "em_device.h"
#include "em_chip.h"
#include "em_usart.h"
#include "em_cmu.h"
#include "em_emu.h"


static uint32_t system_count = 0;
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_usart1(void);
void init_portio(void);

__STATIC_INLINE void uart1_putstr(uint8_t* buffer, size_t length);

char txbuffer[128];
#define printf(...) do { \
        sprintf(txbuffer, __VA_ARGS__); \
        uart1_putstr((uint8_t*)txbuffer, strlen(txbuffer)); \
    } while (0)

#define putch(CH) USART_Tx(USART1, CH)

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

    /* Enter default mode: prepare all...  */
    init_clocks();
    init_usart1();
    init_portio();

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

    /* Start Systick Timer */
    setup_systick_timer();   

    reset_blink(30);    

    /* Infinite loop */
    while (1) {
        GPIO_PinOutClear(gpioPortA, 0);
        __delay_ms(10);
        GPIO_PinOutSet(gpioPortA, 0);

        printf("count = %u\r\n", system_count++);        
        __delay_ms(1000 - (get_systick() % 1000));
    }
}


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)
{
    while (countdown--) {
        GPIO_PinOutToggle(gpioPortA, 0);
        __delay_ms(20);
    }
}


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 USART1 */
    CMU_ClockEnable(cmuClock_USART1, true);

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

    // [Peripheral Clock enables]$
}



void init_usart1(void)
{
    // $[USART_InitAsync]
    USART_InitAsync_TypeDef initasync = USART_INITASYNC_DEFAULT;

    initasync.baudrate = 115200;
    initasync.databits = usartDatabits8;
    initasync.parity = usartNoParity;
    initasync.stopbits = usartStopbits1;
    initasync.oversampling = usartOVS16;
#if defined( USART_INPUT_RXPRS ) && defined( USART_CTRL_MVDIS )
    initasync.mvdis = 0;
    initasync.prsRxEnable = 0;
    initasync.prsRxCh = 0;
#endif

    USART_InitAsync(USART1, &initasync);
    // [USART_InitAsync]$

    // $[USART_InitPrsTrigger]
    USART_PrsTriggerInit_TypeDef initprs = USART_INITPRSTRIGGER_DEFAULT;

    initprs.rxTriggerEnable = 0;
    initprs.txTriggerEnable = 0;
    initprs.prsTriggerChannel = usartPrsTriggerCh0;

    USART_InitPrsTrigger(USART1, &initprs);
    // [USART_InitPrsTrigger]$

}



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 PA1 is configured to Input enabled with pull-up */
    GPIO->P[0].DOUT |= (1 << 1);
    GPIO->P[0].MODEL = (GPIO->P[0].MODEL & ~_GPIO_P_MODEL_MODE1_MASK)
            | GPIO_P_MODEL_MODE1_INPUTPULL;
    // [Port A Configuration]$

    // $[Port C Configuration]

    /* Pin PC0 is configured to Push-pull */
    GPIO->P[2].MODEL = (GPIO->P[2].MODEL & ~_GPIO_P_MODEL_MODE0_MASK)
            | GPIO_P_MODEL_MODE0_PUSHPULL;

    /* Pin PC1 is configured to Input enabled */
    GPIO->P[2].MODEL = (GPIO->P[2].MODEL & ~_GPIO_P_MODEL_MODE1_MASK)
            | GPIO_P_MODEL_MODE1_INPUT;
    // [Port C Configuration]$


    // $[Route Configuration]
    /* Enable signals RX, TX */
    USART1->ROUTE |= USART_ROUTE_RXPEN | USART_ROUTE_TXPEN;
    // [Route Configuration]$
}


__STATIC_INLINE void uart1_putstr(uint8_t* buffer, size_t length)
{
    while (length--) {
        putch(*buffer++);
    }
}