EFM32片内外设--LEUart高波特率测试

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我是靠谱客的博主顺心店员，最近开发中收集的这篇文章主要介绍EFM32片内外设--LEUart高波特率测试，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

虽然心里一认为LEUart如果使用二分之一的Core clock的话，是可以支持高波特率的。但是一直没有做过测试。呵呵。心里也没底哈。

利用原先的那个demo，将LEUart的时钟源配置为二分之一的core clock，重新测试了一边。证明LEUart是可以工作于高波特率的。

但是注意的是，LEUart的分频系数整数部分为7位，因此最大分频系数为128，如果波特率如果太小的话，反而实现不了了哦。呵呵。否则将core clock预分频。呵呵。

硬件准备： TG STK， LEUart0， Tx：PD4， Rx：PD5. TG STK的20pin扩展口上已经有这两个IO口，分别是12Pin（PD4,Tx），14Pin（PD5,Rx）。

代码:

#include <stdint.h>
#include <stdbool.h>
#include "efm32.h"
#include "em_chip.h"
#include "em_cmu.h"
#include "em_leuart.h"
#include "em_gpio.h"

unsigned char ucString[] = {
"Hello world,This is a test for LEUart from Gecko.rn"
};

#define LINK_UART_TX_PORT           gpioPortD
#define LINK_UART_TX_BIT            4
#define LINK_UART_TX_MODE           gpioModePushPull

#define LINK_UART_RX_PORT           gpioPortD
#define LINK_UART_RX_BIT            5
#define LINK_UART_RX_MODE           gpioModeInputPull

#define LINK_CMU_UART               cmuClock_LEUART0
#define LINK_UART                   LEUART0
#define LINK_UART_ROUTE_EN          LEUART_ROUTE_TXPEN | LEUART_ROUTE_RXPEN
#define LINK_UART_ROUTE_LOCATION    LEUART_ROUTE_LOCATION_LOC0

#define LINK_REF_FREQUENCY CMU_ClockFreqGet(LINK_CMU_UART)

#define LINK_UART_IRQ LEUART0_IRQn

#define LEUART_STATUS LEUART0->STATUS
#define UARTTXC 0x08

void LEUart_Init(void)
{
    CMU_ClockEnable(cmuClock_HFPER, true);
    CMU_ClockEnable(cmuClock_GPIO, true);
    CMU_ClockEnable(cmuClock_CORELE, true);

    CMU_ClockSelectSet(cmuClock_LFB, cmuSelect_CORELEDIV2);
    CMU_ClockEnable(cmuClock_LEUART0, true);

    /* Defining the LEUART1 initialization data */
    LEUART_Init_TypeDef leuart1Init =
    {
        .enable   = leuartEnable,         /* Activate data reception on LEUn_TX pin. */
        .refFreq = LINK_REF_FREQUENCY,   /* Inherit the clock frequenzy from the LEUART clock source */
        .baudrate = 230400,                 /* Baudrate */
        .databits = leuartDatabits8,      /* Each LEUART frame containes 8 databits */
        .parity   = leuartNoParity,       /* No parity bits in use */
        .stopbits = leuartStopbits1,      /* Setting the number of stop bits in a frame to 2 bitperiods */
    };

    LEUART_Init_TypeDef Leuart_Init = leuart1Init;

    /* Reseting and initializing LEUART1 */
    LEUART_Reset(LINK_UART);

    /* Route LEUART1 TX pin to DMA location 0 */
    LINK_UART->ROUTE = LINK_UART_ROUTE_EN | LINK_UART_ROUTE_LOCATION;

    LEUART_Init(LINK_UART, &Leuart_Init);

    //LEUART_IntEnable(LINK_UART, LEUART_IEN_RXDATAV);

    //NVIC_SetPriority(LINK_UART_IRQ,7);
    /* Enable LEUART1 interrupt vector */
    //NVIC_EnableIRQ(LINK_UART_IRQ);

    /* Enable GPIO for LEUART0. */
    GPIO_PinModeSet(LINK_UART_TX_PORT, LINK_UART_TX_BIT, LINK_UART_TX_MODE, 1);
    GPIO_PinModeSet(LINK_UART_RX_PORT, LINK_UART_RX_BIT, LINK_UART_RX_MODE, 1);
}

/**************************************************************************//**
* @brief Main function
*****************************************************************************/
int main(void)
{
    /* Chip errata */
    CHIP_Init();
    /* Turning on HFXO to increase frequency accuracy. */
    /* Waiting until oscillator is stable */
    CMU->OSCENCMD = CMU_OSCENCMD_HFXOEN;
    while (!(CMU->STATUS && CMU_STATUS_HFXORDY)) ;

    /* Switching the CPU clock source to HFXO */
    CMU->CMD = CMU_CMD_HFCLKSEL_HFXO;

    LEUart_Init();

    while(1)
    {
        unsigned long ulDelay = 1000000;
        while(ulDelay--);
        for(unsigned char i = 0; i < 53; i++)
        {
            LEUART_Tx(LINK_UART, ucString[i]);
        }
    }
}