FreeRTOS学习笔记——二值型信号量

/* Standard includes. */
#include <stdio.h>
#include <string.h>

/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "semphr.h"

/* Library includes. */
#include "stm32f10x.h"

#define LED0_ON()   GPIO_SetBits(GPIOB,GPIO_Pin_5);
#define LED0_OFF()  GPIO_ResetBits(GPIOB,GPIO_Pin_5);

static void Setup(void);
static void PrintTask(void *pvParameters);

void LedInit(void);
void UART1Init(void);

uint8_t RxBuffer[128];
__IO uint8_t RxCounter = 0;

SemaphoreHandle_t xSemaphore;

int main(void)
{
    /* 初始化硬件平台 */
    Setup();
    
    /* 创建信号量 */
    xSemaphore = xSemaphoreCreateBinary();
    /* 建立Print任务 */
    xTaskCreate(PrintTask, "Print Task", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY+4, NULL);
    /* 启动OS */
    vTaskStartScheduler();
    
    return 0;
}

void PrintTask(void *pvParameters)
{
    for(;;)
    {
        if( xSemaphoreTake( xSemaphore, portMAX_DELAY ) == pdTRUE )
        {
            printf("receive:%s", RxBuffer);
            memset(RxBuffer, 0x00, 128);
            RxCounter = 0;
        }
    }
}

static void Setup( void )
{
    LedInit();
    UART1Init();
}

void LedInit( void )
{
    GPIO_InitTypeDef GPIO_InitStructure;
    RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOB, ENABLE );
    /*LED0 @ GPIOB.5*/
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_Init( GPIOB, &GPIO_InitStructure );    
}

void UART1Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    
    /* 第1步：打开GPIO和USART时钟 */
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_USART1, ENABLE);
    
    /* 第2步：将USART1 Tx@PA9的GPIO配置为推挽复用模式 */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    
    /* 第3步：将USART1 Rx@PA10的GPIO配置为浮空输入模式 */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    
    /* 第4步：配置USART1参数
    波特率   = 9600
    数据长度 = 8
    停止位   = 1
    校验位   = No
    禁止硬件流控(即禁止RTS和CTS)
    使能接收和发送
    */
    USART_InitStructure.USART_BaudRate = 9600;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART1, &USART_InitStructure);
    
    /* 第5步：使能 USART1， 配置完毕 */
    USART_Cmd(USART1, ENABLE);
    
    /* 清除发送完成标志 */
    USART_ClearFlag(USART1, USART_FLAG_TC);
    
    /* 使能USART1发送中断和接收中断，并设置优先级 */
    NVIC_InitTypeDef NVIC_InitStructure;
    /* 设定USART1 中断优先级 */
    NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = configLIBRARY_KERNEL_INTERRUPT_PRIORITY; 
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
    /* 使能接收中断 */
    USART_ITConfig(USART1, USART_IT_RXNE, ENABLE); 
}

int fputc(int ch, FILE *f)
{
    /* 写一个字节到USART1 */
    USART_SendData(USART1, (uint8_t) ch);
    /* 等待发送结束 */
    while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET)
    {}
    return ch;
}

void USART1_IRQHandler(void)
{
    static BaseType_t xHigherPriorityTaskWoken;
    
    if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)
    {
        RxBuffer[RxCounter++] = USART_ReceiveData(USART1);
        if (RxCounter > 2 && RxBuffer[RxCounter-2] == ‘\r‘ && RxBuffer[RxCounter-1] == ‘\n‘) {
            // 在中断中发送信号量
            xSemaphoreGiveFromISR( xSemaphore, &xHigherPriorityTaskWoken );
        }
    }
    
    portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
}

#define vSemaphoreCreateBinary( xSemaphore )     {         ( xSemaphore ) = xQueueGenericCreate( ( unsigned portBASE_TYPE ) 1, semSEMAPHORE_QUEUE_ITEM_LENGTH, queueQUEUE_TYPE_BINARY_SEMAPHORE );         if( ( xSemaphore ) != NULL )         {             ( void ) xSemaphoreGive( ( xSemaphore ) );         }     }