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UART通过DMA接收和发送,使用环形缓冲区,状态机的使用

前言

为了实现UART通过DMA接收和发送不定长度的数据,可以使用环形缓冲区(环形缓冲区)和插入相关的状态机来解析接收到的数据。

步骤

1.启用时钟,配置引脚,配置USART,配置DMA,这些不用说了吧,官方教程有一堆
2.DMA 接收处理,DMA 接收完成中断,这个没什么用,接收到的数据长度不一,DMA只要负责把UART的数据寄存器的数据搬到内存中就行了。
3.UART的接收处理和状态机解析,在UART接收完成中断中,需要处理内存的数据和和状态机解析。
4.UART的发送函数中再初始化txBuffer的DMA,因为每次发送的length不一样。

具体代码

1.初始化 DMA 和 UART:

#define RX_BUFFER_SIZE 1024  // 环形缓冲区大小
#define TX_BUFFER_SIZE 150   // 发送缓冲区大小

uint8_t rxBuffer[RX_BUFFER_SIZE];
uint8_t txBuffer[TX_BUFFER_SIZE];

volatile uint16_t rxWriteIndex = 0;

void UART_DMA_Init(void) {
    USART_InitTypeDef USART_InitStructure;
    DMA_InitTypeDef DMA_InitStructure;
    GPIO_InitTypeDef GPIO_InitStructure;

    // 启用时钟
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);
    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

    // 配置UART引脚
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; // TX
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; // RX
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    // 配置USART
    USART_InitStructure.USART_BaudRate = 115200;
    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_Tx | USART_Mode_Rx;
    USART_Init(USART1, &USART_InitStructure);

    // 配置DMA RX
    DMA_DeInit(DMA1_Channel5);
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&USART1->DR;
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)rxBuffer;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
    DMA_InitStructure.DMA_BufferSize = RX_BUFFER_SIZE;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_Init(DMA1_Channel5, &DMA_InitStructure);

    // 启用DMA
    USART_DMACmd(USART1, USART_DMAReq_Rx, ENABLE);
    DMA_Cmd(DMA1_Channel5, ENABLE);

    // 启用USART
    USART_Cmd(USART1, ENABLE);
}
2.DMA 接收处理和状态机解析:
void DMA1_Channel5_IRQHandler(void) {
    if (DMA_GetITStatus(DMA1_IT_TC5)) {
        DMA_ClearITPendingBit(DMA1_IT_TC5);
        // 传输完成
    }
}

void USART1_IRQHandler(void) {
    if (USART_GetITStatus(USART1, USART_IT_IDLE) != RESET) {
        volatile uint32_t temp;
        temp = USART1->SR;  // 读取USART SR寄存器
        temp = USART1->DR;  // 读取USART DR寄存器以清除IDLE中断标志

        uint16_t rxIndex = RX_BUFFER_SIZE - DMA_GetCurrDataCounter(DMA1_Channel5);

        if (rxIndex != rxWriteIndex) {
            if (rxIndex > rxWriteIndex) {
                ProcessReceivedData(&rxBuffer[rxWriteIndex], rxIndex - rxWriteIndex);
            } else {
                ProcessReceivedData(&rxBuffer[rxWriteIndex], RX_BUFFER_SIZE - rxWriteIndex);
                ProcessReceivedData(&rxBuffer[0], rxIndex);
            }
            rxWriteIndex = rxIndex;
        }
    }
}

void ProcessReceivedData(uint8_t *data, uint16_t length) {
    // 将接收到的数据传入状态机进行解析
    for (uint16_t i = 0; i < length; i++) {
        ParseStateMachine(data[i]);
    }
}

void ParseStateMachine(uint8_t byte) {
    // 根据实际应用编写状态机解析代码
}

3.DMA 发送 UART 数据的代码及发送完处理逻辑
void UART_SendDataDMA(uint8_t *data, uint16_t length) {
    DMA_InitTypeDef DMA_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    // 配置 DMA
    DMA_DeInit(DMA1_Channel4);  // 假设使用 DMA1 Channel4
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&USART1->DR;
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)data;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
    DMA_InitStructure.DMA_BufferSize = length;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

    // 初始化 DMA
    DMA_Init(DMA1_Channel4, &DMA_InitStructure);

    // 清除传输完成标志
    DMA_ClearFlag(DMA1_FLAG_TC4);

    // 配置 NVIC
    NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel4_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    // 使能 DMA传输完成中断
    DMA_ITConfig(DMA1_Channel4, DMA_IT_TC, ENABLE);

    // 使能 DMA 通道
    DMA_Cmd(DMA1_Channel4, ENABLE);

    // 使能 USART 的 DMA 传输请求
    USART_DMACmd(USART1, USART_DMAReq_Tx, ENABLE);
}
// DMA1 Channel4 中断处理
void DMA1_Channel4_IRQHandler(void)
{
    // 检查 DMA 传输完成中断标志
    if (DMA_GetITStatus(DMA1_IT_TC4))
    {
        // 清除传输完成中断标志
        DMA_ClearITPendingBit(DMA1_IT_TC4);

        // 禁用 DMA 通道
        DMA_Cmd(DMA1_Channel4, DISABLE);

        // 其他传输完成后的处理代码...
    }
}
4.主函数调用:
int main(void) {
    UART_DMA_Init();

    // 使能IDLE中断
    USART_ITConfig(USART1, USART_IT_IDLE, ENABLE);
    NVIC_EnableIRQ(USART1_IRQn);
    NVIC_EnableIRQ(DMA1_Channel4_IRQn);
    NVIC_EnableIRQ(DMA1_Channel5_IRQn);

    uint8_t dataToSend[] = "Hello World!";
    UART_SendDataDMA(dataToSend, sizeof(dataToSend) - 1);

    while (1) {
        // 主循环,中断处理和DMA完成发送接收
    }
}
;