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之前的文章描述过STM32F10X USART DMA串口收发数据的文章，近期接触了STM32F4，使用习惯了USART DMA方式，就不愿意用中断的方式接收数据，了解了并习惯串口DMA后，还是觉得真香!
本文主要描述STM32F40X USART1 DMA的配置以及简单的测试。
相对于STM32F1的串口DMA配置，STM32F4的串口DMA相对更复杂一点儿，毕竟STM32F4的功能还是强大很多。
由于要配置STM32F4的USART1 DMA，根据datasheet的描述，做相应的配置
USART1的PA9-TX;PA10-RX
bsp_usart1_dma.c的配置代码
#include "bsp_usart1_dma.h"
uint8_t global_dma_recv_buf[LEN_USART1_RECV_BUF];
uint8_t global_dma_send_buf[LEN_USART1_RECV_BUF];
void init_usart1_dma(uint32_t bound)
{
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
DMA_InitTypeDef DMA_InitStructure;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);
GPIO_PinAFConfig(GPIOA,GPIO_PinSource9, GPIO_AF_USART1);
GPIO_PinAFConfig(GPIOA,GPIO_PinSource10, GPIO_AF_USART1);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
USART_InitStructure.USART_BaudRate = bound;
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);
DMA_DeInit(DMA2_Stream5);
while (DMA_GetCmdStatus(DMA2_Stream5) != DISABLE);
DMA_InitStructure.DMA_Channel = DMA_Channel_4;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&USART1->DR;
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)global_dma_recv_buf;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_InitStructure.DMA_BufferSize = LEN_USART1_RECV_BUF;
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_VeryHigh;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA2_Stream5, &DMA_InitStructure);
DMA_Cmd(DMA2_Stream5, ENABLE);
DMA_ClearITPendingBit(DMA2_Stream5, DMA_IT_TCIF5);
DMA_DeInit(DMA2_Stream7);
while (DMA_GetCmdStatus(DMA2_Stream7) != DISABLE);
DMA_InitStructure.DMA_Channel = DMA_Channel_4;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&USART1->DR;
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)global_dma_send_buf;
DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
DMA_InitStructure.DMA_BufferSize = 0;
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_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA2_Stream7, &DMA_InitStructure);
DMA_Cmd(DMA2_Stream7, DISABLE);
DMA_ClearITPendingBit(DMA2_Stream7, DMA_IT_TCIF7);
DMA_ClearFlag(DMA2_Stream7, DMA_FLAG_TCIF7);
USART_ClearFlag(USART1, USART_FLAG_TC);
USART_DMACmd(USART1, USART_DMAReq_Rx, ENABLE);
USART_DMACmd(USART1, USART_DMAReq_Tx, ENABLE);
USART_Cmd(USART1, ENABLE);
}
void fn_usart1_dma_send_bytes(uint8_t *bytes, uint8_t bytes_len)
{
DMA_Cmd(DMA2_Stream7, DISABLE);
memcpy(global_dma_send_buf, bytes, bytes_len);
while (DMA_GetCmdStatus(DMA2_Stream7) != DISABLE);
DMA_SetCurrDataCounter(DMA2_Stream7, bytes_len);
DMA_Cmd(DMA2_Stream7, ENABLE);
while(DMA_GetCurrDataCounter(DMA2_Stream7));
while(USART_GetFlagStatus(USART1, USART_FLAG_TC) != SET);
DMA_ClearFlag(DMA2_Stream7 , DMA_FLAG_TCIF7 | DMA_FLAG_FEIF7 | DMA_FLAG_DMEIF7 | DMA_FLAG_TEIF7 | DMA_FLAG_HTIF7);
}
uint8_t fn_usart1_dma_recv_bytes(uint8_t *recv_buf, uint16_t *len_recv)
{
uint16_t len_dma_recv = 0;
if(USART_GetFlagStatus(USART1, USART_FLAG_IDLE) != RESET)
{
USART_ReceiveData(USART1);
DMA_Cmd(DMA2_Stream5, DISABLE);
len_dma_recv = LEN_USART1_RECV_BUF - DMA_GetCurrDataCounter(DMA2_Stream5);
memcpy(recv_buf, global_dma_recv_buf, len_dma_recv);
DMA_SetCurrDataCounter(DMA2_Stream5, LEN_USART1_RECV_BUF);
USART_ClearFlag(USART1, USART_FLAG_IDLE);
DMA_ClearFlag(DMA2_Stream5 , DMA_FLAG_TCIF5 | DMA_FLAG_FEIF5 | DMA_FLAG_DMEIF5 | DMA_FLAG_TEIF5 | DMA_FLAG_HTIF5);
DMA_Cmd(DMA2_Stream5, ENABLE);
}
if(len_dma_recv <= 0)
{
return 1;
}
else if(len_dma_recv > LEN_USART1_RECV_BUF)
{
return 2;
}
*len_recv = len_dma_recv;
return 0;
}
bsp_usart1_dma.h的代码
#ifndef __BSP_USART1_H
#define __BSP_USART1_H
#include <stm32f4xx.h>
#include <string.h>
#define LEN_USART1_RECV_BUF 256
void init_usart1_dma(uint32_t bound);
void fn_usart1_dma_send_bytes(uint8_t *bytes, uint8_t bytes_len);
uint8_t fn_usart1_dma_recv_bytes(uint8_t *recv_buf, uint16_t *len_recv);
#endif
main.c测试主函数代码（发啥回啥）
#include <stm32f4xx.h>
#include "bsp_led.h"
#include "bsp_beep.h"
#include "util_time.h"
#include "bsp_usart1_dma.h"
int main(void)
{
uint8_t buf[256];
uint16_t len;
uint8_t suc;
init_led();
init_beep();
init_usart1_dma(19200);
func_beep_play();
func_led0_on();
delay_ms(200);
func_beep_stop();
delay_s(1);
for(;;)
{
suc = fn_usart1_dma_recv_bytes(buf, &len);
if(suc == 0)
{
fn_usart1_dma_send_bytes(buf, len);
}
func_led1_on();
delay_ms(100);
func_led1_off();
delay_ms(100);
}
}
测试效果如下：
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