DMA求教

humble

我用DMA来提取电子罗盘的信号，电子罗盘是那种模块化了的，返回值稍作处理即可读出倾角值。我用USART3连接电子罗盘，可是接收不到信号返回，
而直接用FT232是可以读到返回值的，不知是不是程序的问题？还请各位大神帮忙看看。下面上代码：

#include "stm32f10x.h"

#include "SysTickDelay.h"

#include "compass.h" 

u8 USART_RX_BUF[14];        //接收缓冲,最大14个字节.

//接收状态

u8 USART_RX_STA=0;          //接收状态标记

float heading_degree=0;

u8 sign=0;

u8 i=0;

void DMA_Config(void)

{

    //GPIO端口设置

    GPIO_InitTypeDef GPIO_InitStructure;

USART_InitTypeDef USART_InitStructure;

DMA_InitTypeDef DMA_InitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3,ENABLE); //使能USART3时钟

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1|RCC_APB2Periph_GPIOA|RCC_APB2Periph_GPIOB|RCC_APB2Periph_AFIO, ENABLE);//使能USART1和GPIOB时钟

     //USART3_TX   PB.10

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;

    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

    GPIO_Init(GPIOB, &GPIO_InitStructure);

   

    //USART3_RX  B.11

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

    GPIO_Init(GPIOB, &GPIO_InitStructure); 

//USART1_TX   PA.9

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;

    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

    GPIO_Init(GPIOA, &GPIO_InitStructure);

   

    //USART1_RX  A.10

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

    GPIO_Init(GPIOA, &GPIO_InitStructure); 

   //USART 初始化设置

   

USART_InitStructure.USART_BaudRate = 9600;//设置波特率，一般为9600;

USART_InitStructure.USART_WordLength = USART_WordLength_8b;//设置有效位

USART_InitStructure.USART_StopBits = USART_StopBits_1; //设置停止位

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(USART3, &USART_InitStructure);

USART_Init(USART1, &USART_InitStructure);

   

    USART_Cmd(USART3, ENABLE); 

USART_Cmd(USART1, ENABLE);                    //使能串口 

    /* DMA clock enable */

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

/* USARTy RX DMA1 Channel (triggered by USARTy Rx event) Config */

DMA_DeInit(DMA1_Channel3); 

DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)USART3->DR;  //DMA外设地址

DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)USART_RX_BUF;

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

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_VeryHigh;

DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;

DMA_InitStructure.DMA_BufferSize = 8;

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;

DMA_Init(DMA1_Channel3, &DMA_InitStructure);

/* Enable USARTy DMA Rx and TX request */

  USART_DMACmd(USART3, USART_DMAReq_Rx, ENABLE);

/* Enable USARTy RX DMA1 Channel */

DMA_Cmd(DMA1_Channel3, ENABLE);

}

//校准罗盘初始角度

void cali(void)

{

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}  //发送校准命令

USART_SendData(USART3, 0x68);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x04);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x00);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x08);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x0C);

}

//保存校准

void save_cali(void)

{

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}   //发送保存校准命令

USART_SendData(USART3, 0x68);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x05);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x00);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x8A);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x00);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x8F);

}

//读取磁偏角

float Read_heading(void)

{

/* Wait until USARTy RX DMA1 Channel Transfer Complete */

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {} //发送读取磁偏角命令

USART_SendData(USART3, 0x68);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x04);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x00);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x04);

while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET) {}

USART_SendData(USART3, 0x08);

while (DMA_GetFlagStatus(DMA1_FLAG_TC3) == RESET)

{

}

for(i=0;i<14;i++) //将电子罗盘的回应发送到串口1，利用串口调试助手接收结果

{

USART_SendData(USART1, USART_RX_BUF);

}

sign=USART_RX_BUF[11]&0x80; //判断符号的正负

heading_degree=(USART_RX_BUF[11]&0x0F)*100+(USART_RX_BUF[12]/16*10)+(USART_RX_BUF[12]%16)+(USART_RX_BUF[13]/16*10)+(USART_RX_BUF[13]%16)/100;

if (sign==0x80)

{

heading_degree=-heading_degree; //计算磁偏角

}

ms_Delay(50);

return heading_degree;

}

正点原子

先不用DMA试试吧，一开始就把程序搞得这么复杂...要学会从简单到复杂。