关于dma接收的问题

你干嘛 · 发表于 2014-11-16 18:16:31

程序为pc机发送字符串到串口，由dma接收，且一直等待接收100%，接收完成后，再发送回pc机上
现在有如下问题：
当程序执行到MY_DMA_CONFIG(DMA1_Channel5,(u32)&USART1->DR,(u32)Receive_Buff,10);也就是配置完之后，而串口1的dma并没有使能接收，奇怪的是此时如果pc机通过串口发送数据，比如“1”，然后在按键按下之后，执行到MYDMA_Enable(DMA1_Channel5);//开始进行一次传输；却发现Receive_Buff[]里第一个数据为“1”了，应该并没有使能才对啊，为什么在使能之前发送的数据会传到Receive_Buff[]中呢，而且只有“1”传到Receive_Buff[]里了，回车的0x0d和0x0a却没传进去

后来发现在USART_Cmd(USART1, ENABLE);这句话之后，好像就给串口1留了一个位置，不管串口1的dma是否使能接收，都能收到第一个数，而且第一个数不能被覆盖，不知道有没有人和我遇到一样的问题，求解，下面附上程序

你干嘛 · 发表于 2014-11-16 18:16:32

回复【4楼】正点原子:
---------------------------------
谢原子哥帮顶啊，主要是我的问题说的不是很清楚。。我想我找到原因了，是因为之前使能了串口，因此串口的BUF能收到数据，而且只能放一个，由于没有使能DMA，所以数据没有被移走，一直在BUF中，直到DMA使能后，数据被DMA移到了RECEIVE_BUF，而后，传到串口BUF的数据便能被DMA搬到RECEIVE_BUF中了，总的来说，DMA只是一个搬运工

请问原子哥，串口的接收BUF是不是不能被覆盖的？

你干嘛 · 发表于 2014-11-16 18:18:11

#include "led.h"
#include "delay.h"
#include "key.h"
#include "sys.h"
#include "lcd.h"
#include "usart.h"
#include "dma.h"
//ALIENTEK????STM32??·?°????é21
//DMA ???é
//?????§????www.openedv.com
//?????????í??×?????????????
u8 Receive_Buff[20];

void usart_init(void)
{
USART_InitTypeDef USART_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_USART1, ENABLE);
USART_DeInit(USART1);  //????????1
//USART1_TX
    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
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    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_Tx | USART_Mode_Rx;
    USART_Init(USART1, &USART_InitStructure);

    USART_Cmd(USART1, ENABLE);
}

int main(void)
{
u16 i;
u8 t=0;
float pro=0;//????

delay_init();      //???±??????????
NVIC_Configuration(); //?è??NVIC????·?×é2:2??????????????2???ì????????
//uart_init(9600); //????????????9600
usart_init();//??????????
LED_Init();      //LED??????????
LCD_Init(); //??????LCD
KEY_Init(); //°??ü??????

MY_DMA_CONFIG(DMA1_Channel5,(u32)&USART1->DR,(u32)Receive_Buff,10);//DMA1?¨??5,???è??????1,?????÷??Receive_Buff,?¤??88.

POINT_COLOR=RED;//?è??×??????ì??
LCD_ShowString(60,50,200,16,16,"WarShip STM32");
LCD_ShowString(60,70,200,16,16,"DMA TEST");
LCD_ShowString(60,90,200,16,16,"ATOM@ALIENTEK");
LCD_ShowString(60,110,200,16,16,"2012/9/8");
  LCD_ShowString(60,130,200,16,16,"KEY0:Start");
//USART_Cmd(USART1, DISABLE);//?ó??????????????USART????°??ü°??????ó????????????????????
while(1)
{
t=KEY_Scan(0);
if(t==KEY_RIGHT)//KEY0°???
{
LCD_ShowString(60,150,200,16,16,"Start Transimit....");
LCD_ShowString(60,170,200,16,16,"   %");//????°?·???
USART_Cmd(USART1, ENABLE);
printf("\r\nDMA DATA:\r\n");
// MY_DMA_CONFIG(DMA1_Channel5,(u32)&USART1->DR,(u32)Receive_Buff,10);//DMA1?¨??5,???è??????1,?????÷??Receive_Buff,?¤??88.
USART_DMACmd(USART1,USART_DMAReq_Rx,ENABLE); //????????1??DMA????
MYDMA_Enable(DMA1_Channel5);//????????DMA??????
    //????DMA?????ê???????±??????×??í??????????????
    //???????????????????????????????????í????????
    while(1)
    {
if(DMA_GetFlagStatus(DMA1_FLAG_TC5)!=RESET) //?????¨??5?????ê??
{
DMA_ClearFlag(DMA1_FLAG_TC5);//?????¨??5?????ê??±ê??
printf("%s",Receive_Buff);
printf("end");
break;
}
pro=DMA_GetCurrDataCounter(DMA1_Channel5);//?????±?°?????à?à????????
pro=1-pro/10;//????°?·?±?
pro*=100;      //???ó100±?
LCD_ShowNum(60,170,pro,3,16);
    }
LCD_ShowNum(60,170,100,3,16);//????100%
LCD_ShowString(60,150,200,16,16,"Transimit Finished!");//?á???????ê??
}
i++;
delay_ms(10);
if(i==20)
{
LED0=!LED0;//?á??????????????
i=0;
}
}
}
这。。不知道怎么复制。。中文注释都成乱码了，请大家勉强看下吧

你干嘛 · 发表于 2014-11-16 18:19:16

//????????DMA????
void MYDMA_Enable(DMA_Channel_TypeDef*DMA_CHx)
{
DMA_Cmd(DMA_CHx, DISABLE );  //??±?USART1 TX DMA1 ?ù???????¨??
DMA_SetCurrDataCounter(DMA1_Channel4,DMA1_MEM_LEN);//DMA?¨????DMA???????ó??
DMA_Cmd(DMA_CHx, ENABLE);  //????USART1 TX DMA1 ?ù???????¨??
}

/********    test    ***********/
void MY_DMA_CONFIG(DMA_Channel_TypeDef* DMA_CHx,u32 cpar,u32 cmar,u16 cndtr)
{
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); //????DMA????

  DMA_DeInit(DMA_CHx);   //??DMA???¨??1?????÷???è???±????
DMA1_MEM_LEN=cndtr;//cndtr±í?????????????¤??
DMA_InitStructure.DMA_PeripheralBaseAddr = cpar;  //DMA???èADC?ù???·
DMA_InitStructure.DMA_MemoryBaseAddr = cmar;  //DMA?????ù???·
// DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;  //????????·??ò????????????·????????è
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;//????????·??ò???????è????·?????????
DMA_InitStructure.DMA_BufferSize = cndtr;  //DMA?¨????DMA???????ó??
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;  //???è???·?????÷??±?
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;  //???????·?????÷????
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;  //?????í????8??
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte; //?????í????8??
//DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;  //?¤×÷??????????????
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;//?????????¤×÷?????·????
DMA_InitStructure.DMA_Priority = DMA_Priority_Medium; //DMA?¨?? x????????????
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;  //DMA?¨??x?????è??????????????????
DMA_Init(DMA_CHx, &DMA_InitStructure);  //?ù??DMA_InitStruct?????¨????????????DMA???¨??USART1_Tx_DMA_Channel?ù±ê?????????÷

}