关于DMA连续发送字符串的几个问题

zbf15 · 发表于 2015-4-9 18:11:42

我参照DMA未知长度数据接收和发送的程序写了DMA的程序，可以实现单次的接受发送，但是遇到了几个问题，新手不会解决，特来求问~

1.如何实现连续的DMA发送呢？运用这个中断函数，可以在中断中判断接收到的字符串。如果我想在判断接收到的字符串满足某个要求后，触发一连串的循环的DMA发送，该怎么实现？比如我从CAN总线一直有数据传过来，这边在DMA怎么连续地发送出去？

2.我想利用memcmp函数判断字符串是否满足要求，用if语句判断：if(memcmp(ReceiveBuff,collect,1)==0)
但是在这个中断里接收字符串总是与实际不同，不知道是什么原因，如果我将ReceiveBuff赋给SendBuff，send出去的字符串又是相同的，是因为在中断过程中字符串的接收还没有完成？

下面附上中断函数的代码

[mw_shl_code=c,true]void USART2_IRQHandler(void) { u16 DATA_LEN; u16 i; // printf("1\r\n"); if(USART_GetITStatus(USART2, USART_IT_IDLE) == RESET)//!=change to == { DMA_Cmd(DMA1_Channel6, DISABLE);//??±?DMA,·??????í?????????? //USART_RX_STA = USART2->SR;//????SR?????ó??DR???????? //USART_RX_STA = USART2->DR; DATA_LEN=512-DMA_GetCurrDataCounter(DMA1_Channel6); // printf("2\r\n"); if(DATA_LEN > 0) { while(USART2_TX_Finish==0) { ; } //????????DMA???????· //----------------------------------------------------------------- if(memcmp(ReceiveBuff,collect,1)==0) strcpy(SendBuff,get); else strcpy(SendBuff,ReceiveBuff); // if(memcmp(ReceiveBuff,collect,strlen(collect))==0) // strcpy(SendBuff,get); // else // strcpy(SendBuff,ReceiveBuff); //----------------------------------------------------------------- //USART??DMA???????ú?é??·???·???????·?±????????????????ú?ú???????ó?? DMA_Cmd(DMA1_Channel7, DISABLE); //??±?datasize?°?????????¨???¤×÷ DMA1_Channel7->CNDTR=DATA_LEN; //DMA1,?????????? USART2_TX_Finish=0;//DMA????????±ê???? DMA_Cmd(DMA1_Channel7, ENABLE); //·??? } //DMA_Cmd(DMA1_Channel5, DISABLE);//??±?DMA,·??????í?????????? DMA_ClearFlag(DMA1_FLAG_GL6 | DMA1_FLAG_TC6 | DMA1_FLAG_TE6 | DMA1_FLAG_HT6);//??±ê?? DMA1_Channel6->CNDTR = 512;//??×°?? DMA_Cmd(DMA1_Channel6, ENABLE);//???í?ê,????DMA //??SR?ó??DR????Idle i = USART2->SR; i = USART2->DR; } if(USART_GetITStatus(USART2, USART_IT_PE | USART_IT_FE | USART_IT_NE) != RESET)//???í { USART_ClearITPendingBit(USART2, USART_IT_PE | USART_IT_FE | USART_IT_NE); } USART_ClearITPendingBit(USART2, USART_IT_TC); USART_ClearITPendingBit(USART2, USART_IT_IDLE); // Delay(10000); // printf("%s\r\n",SendBuff); // Delay(10000); }[/mw_shl_code]