Posted on February 16, 2018 at 02:19Are you using the cube ?
I initialise the RXDMA once in startup.
void initUart1RxDMABuffer(void) {
if (HAL_UART_Receive_DMA(&huart1, (uint8_t *)Usart1RxDMABuffer, U1RxBufSize) != HAL_OK)
{
// Transfer error in reception process
//_Error_Handler(__FILE__, __LINE__);
char string[32];
sprintf(string, 'initUart1RxDMABuffer Failed\n');
puts1(string);
}
else
{
char string[32];
sprintf(string, 'initUart1RxDMABuffer OK!\n');
puts1(string);
}
}
as I add bytes to the transmit DMA buffer, I set the flag TxDMA1BufHasData
void putc1(char saveByte) {
checkU1TxDMABufferLength(); //using normal buffer, not circular.
Usart1TxDMABuffer[U1TxBufferPtrIN++] = saveByte;
U1TxBufferPtrIN &= U1TxBufSize - 1;
TxDMA1BufHasData = true; <- here
}
then in the foreground, I check if we need to initialse a txDMA stream. if there is data to send
CheckTx1DMA(){ <- check it here in foreground
if (TxDMA1BufHasData) { <- check it here in foreground
char uartState = HAL_UART_GetState(&huart1);
if ((uartState == HAL_UART_STATE_READY) || (uartState == HAL_UART_STATE_BUSY_RX)) {
TxDMA1BufHasData = false; // sending now
if(HAL_UART_Transmit_DMA(&huart1, (uint8_t *)Usart1TxDMABuffer + U1TxBufferPtrOUT, U1TxBufferPtrIN - U1TxBufferPtrOUT) == HAL_OK) {
U1TxBufferPtrOUT = U1TxBufferPtrIN;
Usart1TxDMABuffer[U1TxBufferPtrIN] = 0 ; // null
}
else {
_Error_Handler(__FILE__, __LINE__); /* Transfer error in transmission process */
}
}
}
}
char readableU1(void){
U1RxBufferPtrIN = U1RxBufSize - huart1.hdmarx->Instance->CNDTR;
return U1RxBufferPtrIN - U1RxBufferPtrOUT;
}
char getc1(void) {
char Rxbyte = Usart1RxDMABuffer[U1RxBufferPtrOUT++];
if (U1RxBufferPtrOUT >= U1RxBufSize) U1RxBufferPtrOUT = 0;
return Rxbyte;
}
basic example:
// initialise Serial port 1 TxRxDMA buffer pointers
TxDMA1BufHasData = false;
U1TxBufferPtrIN = 0; U1TxBufferPtrOUT = 0;
U1RxBufferPtrIN = 0; U1RxBufferPtrOUT = 0;
DMA1BufAlmostFull = false;
TxDMA1BufHasData = false;
initUart1RxDMABuffer();
while(1){
if ( mS has changed) // every mS
CheckTx1DMA(); // check anywhere in the foreground
}
in any function:
char string[32];
sprintf(string, ' processor temp is %d degrees\n', 42.3);
puts1(string);
if (readableU1())
{
char readByte = readU1();
if (readByte == 't')
getFreshLoRaPacket = true; // from the CAN Rx packets pushed into a LoRa packet
else ...
