/**
* @brief Get a complete frame from USART2 (nonblocking)
* @param buf Buffer for data (data will be null terminated for easier string manipulation)
* @param len Length not including terminator character
* @retval 0 Received frame
* @retval 1 No frame in buffer
* @retval 2 Frame error
* TODO Add maximum length checking so as not to overflow
*/
int COMM_GetFrame(uint8_t* buf, uint8_t* len) {
uint8_t c;
*len = 0; // zero out length variable
if (gotFrame) {
while (1) {
// no more data and terminator wasn't reached => error
if (FIFO_IsEmpty(&rxFifo)) {
*len = 0;
println("Invalid frame");
return 2;
}
FIFO_Pop(&rxFifo, &c);
buf[(*len)++] = c;
// if end of frame
if (c == COMM_TERMINATOR) {
(*len)--; // length without terminator character
buf[*len] = 0; // USART terminator character converted to NULL terminator
break;
}
}
gotFrame--;
return 0;
} else {
return 1;
}
}
/**
* @brief IRQ handler for USART2
*/
void USART2_IRQHandler(void) {
// If transmit buffer empty interrupt
if(USART_GetITStatus(USART2, USART_IT_TXE) != RESET) {
uint8_t c;
if (FIFO_Pop(&txFifo,&c) == 0) { // If buffer not empty
USART_SendData(USART2, c); // Send data
} else {
// Turn off TXE interrupt
USART_ITConfig(USART2, USART_IT_TXE, DISABLE);
}
}
// If RX buffer not empty interrupt
if(USART_GetITStatus(USART2, USART_IT_RXNE) != RESET) {
uint8_t c = USART_ReceiveData(USART2); // Get data from UART
uint8_t res = FIFO_Push(&rxFifo, c); // Put data in RX buffer
// Checking res to ensure no buffer overflow occurred
if ((c == UART2_TERMINATOR) && (res == 0)) {
gotFrame++;
}
}
}
/**
* @brief Callback for transmitting data to lower layer
* @param c Transmitted data
* @retval 0 There is no more data in buffer (stop transmitting)
* @retval 1 Valid data in c
*/
uint8_t COMM_TxCallback(uint8_t* c) {
if (FIFO_Pop(&txFifo, c) == 0) { // If buffer not empty
return 1;
} else {
return 0;
}
}
/**
* @brief Get a char from USART2
* @return Received char.
* @warning Blocking function! Waits until char is received.
*/
char COMM_Getc(void) {
uint8_t c;
while (FIFO_IsEmpty(&rxFifo) == 1); // wait until buffer is not empty
// buffer not empty => char was received
FIFO_Pop(&rxFifo,&c); // Get data from RX buffer
return c;
}
/**
* @brief Callback for transmitting data to lower layer
* @param c Transmitted data
* @retval 0 There is no more data in buffer (stop transmitting)
* @retval 1 Valid data in c
*/
int COMM_TxCallback(char* buf) {
if (FIFO_IsEmpty(&txFifo)) {
return 0;
}
// get all the data at one go
int i = 0;
while (!FIFO_Pop(&txFifo, buf+i)) {
i++;
}
return i;
}
/**
* @brief Get a char from USART2
* @return Received char.
* @warning Blocking function!
*/
uint8_t USART2_Getc(void) {
uint8_t c;
while (FIFO_IsEmpty(&rxFifo) == 1); // wait until buffer is not empty
// buffer not empty => char was received
USART_ITConfig(USART2, USART_IT_RXNE, DISABLE); // disable RX interrupt
FIFO_Pop(&rxFifo,&c); // Get data from RX buffer
USART_ITConfig(USART2, USART_IT_RXNE, ENABLE); // enable RX interrupt
return c;
}
void USART3_IRQHandler(void)
{
if(USART_GetITStatus(USART3, USART_IT_TXE) != RESET)
{
while(!FIFO_IsEmpty(usart3_tx_fifo))
{
uint8_t tx_data;
FIFO_Pop(usart3_tx_fifo, &tx_data);
while (USART_GetFlagStatus(USART3,USART_FLAG_TC) == RESET);
USART_SendData(USART3, tx_data);
}
USART_ITConfig(USART3, USART_IT_TXE, DISABLE);
}
else if(USART_GetITStatus(USART3, USART_IT_RXNE) != RESET)
{
uint8_t rx_data = USART_ReceiveData(USART3);
}
}