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Implement transmit buffering with interrupts for USART devices

This commit is contained in:
Collin Kidder 2014-12-21 20:57:08 -05:00
parent 588f9f1118
commit 065459c18f
3 changed files with 39 additions and 11 deletions
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38
hardware/arduino/sam/cores/arduino/USARTClass.cpp
View File

@ -23,15 +23,17 @@
// Constructors ////////////////////////////////////////////////////////////////
USARTClass::USARTClass( Usart* pUsart, IRQn_Type dwIrq, uint32_t dwId, RingBuffer* pRx_buffer )
USARTClass::USARTClass( Usart* pUsart, IRQn_Type dwIrq, uint32_t dwId, RingBuffer* pRx_buffer, volatile RingBuffer* pTx_buffer )
{
_rx_buffer = pRx_buffer ;
_rx_buffer = pRx_buffer;
_tx_buffer = pTx_buffer;
_pUsart=pUsart ;
_dwIrq=dwIrq ;
_dwId=dwId ;
}
// Public Methods //////////////////////////////////////////////////////////////
void USARTClass::begin( const uint32_t dwBaudRate )
@ -73,6 +75,8 @@ void USARTClass::end( void )
// clear any received data
_rx_buffer->_iHead = _rx_buffer->_iTail ;
while (_tx_buffer->_iHead != _tx_buffer->_iTail); //wait for transmit data to be sent
// Disable UART interrupt in NVIC
NVIC_DisableIRQ( _dwIrq ) ;
@ -115,12 +119,21 @@ void USARTClass::flush( void )
size_t USARTClass::write( const uint8_t uc_data )
{
// Check if the transmitter is ready
while ((_pUsart->US_CSR & US_CSR_TXRDY) != US_CSR_TXRDY)
;
if ((_pUsart->US_CSR & US_CSR_TXRDY) != US_CSR_TXRDY) //is the hardware currently busy?
{
//if busy we buffer
unsigned int l = (_tx_buffer->_iHead + 1) % SERIAL_BUFFER_SIZE;
while (_tx_buffer->_iTail == l); //spin locks if we're about to overwrite the buffer. This continues once the data is sent
// Send character
_pUsart->US_THR = uc_data ;
_tx_buffer->_aucBuffer[_tx_buffer->_iHead] = uc_data;
_tx_buffer->_iHead = l;
_pUsart->US_IER = US_IER_TXRDY; //make sure TX interrupt is enabled
}
else
{
// Send character
_pUsart->US_THR = uc_data ;
}
return 1;
}
@ -132,6 +145,17 @@ void USARTClass::IrqHandler( void )
if ((status & US_CSR_RXRDY) == US_CSR_RXRDY)
_rx_buffer->store_char( _pUsart->US_RHR ) ;
//Do we need to keep sending data?
if ((status & US_CSR_TXRDY) == US_CSR_TXRDY)
{
_pUsart->US_THR = _tx_buffer->_aucBuffer[_tx_buffer->_iTail];
_tx_buffer->_iTail = (unsigned int)(_tx_buffer->_iTail + 1) % SERIAL_BUFFER_SIZE;
if (_tx_buffer->_iTail == _tx_buffer->_iHead) //if this is true we have no more data to transmit
{
_pUsart->US_IDR = US_IDR_TXRDY; //mask off transmit interrupt so we don't get it anymore
}
}
// Acknowledge errors
if ((status & US_CSR_OVRE) == US_CSR_OVRE ||
(status & US_CSR_FRAME) == US_CSR_FRAME)

3
hardware/arduino/sam/cores/arduino/USARTClass.h
View File

@ -60,6 +60,7 @@ class USARTClass : public HardwareSerial
{
protected:
RingBuffer *_rx_buffer ;
volatile RingBuffer *_tx_buffer;
protected:
Usart* _pUsart ;
@ -67,7 +68,7 @@ class USARTClass : public HardwareSerial
uint32_t _dwId ;
public:
USARTClass( Usart* pUsart, IRQn_Type dwIrq, uint32_t dwId, RingBuffer* pRx_buffer ) ;
USARTClass( Usart* pUsart, IRQn_Type dwIrq, uint32_t dwId, RingBuffer* pRx_buffer, volatile RingBuffer* pTx_buffer ) ;
void begin( const uint32_t dwBaudRate ) ;
void begin( const uint32_t dwBaudRate , const uint32_t config ) ;

9
hardware/arduino/sam/variants/arduino_due_x/variant.cpp
View File

@ -317,14 +317,17 @@ void UART_Handler(void)
RingBuffer rx_buffer2;
RingBuffer rx_buffer3;
RingBuffer rx_buffer4;
volatile RingBuffer tx_buffer2;
volatile RingBuffer tx_buffer3;
volatile RingBuffer tx_buffer4;
USARTClass Serial1(USART0, USART0_IRQn, ID_USART0, &rx_buffer2);
USARTClass Serial1(USART0, USART0_IRQn, ID_USART0, &rx_buffer2, &tx_buffer2);
void serialEvent1() __attribute__((weak));
void serialEvent1() { }
USARTClass Serial2(USART1, USART1_IRQn, ID_USART1, &rx_buffer3);
USARTClass Serial2(USART1, USART1_IRQn, ID_USART1, &rx_buffer3, &tx_buffer3);
void serialEvent2() __attribute__((weak));
void serialEvent2() { }
USARTClass Serial3(USART3, USART3_IRQn, ID_USART3, &rx_buffer4);
USARTClass Serial3(USART3, USART3_IRQn, ID_USART3, &rx_buffer4, &tx_buffer4);
void serialEvent3() __attribute__((weak));
void serialEvent3() { }