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Arduino/hardware/sam/variants/common/USART.cpp

139 lines
3.1 KiB
C++

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "USART.h"
// Constructors ////////////////////////////////////////////////////////////////
USARTClass::USARTClass( Usart* pUsart, IRQn_Type dwIrq, uint32_t dwId, RingBuffer* pRx_buffer, RingBuffer* pTx_buffer )
{
_rx_buffer = pRx_buffer ;
_tx_buffer = pTx_buffer ;
_pUsart=pUsart ;
_dwIrq=dwIrq ;
_dwId=dwId ;
}
// Public Methods //////////////////////////////////////////////////////////////
void USARTClass::begin( const uint32_t dwBaudRate )
{
/* Configure PMC */
PMC_EnablePeripheral( _dwId ) ;
/* Reset and disable receiver & transmitter */
_pUsart->US_CR = US_CR_RSTRX | US_CR_RSTTX | US_CR_RXDIS | US_CR_TXDIS ;
/* Configure mode */
_pUsart->US_MR = US_MR_USART_MODE_NORMAL | US_MR_USCLKS_MCK | US_MR_CHRL_8_BIT | US_MR_PAR_NO |
US_MR_NBSTOP_1_BIT | US_MR_CHMODE_NORMAL;
/* Configure baudrate */
/* Asynchronous, no oversampling */
_pUsart->US_BRGR = (SystemCoreClock / dwBaudRate) / 16 ;
/* Disable PDC channel */
_pUsart->US_PTCR = US_PTCR_RXTDIS | US_PTCR_TXTDIS ;
/* Enable receiver and transmitter */
_pUsart->US_CR = US_CR_RXEN | US_CR_TXEN ;
}
void USARTClass::end()
{
// wait for transmission of outgoing data
while ( _tx_buffer->_iHead != _tx_buffer->_iTail )
{
}
// clear any received data
_rx_buffer->_iHead = _rx_buffer->_iTail ;
PMC_DisablePeripheral( _dwId ) ;
}
int USARTClass::available( void )
{
return (unsigned int)(SERIAL_BUFFER_SIZE + _rx_buffer->_iHead - _rx_buffer->_iTail) % SERIAL_BUFFER_SIZE ;
}
int USARTClass::peek( void )
{
if ( _rx_buffer->_iHead == _rx_buffer->_iTail )
{
return -1 ;
}
else
{
return _rx_buffer->_aucBuffer[_rx_buffer->_iTail] ;
}
}
int USARTClass::read( void )
{
// if the _iHead isn't ahead of the _iTail, we don't have any characters
if ( _rx_buffer->_iHead == _rx_buffer->_iTail )
{
return -1 ;
}
else
{
unsigned char c = _rx_buffer->_aucBuffer[_rx_buffer->_iTail] ;
_rx_buffer->_iTail = (unsigned int)(_rx_buffer->_iTail + 1) % SERIAL_BUFFER_SIZE ;
return c ;
}
}
void USARTClass::flush( void )
{
while ( _tx_buffer->_iHead != _tx_buffer->_iTail )
{
}
}
void USARTClass::write( uint8_t uc )
{
int i = (_tx_buffer->_iHead + 1) % SERIAL_BUFFER_SIZE ;
// If the output buffer is full, there's nothing for it other than to
// wait for the interrupt handler to empty it a bit
while ( i == _tx_buffer->_iTail )
{
}
_tx_buffer->_aucBuffer[_tx_buffer->_iHead] = uc ;
_tx_buffer->_iHead = i ;
/* Wait for the transmitter to be ready */
while ( (_pUsart->US_CSR & US_CSR_TXEMPTY) == 0 ) ;
/* Send character */
_pUsart->US_THR=uc ;
}
void USARTClass::IrqHandler( void )
{
// RX char IT
uint8_t uc = _pUsart->US_RHR ;
_rx_buffer->store_char( uc ) ;
// TX FIFO empty IT
if ( _tx_buffer->_iHead == _tx_buffer->_iTail )
{
// Buffer empty, so disable interrupts
}
else
{
// There is more data in the output buffer. Send the next byte
uc = _tx_buffer->_aucBuffer[_tx_buffer->_iTail] ;
_tx_buffer->_iTail = (_tx_buffer->_iTail + 1) % SERIAL_BUFFER_SIZE ;
_pUsart->US_THR = uc ;
}
}