Demo/PIC32MX_MPLAB/serial/serial.c

/*
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	of http://www.FreeRTOS.org for full details.


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*/


/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. 

NOTE:  This driver is primarily to test the scheduler functionality.  It does
not effectively use the buffers or DMA and is therefore not intended to be
an example of an efficient driver. */

/* Standard include file. */
#include <stdlib.h>
#include <plib.h>

/* Scheduler include files. */
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"

/* Demo app include files. */
#include "serial.h"

/* Hardware setup. */
#define serSET_FLAG						( 1 )

/* The queues used to communicate between tasks and ISR's. */
static xQueueHandle xRxedChars; 
static xQueueHandle xCharsForTx; 

/* Flag used to indicate the tx status. */
static portBASE_TYPE xTxHasEnded;

/*-----------------------------------------------------------*/

/* The UART interrupt handler. */
void __attribute__( (interrupt(ipl1), vector(_UART2_VECTOR))) vU2InterruptWrapper( void );

/*-----------------------------------------------------------*/

xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
unsigned portSHORT usBRG;

	/* Create the queues used by the com test task. */
	xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
	xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );

	/* Configure the UART and interrupts. */
	usBRG = (unsigned portSHORT)(( (float)configPERIPHERAL_CLOCK_HZ / ( (float)16 * (float)ulWantedBaud ) ) - (float)0.5);
	OpenUART2( UART_EN, UART_RX_ENABLE | UART_TX_ENABLE | UART_INT_TX | UART_INT_RX_CHAR, usBRG );
	ConfigIntUART2( ( configKERNEL_INTERRUPT_PRIORITY + 1 ) | UART_INT_SUB_PR0 | UART_TX_INT_EN | UART_RX_INT_EN );

	xTxHasEnded = pdTRUE;

	/* Only a single port is implemented so we don't need to return anything. */
	return NULL;
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
{
	/* Only one port is supported. */
	( void ) pxPort;

	/* Get the next character from the buffer.  Return false if no characters
	are available or arrive before xBlockTime expires. */
	if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
	{
		return pdTRUE;
	}
	else
	{
		return pdFALSE;
	}
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
{
	/* Only one port is supported. */
	( void ) pxPort;

	/* Return false if after the block time there is no room on the Tx queue. */
	if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
	{
		return pdFAIL;
	}

	/* A critical section should not be required as xTxHasEnded will not be
	written to by the ISR if it is already 0 (is this correct?). */
	if( xTxHasEnded )
	{
		xTxHasEnded = pdFALSE;
		IFS1bits.U2TXIF = serSET_FLAG;
	}

	return pdPASS;
}
/*-----------------------------------------------------------*/

void vSerialClose( xComPortHandle xPort )
{
}
/*-----------------------------------------------------------*/

void vU2InterruptHandler( void )
{
/* Declared static to minimise stack use. */
static portCHAR cChar;
static portBASE_TYPE xHigherPriorityTaskWoken;

	xHigherPriorityTaskWoken = pdFALSE;

	/* Are any Rx interrupts pending? */
	if( mU2RXGetIntFlag() )
	{
		while( U2STAbits.URXDA )
		{
			/* Retrieve the received character and place it in the queue of
			received characters. */
			cChar = U2RXREG;
			xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
		}
		mU2RXClearIntFlag();
	}

	/* Are any Tx interrupts pending? */
	if( mU2TXGetIntFlag() )
	{
		while( !( U2STAbits.UTXBF ) )
		{
			if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
			{
				/* Send the next character queued for Tx. */
				U2TXREG = cChar;
			}
			else
			{
				/* Queue empty, nothing to send. */
				xTxHasEnded = pdTRUE;
				break;
			}
		}

		mU2TXClearIntFlag();
	}

	/* If sending or receiving necessitates a context switch, then switch now. */
	portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
}