20100923-V6.1.0-RC2/Demo/Cygnal/serial/serial.c

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+/*
+    FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd.
+
+    ***************************************************************************
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+
+    This file is part of the FreeRTOS distribution.
+
+    FreeRTOS is free software; you can redistribute it and/or modify it under
+    the terms of the GNU General Public License (version 2) as published by the
+    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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+    a combined work that includes FreeRTOS without being obliged to provide the
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+    License and the FreeRTOS license exception along with FreeRTOS; if not it 
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+    by writing to Richard Barry, contact details for whom are available on the
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+*/
+
+
+/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR DEMO PURPOSES */
+#include <stdlib.h>
+#include "FreeRTOS.h"
+#include "queue.h"
+#include "task.h"
+#include "serial.h"
+
+/* Constants required to setup the serial control register. */
+#define ser8_BIT_MODE			( ( unsigned char ) 0x40 )
+#define serRX_ENABLE			( ( unsigned char ) 0x10 )
+
+/* Constants to setup the timer used to generate the baud rate. */
+#define serCLOCK_DIV_48			( ( unsigned char ) 0x03 )
+#define serUSE_PRESCALED_CLOCK	( ( unsigned char ) 0x10 )
+#define ser8BIT_WITH_RELOAD		( ( unsigned char ) 0x20 )
+#define serSMOD					( ( unsigned char ) 0x10 )
+
+static xQueueHandle xRxedChars; 
+static xQueueHandle xCharsForTx; 
+
+data static unsigned portBASE_TYPE uxTxEmpty;
+
+/*-----------------------------------------------------------*/
+
+xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
+{
+unsigned long ulReloadValue;
+const portFLOAT fBaudConst = ( portFLOAT ) configCPU_CLOCK_HZ * ( portFLOAT ) 2.0;
+unsigned char ucOriginalSFRPage;
+
+	portENTER_CRITICAL();
+	{
+		ucOriginalSFRPage = SFRPAGE;
+		SFRPAGE = 0;
+
+		uxTxEmpty = pdTRUE;
+
+		/* Create the queues used by the com test task. */
+		xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
+		xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
+	
+		/* Calculate the baud rate to use timer 1. */
+		ulReloadValue = ( unsigned long ) ( ( ( portFLOAT ) 256 - ( fBaudConst / ( portFLOAT ) ( 32 * ulWantedBaud ) ) ) + ( portFLOAT ) 0.5 );
+
+		/* Set timer one for desired mode of operation. */
+		TMOD &= 0x08;
+		TMOD |= ser8BIT_WITH_RELOAD;
+		SSTA0 |= serSMOD;
+
+		/* Set the reload and start values for the time. */
+		TL1 = ( unsigned char ) ulReloadValue;
+		TH1 = ( unsigned char ) ulReloadValue;
+
+		/* Setup the control register for standard n, 8, 1 - variable baud rate. */
+		SCON = ser8_BIT_MODE | serRX_ENABLE;
+
+		/* Enable the serial port interrupts */
+		ES = 1;
+
+		/* Start the timer. */
+		TR1 = 1;
+
+		SFRPAGE = ucOriginalSFRPage;
+	}
+	portEXIT_CRITICAL();
+	
+	/* Unlike some ports, this serial code does not allow for more than one
+	com port.  We therefore don't return a pointer to a port structure and can
+	instead just return NULL. */
+	return NULL;
+}
+/*-----------------------------------------------------------*/
+
+void vSerialISR( void ) interrupt 4
+{
+char cChar;
+portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
+
+	/* 8051 port interrupt routines MUST be placed within a critical section
+	if taskYIELD() is used within the ISR! */
+
+	portENTER_CRITICAL();
+	{
+		if( RI ) 
+		{
+			/* Get the character and post it on the queue of Rxed characters.
+			If the post causes a task to wake force a context switch if the woken task
+			has a higher priority than the task we have interrupted. */
+			cChar = SBUF;
+			RI = 0;
+
+			xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
+		}
+
+		if( TI ) 
+		{
+			if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == ( portBASE_TYPE ) pdTRUE )
+			{
+				/* Send the next character queued for Tx. */
+				SBUF = cChar;
+			}
+			else
+			{
+				/* Queue empty, nothing to send. */
+				uxTxEmpty = pdTRUE;
+			}
+
+			TI = 0;
+		}
+	
+		if( xHigherPriorityTaskWoken )
+		{
+			portYIELD();
+		}
+	}
+	portEXIT_CRITICAL();
+}
+/*-----------------------------------------------------------*/
+
+portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
+{
+	/* There is only one port 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 ( portBASE_TYPE ) pdTRUE;
+	}
+	else
+	{
+		return ( portBASE_TYPE ) pdFALSE;
+	}
+}
+/*-----------------------------------------------------------*/
+
+portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
+{
+portBASE_TYPE xReturn;
+
+	/* There is only one port supported. */
+	( void ) pxPort;
+
+	portENTER_CRITICAL();
+	{
+		if( uxTxEmpty == pdTRUE )
+		{
+			SBUF = cOutChar;
+			uxTxEmpty = pdFALSE;
+			xReturn = ( portBASE_TYPE ) pdTRUE;
+		}
+		else
+		{
+			xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
+
+			if( xReturn == ( portBASE_TYPE ) pdFALSE )
+			{
+				xReturn = ( portBASE_TYPE ) pdTRUE;
+			}
+		}
+	}
+	portEXIT_CRITICAL();
+
+	return xReturn;
+}
+/*-----------------------------------------------------------*/
+
+void vSerialClose( xComPortHandle xPort )
+{
+	/* Not implemented in this port. */
+	( void ) xPort;
+}
+/*-----------------------------------------------------------*/
+
+
+
+
+