www.pudn.com > FreeRTOSV4.0.0.zip > serial.c, change:2006-03-21,size:8616b


/* 
	FreeRTOS V4.0.0 - Copyright (C) 2003-2006 Richard Barry. 
 
	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 as published by 
	the Free Software Foundation; either version 2 of the License, or 
	(at your option) any later version. 
 
	FreeRTOS is distributed in the hope that it will be useful, 
	but WITHOUT ANY WARRANTY; without even the implied warranty of 
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
	GNU General Public License for more details. 
 
	You should have received a copy of the GNU General Public License 
	along with FreeRTOS; if not, write to the Free Software 
	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 
	A special exception to the GPL can be applied should you wish to distribute 
	a combined work that includes FreeRTOS, without being obliged to provide 
	the source code for any proprietary components.  See the licensing section  
	of http://www.FreeRTOS.org for full details of how and when the exception 
	can be applied. 
 
	*************************************************************************** 
	See http://www.FreeRTOS.org for documentation, latest information, license  
	and contact details.  Please ensure to read the configuration and relevant  
	port sections of the online documentation. 
	*************************************************************************** 
*/ 
 
/*  
	BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.  
*/ 
 
/* Standard includes. */  
#include <stdlib.h> 
 
/* Scheduler includes. */ 
#include "FreeRTOS.h" 
#include "queue.h" 
 
/* Demo application includes. */ 
#include "serial.h" 
 
/*-----------------------------------------------------------*/ 
 
/* Location of the COM0 registers. */ 
#define serCOM0							( ( AT91PS_USART ) AT91C_BASE_US0 ) 
 
/* Interrupt control macros. */ 
#define serINTERRUPT_LEVEL				( 5 ) 
#define vInterruptOn()					AT91F_US_EnableIt( serCOM0, AT91C_US_TXRDY | AT91C_US_RXRDY ) 
#define vInterruptOff()					AT91F_US_DisableIt( serCOM0, AT91C_US_TXRDY ) 
 
/* Misc constants. */ 
#define serINVALID_QUEUE				( ( xQueueHandle ) 0 ) 
#define serHANDLE						( ( xComPortHandle ) 1 ) 
#define serNO_BLOCK						( ( portTickType ) 0 ) 
#define serNO_TIMEGUARD					( ( unsigned portLONG ) 0 ) 
#define serNO_PERIPHERAL_B_SETUP		( ( unsigned portLONG ) 0 ) 
 
 
/* Queues used to hold received characters, and characters waiting to be 
transmitted. */ 
static xQueueHandle xRxedChars;  
static xQueueHandle xCharsForTx;  
 
/*-----------------------------------------------------------*/ 
 
/* Interrupt entry point written in the assembler file serialISR.s79. */ 
extern void vSerialISREntry( void ); 
 
/* The interrupt service routine - called from the assembly entry point. */ 
__arm void vSerialISR( void ); 
 
/*-----------------------------------------------------------*/ 
 
/* 
 * See the serial2.h header file. 
 */ 
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength ) 
{ 
xComPortHandle xReturn = serHANDLE; 
extern void ( vUART_ISR )( void ); 
 
	/* Create the queues used to hold Rx and Tx characters. */ 
	xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) ); 
	xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) ); 
 
	/* If the queues were created correctly then setup the serial port  
	hardware. */ 
	if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) ) 
	{ 
		portENTER_CRITICAL(); 
		{ 
			/* Enable the USART clock. */ 
   			AT91F_PMC_EnablePeriphClock( AT91C_BASE_PMC, 1 << AT91C_ID_US0 ); 
 
			AT91F_PIO_CfgPeriph( AT91C_BASE_PIOA, ( ( unsigned portLONG ) AT91C_PA5_RXD0 ) | ( ( unsigned portLONG ) AT91C_PA6_TXD0 ), serNO_PERIPHERAL_B_SETUP ); 
 
			/* Set the required protocol. */ 
			AT91F_US_Configure( serCOM0, configCPU_CLOCK_HZ, AT91C_US_ASYNC_MODE, ulWantedBaud, serNO_TIMEGUARD ); 
 
			/* Enable Rx and Tx. */ 
			serCOM0->US_CR = AT91C_US_RXEN | AT91C_US_TXEN; 
 
			/* Enable the Rx interrupts.  The Tx interrupts are not enabled 
			until there are characters to be transmitted. */ 
    		AT91F_US_EnableIt( serCOM0, AT91C_US_RXRDY ); 
 
			/* Enable the interrupts in the AIC. */ 
			AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_US0, serINTERRUPT_LEVEL, AT91C_AIC_SRCTYPE_INT_LEVEL_SENSITIVE, ( void (*)( void ) ) vSerialISREntry ); 
			AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_US0 ); 
		} 
		portEXIT_CRITICAL(); 
	} 
	else 
	{ 
		xReturn = ( xComPortHandle ) 0; 
	} 
 
	/* This demo file only supports a single port but we have to return  
	something to comply with the standard demo header file. */ 
	return xReturn; 
} 
/*-----------------------------------------------------------*/ 
 
signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime ) 
{ 
	/* The port handle is not required as this driver only supports one port. */ 
	( 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; 
	} 
} 
/*-----------------------------------------------------------*/ 
 
void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength ) 
{ 
signed portCHAR *pxNext; 
 
	/* A couple of parameters that this port does not use. */ 
	( void ) usStringLength; 
	( void ) pxPort; 
 
	/* NOTE: This implementation does not handle the queue being full as no 
	block time is used! */ 
 
	/* The port handle is not required as this driver only supports UART0. */ 
	( void ) pxPort; 
 
	/* Send each character in the string, one at a time. */ 
	pxNext = ( signed portCHAR * ) pcString; 
	while( *pxNext ) 
	{ 
		xSerialPutChar( pxPort, *pxNext, serNO_BLOCK ); 
		pxNext++; 
	} 
} 
/*-----------------------------------------------------------*/ 
 
signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime ) 
{ 
	/* Place the character in the queue of characters to be transmitted. */ 
	if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS ) 
	{ 
		return pdFAIL; 
	} 
 
	/* Turn on the Tx interrupt so the ISR will remove the character from the 
	queue and send it.   This does not need to be in a critical section as 
	if the interrupt has already removed the character the next interrupt 
	will simply turn off the Tx interrupt again. */ 
	vInterruptOn(); 
 
	return pdPASS; 
} 
/*-----------------------------------------------------------*/ 
 
void vSerialClose( xComPortHandle xPort ) 
{ 
	/* Not supported as not required by the demo application. */ 
} 
/*-----------------------------------------------------------*/ 
 
/* Serial port ISR.  This can cause a context switch so is not defined as a 
standard ISR using the __irq keyword.  Instead a wrapper function is defined 
within serialISR.s79 which in turn calls this function.  See the port 
documentation on the FreeRTOS.org website for more information. */ 
__arm void vSerialISR( void ) 
{ 
unsigned portLONG ulStatus; 
signed portCHAR cChar; 
portBASE_TYPE xTaskWokenByTx = pdFALSE, xTaskWokenByPost = pdFALSE; 
 
	/* What caused the interrupt? */ 
	ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR; 
 
	if( ulStatus & AT91C_US_TXRDY ) 
	{ 
		/* The interrupt was caused by the THR becoming empty.  Are there any 
		more characters to transmit? */ 
		if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xTaskWokenByTx ) == pdTRUE ) 
		{ 
			/* A character was retrieved from the queue so can be sent to the 
			THR now. */ 
			serCOM0->US_THR = cChar; 
		} 
		else 
		{ 
			/* Queue empty, nothing to send so turn off the Tx interrupt. */ 
			vInterruptOff(); 
		}		 
	} 
 
	if( ulStatus & AT91C_US_RXRDY ) 
	{ 
		/* The interrupt was caused by a character being received.  Grab the 
		character from the RHR and place it in the queue or received  
		characters. */ 
		cChar = serCOM0->US_RHR; 
		xTaskWokenByPost = xQueueSendFromISR( xRxedChars, &cChar, xTaskWokenByPost ); 
	} 
 
	/* If a task was woken by either a character being received or a character  
	being transmitted then we may need to switch to another task. */ 
	portEND_SWITCHING_ISR( ( xTaskWokenByPost || xTaskWokenByTx ) ); 
 
	/* End the interrupt in the AIC. */ 
	AT91C_BASE_AIC->AIC_EOICR = 0; 
}