mirror of
https://github.com/FreeRTOS/FreeRTOS-Kernel.git
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219 lines
6.6 KiB
C
219 lines
6.6 KiB
C
/*
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FreeRTOS.org V4.6.1 - Copyright (C) 2003-2007 Richard Barry.
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This file is part of the FreeRTOS.org distribution.
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FreeRTOS.org is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FreeRTOS.org is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FreeRTOS.org; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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A special exception to the GPL can be applied should you wish to distribute
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a combined work that includes FreeRTOS.org, without being obliged to provide
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the source code for any proprietary components. See the licensing section
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of http://www.FreeRTOS.org for full details of how and when the exception
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can be applied.
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***************************************************************************
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See http://www.FreeRTOS.org for documentation, latest information, license
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and contact details. Please ensure to read the configuration and relevant
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port sections of the online documentation.
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Also see http://www.SafeRTOS.com a version that has been certified for use
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in safety critical systems, plus commercial licensing, development and
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support options.
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***************************************************************************
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*/
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/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.
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*
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* This file only supports UART 1
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*/
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/* Standard includes. */
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#include <stdlib.h>
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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#include "queue.h"
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#include "task.h"
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/* Demo application includes. */
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#include "serial.h"
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/* The queue used to hold received characters. */
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static xQueueHandle xRxedChars;
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/* The queue used to hold characters waiting transmission. */
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static xQueueHandle xCharsForTx;
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static volatile portSHORT sTHREEmpty;
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static volatile portSHORT queueFail = pdFALSE;
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/*-----------------------------------------------------------*/
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xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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{
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/* Initialise the hardware. */
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portENTER_CRITICAL();
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{
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/* Create the queues used by the com test task. */
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xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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if ( xRxedChars == 0)
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{
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queueFail = pdTRUE;
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}
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if ( xCharsForTx == 0)
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{
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queueFail = pdTRUE;
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}
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/* Initialize UART asynchronous mode */
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BGR0 = configCLKP1_CLOCK_HZ / ulWantedBaud;
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SCR0 = 0x17; /* 8N1 */
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SMR0 = 0x0d; /* enable SOT3, Reset, normal mode */
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SSR0 = 0x02; /* LSB first, enable receive interrupts */
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PIER08_IE2 = 1; /* enable input */
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DDR08_D2 = 0; /* switch P08_2 to input */
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DDR08_D3 = 1; /* switch P08_3 to output */
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}
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portEXIT_CRITICAL();
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/* Unlike other ports, this serial code does not allow for more than one
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com port. We therefore don't return a pointer to a port structure and can
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instead just return NULL. */
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return NULL;
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}
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/*-----------------------------------------------------------*/
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signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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{
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/* Get the next character from the buffer. Return false if no characters
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are available, or arrive before xBlockTime expires. */
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if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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{
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return pdTRUE;
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}
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else
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{
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return pdFALSE;
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}
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}
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/*-----------------------------------------------------------*/
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signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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{
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signed portBASE_TYPE xReturn;
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/* Transmit a character. */
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portENTER_CRITICAL();
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{
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if( sTHREEmpty == pdTRUE )
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{
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/* If sTHREEmpty is true then the UART Tx ISR has indicated that
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there are no characters queued to be transmitted - so we can
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write the character directly to the shift Tx register. */
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sTHREEmpty = pdFALSE;
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TDR0 = cOutChar;
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xReturn = pdPASS;
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}
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else
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{
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/* sTHREEmpty is false, so there are still characters waiting to be
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transmitted. We have to queue this character so it gets
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transmitted in turn. */
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/* Return false if after the block time there is no room on the Tx
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queue. It is ok to block inside a critical section as each task
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maintains it's own critical section status. */
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if (xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) == pdTRUE)
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{
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xReturn = pdPASS;
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}
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else
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{
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xReturn = pdFAIL;
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}
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}
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if (pdPASS == xReturn)
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{
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/* Turn on the Tx interrupt so the ISR will remove the character from the
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queue and send it. This does not need to be in a critical section as
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if the interrupt has already removed the character the next interrupt
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will simply turn off the Tx interrupt again. */
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SSR0_TIE = 1;
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}
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}
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portEXIT_CRITICAL();
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return pdPASS;
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}
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/*-----------------------------------------------------------*/
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/*
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* UART RX interrupt service routine.
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*/
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__interrupt void UART0_RxISR (void)
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{
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volatile signed portCHAR cChar;
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/* Get the character from the UART and post it on the queue of Rxed
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characters. */
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cChar = RDR0;
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if( xQueueGenericSendFromISR( xRxedChars, (const void * const) &cChar, (signed portBASE_TYPE) pdFALSE, (portBASE_TYPE) 0 ) )
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{
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/*If the post causes a task to wake force a context switch
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as the woken task may have a higher priority than the task we have
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interrupted. */
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portYIELDFromISR();
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}
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}
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/*-----------------------------------------------------------*/
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/*
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* UART Tx interrupt service routine.
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*/
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__interrupt void UART0_TxISR (void)
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{
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signed portCHAR cChar;
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signed portBASE_TYPE xTaskWoken;
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/* The previous character has been transmitted. See if there are any
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further characters waiting transmission. */
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if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xTaskWoken ) == pdTRUE )
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{
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/* There was another character queued - transmit it now. */
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TDR0 = cChar;
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}
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else
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{
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/* There were no other characters to transmit. */
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sTHREEmpty = pdTRUE;
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/* Disable transmit interrupts */
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SSR0_TIE = 0;
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}
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}
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