/* FreeRTOS V8.0.1 - Copyright (C) 2014 Real Time Engineers Ltd. All rights reserved VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION. *************************************************************************** * * * FreeRTOS provides completely free yet professionally developed, * * robust, strictly quality controlled, supported, and cross * * platform software that has become a de facto standard. * * * * Help yourself get started quickly and support the FreeRTOS * * project by purchasing a FreeRTOS tutorial book, reference * * manual, or both from: http://www.FreeRTOS.org/Documentation * * * * Thank you! * * * *************************************************************************** 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. >>! NOTE: The modification to the GPL is included to allow you to !<< >>! distribute a combined work that includes FreeRTOS without being !<< >>! obliged to provide the source code for proprietary components !<< >>! outside of the FreeRTOS kernel. !<< 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. Full license text is available from the following link: http://www.freertos.org/a00114.html 1 tab == 4 spaces! *************************************************************************** * * * Having a problem? Start by reading the FAQ "My application does * * not run, what could be wrong?" * * * * http://www.FreeRTOS.org/FAQHelp.html * * * *************************************************************************** http://www.FreeRTOS.org - Documentation, books, training, latest versions, license and Real Time Engineers Ltd. contact details. http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products, including FreeRTOS+Trace - an indispensable productivity tool, a DOS compatible FAT file system, and our tiny thread aware UDP/IP stack. http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS licenses offer ticketed support, indemnification and middleware. http://www.SafeRTOS.com - High Integrity Systems also provide a safety engineered and independently SIL3 certified version for use in safety and mission critical applications that require provable dependability. 1 tab == 4 spaces! */ /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. * * This is not a proper UART driver. It only supports one port, uses loopback * mode, and is used to test interrupts that use the FreeRTOS API as part of * a wider test suite. Nor is it intended to show an efficient implementation * of a UART interrupt service routine as queues are used to pass individual * characters one at a time! */ /* Standard includes. */ #include /* Scheduler includes. */ #include "FreeRTOS.h" #include "queue.h" #include "task.h" /* Demo application includes. */ #include "serial.h" /* Misc. constants. */ #define serNO_BLOCK ( ( TickType_t ) 0 ) /* The queue used to hold received characters. */ static QueueHandle_t xRxedChars; /* The queue used to hold characters waiting transmission. */ static QueueHandle_t xCharsForTx; /*-----------------------------------------------------------*/ xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength ) { unsigned long ulBaudRateCount; /* Initialise the hardware. */ /* Generate the baud rate constants for the wanted baud rate. */ ulBaudRateCount = configCPU_CLOCK_HZ / ulWantedBaud; portENTER_CRITICAL(); { /* Create the queues used by the com test task. */ xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) ); xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) ); /* Reset UART. */ UCA1CTL1 |= UCSWRST; /* Use SMCLK. */ UCA1CTL1 = UCSSEL0 | UCSSEL1; /* Setup baud rate low byte. */ UCA1BR0 = ( unsigned char ) ( ulBaudRateCount & ( unsigned long ) 0xff ); /* Setup baud rate high byte. */ ulBaudRateCount >>= 8UL; UCA1BR1 = ( unsigned char ) ( ulBaudRateCount & ( unsigned long ) 0xff ); /* UCLISTEN sets loopback mode! */ UCA1STAT = UCLISTEN; /* Enable interrupts. */ UCA1IE |= UCRXIE; /* Take out of reset. */ UCA1CTL1 &= ~UCSWRST; } portEXIT_CRITICAL(); /* Note the comments at the top of this file about this not being a generic UART driver. */ return NULL; } /*-----------------------------------------------------------*/ signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime ) { /* 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 char cOutChar, TickType_t xBlockTime ) { signed portBASE_TYPE xReturn; /* Send the next character to the queue of characters waiting transmission, then enable the UART Tx interrupt, just in case UART transmission has already completed and switched itself off. */ xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime ); UCA1IE |= UCTXIE; return xReturn; } /*-----------------------------------------------------------*/ /* The implementation of this interrupt is provided to demonstrate the use of queues from inside an interrupt service routine. It is *not* intended to be an efficient interrupt implementation. A real application should make use of the DMA. Or, as a minimum, transmission and reception could use a simple RAM ring buffer, and synchronise with a task using a semaphore when a complete message has been received or transmitted. */ #pragma vector=USCI_A1_VECTOR static __interrupt void prvUSCI_A1_ISR( void ) { signed char cChar; portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE; while( ( UCA1IFG & UCRXIFG ) != 0 ) { /* Get the character from the UART and post it on the queue of Rxed characters. */ cChar = UCA1RXBUF; xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken ); } /* If there is a Tx interrupt pending and the tx interrupts are enabled. */ if( ( UCA1IFG & UCTXIFG ) != 0 ) { /* The previous character has been transmitted. See if there are any further characters waiting transmission. */ if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE ) { /* There was another character queued - transmit it now. */ UCA1TXBUF = cChar; } else { /* There were no other characters to transmit - disable the Tx interrupt. */ UCA1IE &= ~UCTXIE; } } __bic_SR_register_on_exit( SCG1 + SCG0 + OSCOFF + CPUOFF ); /* If writing to a queue caused a task to unblock, and the unblocked task has a priority equal to or above the task that this interrupt interrupted, then lHigherPriorityTaskWoken will have been set to pdTRUE internally within xQueuesendFromISR(), and portEND_SWITCHING_ISR() will ensure that this interrupt returns directly to the higher priority unblocked task. THIS MUST BE THE LAST THING DONE IN THE ISR. */ portYIELD_FROM_ISR( xHigherPriorityTaskWoken ); }