/* FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 Richard Barry. This file is part of the FreeRTOS.org distribution. FreeRTOS.org 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.org 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.org; 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.org, 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. *************************************************************************** *************************************************************************** * * * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation * * * * This is a concise, step by step, 'hands on' guide that describes both * * general multitasking concepts and FreeRTOS specifics. It presents and * * explains numerous examples that are written using the FreeRTOS API. * * Full source code for all the examples is provided in an accompanying * * .zip file. * * * *************************************************************************** *************************************************************************** Please ensure to read the configuration and relevant port sections of the online documentation. http://www.FreeRTOS.org - Documentation, latest information, license and contact details. http://www.SafeRTOS.com - A version that is certified for use in safety critical systems. http://www.OpenRTOS.com - Commercial support, development, porting, licensing and training services. */ /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0. */ /* Standard includes. */ #include /* Scheduler includes. */ #include "FreeRTOS.h" #include "queue.h" /* Demo application includes. */ #include "serial.h" /* Atmel library includes. */ #include #include #include /*-----------------------------------------------------------*/ /* Location of the COM0 registers. */ #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 ) /* Interrupt control macros. */ #define serINTERRUPT_LEVEL ( 5 ) #define vInterruptOn() serCOM0->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY ) #define vInterruptOff() serCOM0->US_IDR = 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; /*-----------------------------------------------------------*/ /* The interrupt service routine. */ __arm void vSerialISR( void ); /*-----------------------------------------------------------*/ /* * See the serial2.h header file. */ xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength ) { xComPortHandle xReturn = serHANDLE; /* 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 ) ) { PMC_EnablePeripheral( AT91C_ID_US0 ); portENTER_CRITICAL(); { USART_Configure( serCOM0, ( AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE ), ulWantedBaud, configCPU_CLOCK_HZ ); /* Enable Rx and Tx. */ USART_SetTransmitterEnabled( serCOM0, pdTRUE ); USART_SetReceiverEnabled( serCOM0, pdTRUE ); /* Enable the Rx interrupts. The Tx interrupts are not enabled until there are characters to be transmitted. */ serCOM0->US_IER = AT91C_US_RXRDY; /* Enable the interrupts in the AIC. */ AIC_ConfigureIT( AT91C_ID_US0, AT91C_AIC_PRIOR_LOWEST, ( void (*)( void ) ) vSerialISR ); AIC_EnableIT( 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 ) { /* Just to remove compiler warning. */ ( void ) pxPort; /* 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. */ ( void ) xPort; } /*-----------------------------------------------------------*/ /* 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 xHigherPriorityTaskWoken = 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, &xHigherPriorityTaskWoken ) == 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; xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken ); } /* 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( xHigherPriorityTaskWoken ); /* End the interrupt in the AIC. */ AT91C_BASE_AIC->AIC_EOICR = 0; }