| /* | |
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| */ | |
| /* | |
| BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0. | |
| Note this driver is used to test the FreeRTOS port. It is NOT intended to | |
| be an example of an efficient implementation! | |
| */ | |
| /* Standard includes. */ | |
| #include <stdlib.h> | |
| /* Scheduler includes. */ | |
| #include "FreeRTOS.h" | |
| #include "queue.h" | |
| #include "task.h" | |
| /* Demo application includes. */ | |
| #include "serial.h" | |
| /*-----------------------------------------------------------*/ | |
| /* Constants to setup and access the UART. */ | |
| #define serDLAB ( ( unsigned char ) 0x80 ) | |
| #define serENABLE_INTERRUPTS ( ( unsigned char ) 0x03 ) | |
| #define serNO_PARITY ( ( unsigned char ) 0x00 ) | |
| #define ser1_STOP_BIT ( ( unsigned char ) 0x00 ) | |
| #define ser8_BIT_CHARS ( ( unsigned char ) 0x03 ) | |
| #define serFIFO_ON ( ( unsigned char ) 0x01 ) | |
| #define serCLEAR_FIFO ( ( unsigned char ) 0x06 ) | |
| #define serWANTED_CLOCK_SCALING ( ( unsigned long ) 16 ) | |
| /* Constants to setup and access the VIC. */ | |
| #define serU1VIC_CHANNEL ( ( unsigned long ) 0x0007 ) | |
| #define serU1VIC_CHANNEL_BIT ( ( unsigned long ) 0x0080 ) | |
| #define serU1VIC_ENABLE ( ( unsigned long ) 0x0020 ) | |
| /* Misc. */ | |
| #define serINVALID_QUEUE ( ( QueueHandle_t ) 0 ) | |
| #define serHANDLE ( ( xComPortHandle ) 1 ) | |
| #define serNO_BLOCK ( ( TickType_t ) 0 ) | |
| /* Constant to access the VIC. */ | |
| #define serCLEAR_VIC_INTERRUPT ( ( unsigned long ) 0 ) | |
| /* Constants to determine the ISR source. */ | |
| #define serSOURCE_THRE ( ( unsigned char ) 0x02 ) | |
| #define serSOURCE_RX_TIMEOUT ( ( unsigned char ) 0x0c ) | |
| #define serSOURCE_ERROR ( ( unsigned char ) 0x06 ) | |
| #define serSOURCE_RX ( ( unsigned char ) 0x04 ) | |
| #define serINTERRUPT_SOURCE_MASK ( ( unsigned char ) 0x0f ) | |
| #define serINTERRUPT_IS_PENDING ( ( unsigned char ) 0x01 ) | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * The asm wrapper for the interrupt service routine. | |
| */ | |
| extern void vUART_ISREntry( void ); | |
| /* | |
| * The C function called from the asm wrapper. | |
| */ | |
| void vUART_ISRHandler( void ); | |
| /*-----------------------------------------------------------*/ | |
| /* Queues used to hold received characters, and characters waiting to be | |
| transmitted. */ | |
| static QueueHandle_t xRxedChars; | |
| static QueueHandle_t xCharsForTx; | |
| /* Communication flag between the interrupt service routine and serial API. */ | |
| static volatile long lTHREEmpty; | |
| /*-----------------------------------------------------------*/ | |
| xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength ) | |
| { | |
| unsigned long ulDivisor, ulWantedClock; | |
| xComPortHandle xReturn = serHANDLE; | |
| /* Create the queues used to hold Rx and Tx characters. */ | |
| xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) ); | |
| xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) ); | |
| /* Initialise the THRE empty flag. */ | |
| lTHREEmpty = pdTRUE; | |
| if( | |
| ( xRxedChars != serINVALID_QUEUE ) && | |
| ( xCharsForTx != serINVALID_QUEUE ) && | |
| ( ulWantedBaud != ( unsigned long ) 0 ) | |
| ) | |
| { | |
| portENTER_CRITICAL() | |
| { | |
| /* Setup the baud rate: Calculate the divisor value. */ | |
| ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING; | |
| ulDivisor = configCPU_CLOCK_HZ / ulWantedClock; | |
| /* Set the DLAB bit so we can access the divisor. */ | |
| U1LCR |= serDLAB; | |
| /* Setup the divisor. */ | |
| U1DLL = ( unsigned char ) ( ulDivisor & ( unsigned long ) 0xff ); | |
| ulDivisor >>= 8; | |
| U1DLM = ( unsigned char ) ( ulDivisor & ( unsigned long ) 0xff ); | |
| /* Turn on the FIFO's and clear the buffers. */ | |
| U1FCR = ( serFIFO_ON | serCLEAR_FIFO ); | |
| /* Setup transmission format. */ | |
| U1LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS; | |
| /* Setup the VIC for the UART. */ | |
| VICIntSelect &= ~( serU1VIC_CHANNEL_BIT ); | |
| VICIntEnable |= serU1VIC_CHANNEL_BIT; | |
| VICVectAddr1 = ( unsigned long ) vUART_ISREntry; | |
| VICVectCntl1 = serU1VIC_CHANNEL | serU1VIC_ENABLE; | |
| /* Enable UART0 interrupts. */ | |
| U1IER |= serENABLE_INTERRUPTS; | |
| } | |
| portEXIT_CRITICAL(); | |
| } | |
| else | |
| { | |
| xReturn = ( xComPortHandle ) 0; | |
| } | |
| return xReturn; | |
| } | |
| /*-----------------------------------------------------------*/ | |
| signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime ) | |
| { | |
| /* The port handle is not required as this driver only supports UART0. */ | |
| ( 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 char * const pcString, unsigned short usStringLength ) | |
| { | |
| signed char *pxNext; | |
| /* 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; | |
| ( void ) usStringLength; | |
| /* Send each character in the string, one at a time. */ | |
| pxNext = ( signed char * ) pcString; | |
| while( *pxNext ) | |
| { | |
| xSerialPutChar( pxPort, *pxNext, serNO_BLOCK ); | |
| pxNext++; | |
| } | |
| } | |
| /*-----------------------------------------------------------*/ | |
| signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime ) | |
| { | |
| signed portBASE_TYPE xReturn; | |
| /* The port handle is not required as this driver only supports UART0. */ | |
| ( void ) pxPort; | |
| portENTER_CRITICAL(); | |
| { | |
| /* Is there space to write directly to the UART? */ | |
| if( lTHREEmpty == ( long ) pdTRUE ) | |
| { | |
| /* We wrote the character directly to the UART, so was | |
| successful. */ | |
| lTHREEmpty = pdFALSE; | |
| U1THR = cOutChar; | |
| xReturn = pdPASS; | |
| } | |
| else | |
| { | |
| /* We cannot write directly to the UART, so queue the character. | |
| Block for a maximum of xBlockTime if there is no space in the | |
| queue. It is ok to block within a critical section as each | |
| task has it's own critical section management. */ | |
| xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime ); | |
| /* Depending on queue sizing and task prioritisation: While we | |
| were blocked waiting to post interrupts were not disabled. It is | |
| possible that the serial ISR has emptied the Tx queue, in which | |
| case we need to start the Tx off again. */ | |
| if( lTHREEmpty == ( long ) pdTRUE ) | |
| { | |
| xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK ); | |
| lTHREEmpty = pdFALSE; | |
| U1THR = cOutChar; | |
| } | |
| } | |
| } | |
| portEXIT_CRITICAL(); | |
| return xReturn; | |
| } | |
| /*-----------------------------------------------------------*/ | |
| void vUART_ISRHandler( void ) | |
| { | |
| signed char cChar; | |
| portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE; | |
| unsigned char ucInterrupt; | |
| ucInterrupt = U1IIR; | |
| /* The interrupt pending bit is active low. */ | |
| while( ( ucInterrupt & serINTERRUPT_IS_PENDING ) == 0 ) | |
| { | |
| /* What caused the interrupt? */ | |
| switch( ucInterrupt & serINTERRUPT_SOURCE_MASK ) | |
| { | |
| case serSOURCE_ERROR : /* Not handling this, but clear the interrupt. */ | |
| cChar = U1LSR; | |
| break; | |
| case serSOURCE_THRE : /* The THRE is empty. If there is another | |
| character in the Tx queue, send it now. */ | |
| if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE ) | |
| { | |
| U1THR = cChar; | |
| } | |
| else | |
| { | |
| /* There are no further characters | |
| queued to send so we can indicate | |
| that the THRE is available. */ | |
| lTHREEmpty = pdTRUE; | |
| } | |
| break; | |
| case serSOURCE_RX_TIMEOUT : | |
| case serSOURCE_RX : /* A character was received. Place it in | |
| the queue of received characters. */ | |
| cChar = U1RBR; | |
| xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken ); | |
| break; | |
| default : /* There is nothing to do, leave the ISR. */ | |
| break; | |
| } | |
| ucInterrupt = U1IIR; | |
| } | |
| /* Clear the ISR in the VIC. */ | |
| VICVectAddr = serCLEAR_VIC_INTERRUPT; | |
| /* Exit the ISR. If a task was woken by either a character being received | |
| or transmitted then a context switch will occur. */ | |
| portEXIT_SWITCHING_ISR( xHigherPriorityTaskWoken ); | |
| } | |
| /*-----------------------------------------------------------*/ | |