| /* | |
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| */ | |
| /* | |
| 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 ( ( QueueHandle_t ) 0 ) | |
| #define serHANDLE ( ( xComPortHandle ) 1 ) | |
| #define serNO_BLOCK ( ( TickType_t ) 0 ) | |
| #define serNO_TIMEGUARD ( ( unsigned long ) 0 ) | |
| #define serNO_PERIPHERAL_B_SETUP ( ( unsigned long ) 0 ) | |
| /* Queues used to hold received characters, and characters waiting to be | |
| transmitted. */ | |
| static QueueHandle_t xRxedChars; | |
| static QueueHandle_t 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 long 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 char ) ); | |
| xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) ); | |
| /* 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 long ) AT91C_PA5_RXD0 ) | ( ( unsigned long ) 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 char *pcRxedChar, TickType_t 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 char * const pcString, unsigned short usStringLength ) | |
| { | |
| signed char *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 char * ) pcString; | |
| while( *pxNext ) | |
| { | |
| xSerialPutChar( pxPort, *pxNext, serNO_BLOCK ); | |
| pxNext++; | |
| } | |
| } | |
| /*-----------------------------------------------------------*/ | |
| signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t 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 long ulStatus; | |
| signed char 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; | |
| } | |