/* | |
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*************************************************************************** | |
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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" | |
/* Atmel library includes. */ | |
#include <usart/usart.h> | |
#include <aic/aic.h> | |
#include <pmc/pmc.h> | |
/*-----------------------------------------------------------*/ | |
/* 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 long ) 0 ) | |
#define serNO_PERIPHERAL_B_SETUP ( ( unsigned long ) 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 long 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 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 ) ) | |
{ | |
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 char *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 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, 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 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; | |
} | |