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*/ | |
/* | |
BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR USART1. | |
***Note*** This example uses queues to send each character into an interrupt | |
service routine and out of an interrupt service routine individually. This | |
is done to demonstrate queues being used in an interrupt, and to deliberately | |
load the system to test the FreeRTOS port. It is *NOT* meant to be an | |
example of an efficient implementation. An efficient implementation should | |
use FIFO's or DMA if available, and only use FreeRTOS API functions when | |
enough has been received to warrant a task being unblocked to process the | |
data. | |
*/ | |
/* Scheduler includes. */ | |
#include "FreeRTOS.h" | |
#include "queue.h" | |
#include "semphr.h" | |
#include "comtest2.h" | |
/* Library includes. */ | |
#include "asf.h" | |
/* Demo application includes. */ | |
#include "demo_serial.h" | |
/*-----------------------------------------------------------*/ | |
/* Misc defines. */ | |
#define serINVALID_QUEUE ( ( QueueHandle_t ) 0 ) | |
#define serNO_BLOCK ( ( TickType_t ) 0 ) | |
#define serPMC_USART_ID ( BOARD_ID_USART ) | |
/* The USART supported by this file. */ | |
#define serUSART_PORT ( USART1 ) | |
#define serUSART_IRQ ( USART1_IRQn ) | |
/* Every bit in the interrupt mask. */ | |
#define serMASK_ALL_INTERRUPTS ( 0xffffffffUL ) | |
/*-----------------------------------------------------------*/ | |
/* The queue used to hold received characters. */ | |
static QueueHandle_t xRxedChars; | |
static QueueHandle_t xCharsForTx; | |
/*-----------------------------------------------------------*/ | |
/* | |
* See the serial.h header file. | |
*/ | |
xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength ) | |
{ | |
uint32_t ulChar; | |
xComPortHandle xReturn; | |
const sam_usart_opt_t xUSARTSettings = | |
{ | |
ulWantedBaud, | |
US_MR_CHRL_8_BIT, | |
US_MR_PAR_NO, | |
US_MR_NBSTOP_1_BIT, | |
US_MR_CHMODE_NORMAL, | |
0 /* Only used in IrDA mode. */ | |
}; | |
/* Create the queues used to hold Rx/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 ) ) | |
{ | |
/* Enable the peripheral clock in the PMC. */ | |
pmc_enable_periph_clk( serPMC_USART_ID ); | |
/* Configure USART in serial mode. */ | |
usart_init_rs232( serUSART_PORT, &xUSARTSettings, sysclk_get_cpu_hz() ); | |
/* Disable all the interrupts. */ | |
usart_disable_interrupt( serUSART_PORT, serMASK_ALL_INTERRUPTS ); | |
/* Enable the receiver and transmitter. */ | |
usart_enable_tx( serUSART_PORT ); | |
usart_enable_rx( serUSART_PORT ); | |
/* Clear any characters before enabling interrupt. */ | |
usart_getchar( serUSART_PORT, &ulChar ); | |
/* Enable Rx end interrupt. */ | |
usart_enable_interrupt( serUSART_PORT, US_IER_RXRDY ); | |
/* Configure and enable interrupt of USART. */ | |
NVIC_SetPriority( serUSART_IRQ, configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY ); | |
NVIC_EnableIRQ( serUSART_IRQ ); | |
} | |
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 USART1. */ | |
( 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 ) | |
{ | |
signed portBASE_TYPE xReturn; | |
/* This simple example only supports one port. */ | |
( void ) pxPort; | |
if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) == pdPASS ) | |
{ | |
xReturn = pdPASS; | |
usart_enable_interrupt( serUSART_PORT, US_IER_TXRDY ); | |
} | |
else | |
{ | |
xReturn = pdFAIL; | |
} | |
return xReturn; | |
} | |
/*-----------------------------------------------------------*/ | |
void vSerialClose( xComPortHandle xPort ) | |
{ | |
/* Not supported as not required by the demo application. */ | |
( void ) xPort; | |
} | |
/*-----------------------------------------------------------*/ | |
/* | |
* It should be noted that the com test tasks (which use make use of this file) | |
* are included to demonstrate queues being used to communicate between tasks | |
* and interrupts, and to demonstrate a context switch being performed from | |
* inside an interrupt service routine. The serial driver used here is *not* | |
* intended to represent an efficient implementation. Real applications should | |
* make use of the USARTS peripheral DMA channel (PDC). | |
*/ | |
void USART1_Handler( void ) | |
{ | |
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE; | |
uint8_t ucChar; | |
uint32_t ulChar; | |
uint32_t ulUSARTStatus, ulUSARTMask; | |
ulUSARTStatus = usart_get_status( serUSART_PORT ); | |
ulUSARTMask = usart_get_interrupt_mask( serUSART_PORT ); | |
ulUSARTStatus &= ulUSARTMask; | |
if( ( ulUSARTStatus & US_CSR_TXRDY ) != 0UL ) | |
{ | |
/* The interrupt was caused by the TX register becoming empty. Are | |
there any more characters to transmit? */ | |
if( xQueueReceiveFromISR( xCharsForTx, &ucChar, &xHigherPriorityTaskWoken ) == pdTRUE ) | |
{ | |
/* A character was retrieved from the queue so can be sent to the | |
USART now. */ | |
usart_putchar( serUSART_PORT, ( uint32_t ) ucChar ); | |
} | |
else | |
{ | |
usart_disable_interrupt( serUSART_PORT, US_IER_TXRDY ); | |
} | |
} | |
if( ( ulUSARTStatus & US_CSR_RXRDY ) != 0UL ) | |
{ | |
/* A character has been received on the USART, send it to the Rx | |
handler task. */ | |
usart_getchar( serUSART_PORT, &ulChar ); | |
ucChar = ( uint8_t ) ( ulChar & 0xffUL ); | |
xQueueSendFromISR( xRxedChars, &ucChar, &xHigherPriorityTaskWoken ); | |
} | |
/* If sending or receiving from a queue has caused a task to unblock, and | |
the unblocked task has a priority equal to or higher than the currently | |
running task (the task this ISR interrupted), then xHigherPriorityTaskWoken | |
will have automatically been set to pdTRUE within the queue send or receive | |
function. portEND_SWITCHING_ISR() will then ensure that this ISR returns | |
directly to the higher priority unblocked task. */ | |
portEND_SWITCHING_ISR( xHigherPriorityTaskWoken ); | |
} | |