Quality RTOS & Embedded Software

 Real time embedded FreeRTOS RSS feed 
Real time embedded FreeRTOS mailing list 
Quick Start Supported MCUs PDF Books Trace Tools Ecosystem TCP & FAT Training

[Co-Routine Specific]

BaseType_t crQUEUE_SEND_FROM_ISR ( QueueHandle_t xQueue, void *pvItemToQueue, BaseType_t xCoRoutinePreviouslyWoken )

crQUEUE_SEND_FROM_ISR() is a macro. The data types are shown in the prototype above for reference only.

The macro's crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() are the co-routine equivalent to the xQueueSendFromISR() and xQueueReceiveFromISR() functions used by tasks.

crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() can only be used to pass data between a co-routine and and ISR, whereas xQueueSendFromISR() and xQueueReceiveFromISR() can only be used to pass data between a task and and ISR.

crQUEUE_SEND_FROM_ISR can only be called from an ISR to send data to a queue that is being used from within a co-routine.

See the co-routine section of the web documentation for information on passing data between tasks and co-routines and between ISR's and co-routines.

xQueue The handle to the queue on which the item is to be posted.
pvItemToQueue A pointer to the item that is to be placed on the queue. The size of the items the queue will hold was defined when the queue was created, so this many bytes will be copied from pvItemToQueue into the queue storage area.
xCoRoutinePreviouslyWoken This is included so an ISR can post onto the same queue multiple times from a single interrupt. The first call should always pass in pdFALSE. Subsequent calls should pass in the value returned from the previous call.
pdTRUE if a co-routine was woken by posting onto the queue. This is used by the ISR to determine if a context switch may be required following the ISR.
Example usage:
 // A co-routine that blocks on a queue waiting for characters to be received.
 static void vReceivingCoRoutine( CoRoutineHandle_t xHandle,
                                  UBaseType_t uxIndex )
 char cRxedChar;
 BaseType_t xResult;

     // All co-routines must start with a call to crSTART().
     crSTART( xHandle );

     for( ;; )
         // Wait for data to become available on the queue.  This assumes the
         // queue xCommsRxQueue has already been created!
         crQUEUE_RECEIVE( xHandle,
                          &xResult );

         // Was a character received?
         if( xResult == pdPASS )
             // Process the character here.

     // All co-routines must end with a call to crEND().

 // An ISR that uses a queue to send characters received on a serial port to
 // a co-routine.
 void vUART_ISR( void )
 char cRxedChar;
 BaseType_t xCRWokenByPost = pdFALSE;

     // We loop around reading characters until there are none left in the UART.
     while( UART_RX_REG_NOT_EMPTY() )
         // Obtain the character from the UART.
         cRxedChar = UART_RX_REG;

         // Post the character onto a queue.  xCRWokenByPost will be pdFALSE
         // the first time around the loop.  If the post causes a co-routine
         // to be woken (unblocked) then xCRWokenByPost will be set to pdTRUE.
         // In this manner we can ensure that if more than one co-routine is
         // blocked on the queue only one is woken by this ISR no matter how
         // many characters are posted to the queue.
         xCRWokenByPost = crQUEUE_SEND_FROM_ISR( xCommsRxQueue,
                                                 xCRWokenByPost );

[ Back to the top ]    [ About FreeRTOS ]    [ Sitemap ]    [ ]

Copyright (C) 2004-2010 Richard Barry. Copyright (C) 2010-2016 Real Time Engineers Ltd.
Any and all data, files, source code, html content and documentation included in the FreeRTOSTM distribution or available on this site are the exclusive property of Real Time Engineers Ltd.. See the files license.txt (included in the distribution) and this copyright notice for more information. FreeRTOSTM and FreeRTOS.orgTM are trade marks of Real Time Engineers Ltd.

Latest News:

FreeRTOS V9.0.0 is now available for download.

Free TCP/IP and file system demos for the RTOS

Sponsored Links

⇓ Now With No Code Size Limit! ⇓
⇑ Free Download Without Registering ⇑

FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

Renesas Electronics Gold Alliance RTOS Partner.jpg

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers

Atmel RTOS partner supporting ARM Cortex-M3 and AVR32 microcontrollers

STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0

Xilinx Microblaze and Zynq partner

Silicon Labs low power RTOS partner

Altera RTOS partner for Nios II and Cortex-A9 SoC

Freescale Alliance RTOS Member supporting ARM and ColdFire microcontrollers

Infineon ARM Cortex-M microcontrollers

Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers

Cypress RTOS partner supporting ARM Cortex-M3

Fujitsu RTOS partner supporting ARM Cortex-M3 and FM3

Microsemi (previously Actel) RTOS partner supporting ARM Cortex-M3

Atollic Partner

IAR Partner

Keil ARM Partner

Embedded Artists