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




Loading

[STM32F4] Communication betwenn 2 tasks

Posted by Ronan on February 10, 2012
Hi!

I 'm learning to use FreeRTOS and I ask myself a question on the communication between 2 task.

In my example, I realise an analog to digital converter on one pin every 100 ms and I send this resultat in a queue.

An other task receives this information by the queue and transmits it at hyperterminal (via UART) every 500 ms.

The problem is that the transmitted data is not the last sampled data.

What is the solution to communicate when 2 tasks don't work at the same frequency ?

thanks,

Ronan.

RE: [STM32F4] Communication betwenn 2 tasks

Posted by Richard Damon on February 10, 2012
If task2 just wants the "last" value converted, the best choice is for the data source to just put the value in a global variable and the second task to read from that.

The idea of a queue is to allow a task to wait for data, and to startup as soon as it is available, or if the queue gets full, for the generating task to be delayed, and restarted as soon as there is space to place the data.

Both ends of a queue by definition work at the same average rate, otherwise the queue overflows or underflows.


[ 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