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

The serial port connection for stm32f4discovery board

Posted by yuanbinzhou on July 8, 2015

Hi!I am new to FreeRTOS,and recently I run FreeRTOS on STM32F4Discovery board,but I found that it is hard to use serial port since there are too many uart pins on this board,so My questions is that how can I successfully connect the "usb to ttl" board to Discovery board(You know that B6/B7,A8/A9 all stands for USART1). IN addition, I change the value of "HSE_VALUE" to 8000000 since the frequency of external crystal is 8MHz.

Another questions is that whether the tickless idle mode is suitable for STM32F4discovery board. Any demos afford?


The serial port connection for stm32f4discovery board

Posted by rtel on July 8, 2015

[Most of your question is not related to FreeRTOS, so would be better posted to an STM32 forum]

The default tickless idle mode can be used on any Cortex-M3/4/7 part, but the power saving it can achieve is limited by two things:

1) The SysTick clock is only 24-bits, and runs very quickly - and therefore overflows often. That limits the maximum tickless period that can be achieved.

2) You cannot enter a very low power state because the really low power modes with stop the SysTick.

Therefore for optimal power saving you will need to create a target specific implementation, such as the one found on the following link:

http://www.freertos.org/STM32L-discovery-low-power-tickless-RTOS-demo.html


[ 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