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


Hazards of sleep mode

Posted by Michael on March 12, 2010
I wrote an an idle hook shown here
void vApplicationIdleHook( void )
P1OUT &= ~0x01;//go to sleep lights off!
LPM3;// LPM Mode - remove to make debug a little easier...

That should cause the LED to turn off, and MSP430 to go to sleep when there is nothing to do. I turn the LED on during some tasks.

I also made sure to modify the sleep mode bit in the SR upon exit of any interrupt that could possibly wake the MCU (with the exception of the scheduler tick isr in port. The macro in iar is
__bic_SR_register_on_exit(LPM3_bits);   // Exit Interrupt as active CPU 

However, it seems as though putting the MCU to sleep causes some irregular behavior. The led stays on always, although when i scope it, it will turn off for a couple instructions cycles when ever i wake the mcu via one of the interrupts (UART).
If I comment out the LPM3 instruction, things go as planned. THe led stays off for most of the time and only comes on when a task is running.

I am using a MSP4f305438

Any ideas?

RE: Hazards of sleep mode

Posted by Richard on March 13, 2010
Maybe not much help - but I seem to recall adding a wake from low power mode into the MPS430 tick handler code some time back (search http://www.freertos.org/History.txt to find the version this first went into). I can't remember which low power mode was used, but I know not all were suitable.


RE: Hazards of sleep mode

Posted by Michael on March 14, 2010
Hey Richard, that thought occurred to me yesterday as well. I am using version 5.4 right now. I will give that a try and post my results when i have something.


[ 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