Quality RTOS & Embedded Software

 Real time embedded FreeRTOS RSS feed 
Quick Start Supported MCUs PDF Books Trace Tools Ecosystem


Trying to port to xmega256A3...

Posted by Travis Griggs on November 26, 2012
We have some code where I work at that runs on an xmega256A3. I think it's overtly complex with all of its state machines, and would like to try using FreeRTOS with it. I'm new to this. I've read through a bunch of the docs. I downloaded the latest (I'm excited about the tickless support, because we frequently sleep to save power). And I think I'm correct in noticing that this processor is not an official supported port. I'm developing on an OSX box with CrossPack's AVR toolchain and avrdude.

So I cloned Demo/AVR_ATMega323_WinAVR, that seemed like it would be the most similar to the xmega256a3 and my platform. I made minor adjustments to the makefile (adjusted the DIRAVR and MCU variables).

When I try to 'make' from there, I get the following error:

ParTest/ParTest.c:102:2: error: 'DDRB' undeclared (first use in this function)

What confuses me though, is where DDRB would normally come from? A 'grep -R "DDRB" *' at the root FreeRTOS directory level, doesn't turn up anything that gives me any hints about what to do to resolve it for my target...

Any help/hints with this specific issue, as well as any general guidance about what else I'm going to need to do to make this work, are much appreciated. I would love to hear that there's already been a port to the xmega256a3...

RE: Trying to port to xmega256A3...

Posted by MEdwards on November 26, 2012
I just looked in partest.c (the file that generates the error) for the AVR GCC port and it contains the line:


FreeRTOSConfig.h includes so the definition must come from there.

I guess that is a data direction register for port B? I suspect the name used by the compiler has changed since the demo was written.

You will find other AVR ports in the Interactive site http://interactive.freertos.org/forums/103473-atmel. Also check out the forums at
where there are some FreeRTOS users.

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

Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.

Latest News

NXP tweet showing LPC5500 (ARMv8-M Cortex-M33) running FreeRTOS.

Meet Richard Barry and learn about running FreeRTOS on RISC-V at FOSDEM 2019

Version 10.1.1 of the FreeRTOS kernel is available for immediate download. MIT licensed.

View a recording of the "OTA Update Security and Reliability" webinar, presented by TI and AWS.


FreeRTOS and other embedded software careers at AWS.

FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

Espressif ESP32

IAR Partner

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers


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

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

OpenRTOS and SafeRTOS

Xilinx Microblaze and Zynq partner