Hi, I am a beginner for RTOS and I started to import the freeRTOS with the MegaBlink sample. After compile, I have one error that I couldn't fix, which is undefined reference to 'systemtick'. I have the time.h in my project, but I still have the error. In addition, I found a file called systemtick.S, is this the function? how could i link this to my project. please advice detail. thank you.

I'm afraid I don't know what the MegaBlink example is and the functions and files you refer to are not part of the FreeRTOS distribution so we can't really provide direct support. If you can tell us where the files are from and which chip and compiler you are using we may be able to provide some generic help. Alternatively you could ask whoever supplied the files for support.

Regards.

Hi, thanks for the quick response. I've got that example project from this other post in the website. Please forget about it. In fact, I would like to port the freeRTOS in my arduino ATmega2560 on Atmel Studio, so I look into the GCC folder and couldn't find the right processor folder. Can you tell me more detail about how to set it up? what other thing I need to do in order to get the RTOS running on my arduino ATmega2560? Thanks a lot! Great appreciate your help! Regards, GBL

The first thing to note is that the official FreeRTOS download contains a GCC port for the ATMega, but not the XMega - which I think that part is. That said there are plenty of people using FreeRTOS on XMega parts and you will find ports in the Atmel section of the FreeRTOS Interactive site.

The first thing to do would be to get a program that does not use FreeRTOS running on your hardware with Atmel Studio - then once you are sure your environment is working as expected - add in the FreeRTOS source files. In your case the port layer files you require are in the FreeRTOS/Source/portable/GCC/[whatever] directory - where [whatever] is whatever the directory is called in the contributed XMega port.

Regards.