Before I hang my hat on an RTOS for my Atmega projects I wanted to know what was out there and how popular the various rtos platforms were. Here is a summary (original list from here). As of this writing, FreeRTOS for DuinOS is a hands down winner.
Update: 20100112: DuinOS : DuinOS is a port of freeRTOS on Arduino that tries to preserve the development environment by hiding much of the freeRTOS fundamentals as possible. I have mixed feelings on this and have been reverse engineering my sketches to expose as much of freeRTOS as possible.
Update 2010112: AVRx: Although not actively expanding, there seems to be a yahoogroup, avrx, that is active. This is worth a second look at.
Update 2010112: TinyOS: This is an OS for a sensor networks. There is mixed information on how actively supported and used this OS is. Still researching.
FreeRTOS: A Free RTOS for microcontrollers Currently very active. There is an interesting fork called DuinOS for use with the Arduino IDE that works very nicely. Can be found here and a discussion can be found here. I’ve done this fork on the Arduino Duiemonolove and peeled back the covers. TBD in another section of this blog with performance metrics.
AvrX: Real-Time Kernel for AVR processors Not very active. the 2.6 version compiled from C looks interesting. The yahoogroup for discussing AvrX is moderately active
YAVRTOS: Yet Another Atmel AVR Real-Time Operating System Just what it sez, yet another RTOS. Self described as a project and not a product. Not regourisly tested.
AVRAsmOS: A tiny OS for small AVRs V1.0 active November 9,2009. No web page or documenation.
pc/OS RTOS Kernel (for larger AVR processors >= mega128) There is some activity. Documentation is sparse. No porting or installation guidance. Based on a 1992 rtos
COMATOS Not active.
Task dispatcher Is what it is, a dispather. Not an RTOS
Opex A simple scheduler, not an RTOS
mthreads Another thread only library, not really an rtos
RTK low activity. Nice starting point for someone interested in creating their own RTOS.
csRTOS not active
Adam Dunkel’s Protothreads Fairly old simple threading code. Not really an RTOS. Last updated in 2005.
Femto OS Active, looks interesting but the license is restrictive and requires all of your application IP to be freely distributed. Lays claim to your IP (intellectual property) because your code gets embedded with femto OS. If you think what you are creating is every commercially viable you probably do not want to use this.
TinyOS Spotty activity, supposedly for sensor networks, site links are old or not active, forum and wiki seems to have been compromised with spam, look at them on your own risk. Best link I have found is here
Contiki Heavy on the TCP/IP requires 2k ram 40k rom
pico OS not active
scmRTOS: a C++ cooperative OS with Mit license Last updated by author 2006