From http://www.udoo.org/forum/threads/how-to-program-the-m4-without-the-arduino-abstraction.4210
As the title say, How to program the m4 without the arduino abstraction?
One way is to use FreeRTOS; Download the zip and look for the documentation.
What is the .fw format?
Binary currently is the current method; need to use udooneo-m4uploader copy binary into memory and start the M4. http://www.udoo.org/forum/threads/how-to-use-m4-processor.3353/#post-16364
I know .fw is some sort of binary and i can use udooneo-m4uploader to upload it, but how to generate it? Is .fw a renamed .bin? a renamed .elf? Absolutely no documentation at all on the m4 coprocessor for udoo.
It is binary, just rename.