As the title say, How to program the m4 without the arduino abstraction? In other word, I don't want to program it using arduino IDE/library. I want to know, how to setup compiler, upload to the main mcu, and if its possible, even use the freescale RTOS mqx/FreeRTOS. What is the .fw format? How to generate the .fw format from gcc or common IDE like keil, IAR, crossworks or Kinetis studio? Any linker script required? Any already writted linker script available? Why? Because i like going low level, real time is more easy with interrupt capability/threading (RTOS). Doing simple thing in arduino is simple, but as the complexity increase, it become harder on arduino than bare metal because programming with lot of delay in a single thread as its limit. I checked the documentation, and i didn't find any information on that. During the campaign on kickstarter, i asked if it would be possible to program it without arduino ide, and they said yes.