ChibiOS is a portable,open source RTOS…ChibiOS can be downloaded from source forge
http://sourceforge.net/projects/chibios/
Extract the downloaded file..Inside the folder you can see a folder named Demos inside that our board will be listed ARMCM4-STM32F407-DISCOVERY inside that folder there will be a main.c….Edit that main.c file
#include "ch.h"
#include "hal.h"
int main(void) {
halInit();
chSysInit();
palSetPadMode(GPIOD, GPIOD_LED4, PAL_MODE_OUTPUT_PUSHPULL); /* Green. */
while (TRUE) {
palSetPad(GPIOD, GPIOD_LED4);
chThdSleepMilliseconds(500);
palClearPad(GPIOD, GPIOD_LED4);
chThdSleepMilliseconds(500);
}
}
palSetPadMode configure the I/O as input or output….palSetPad and palClearPad is similar to High and Low…halinit is the intialization of hardware abstraction layer and chsysinit is the intialization of kernel…
Open a terminal and change directory to that folder
cd ChibiOS_2.4.1/demos/ARMCM4-STM32F407-DISCOVERY/ make st-flash write build/ch.bin 0x08000000
Happy Hacking 🙂
HalfaGeek 
amazing. the first time for me something like this just worked out of the box.
I had a hard time with freeRTOS just to realize that there’s no HAL so I want to try ChibiOS
🙂