Editing Freertos posix Development

This wiki describes the development of freertos_posix - a POSIX wrapper for [http://www.freertos.org/ FreeRTOS]. The wrapper has been used for deploying the [[DsPIC30F 5011 Development Board | dsPic33 development board]].

==Introduction==
*freertos_posix is a POSIX wrapper for FreeRTOS. 
*The platform independent files (apart from those those under '''/posix/asm-dsPic''') are saved under '''/posix'''. 
*Platform dependent files (such as drivers) are stored under '''demo_posix/xxx''', where '''xxx''' is the name of your target platform.


===Source Code Repository===
*The most up-to-date development can be found at repository [http://chungyan5.no-ip.org/vc/?root=freertos_posix freertos_posix]


===Features===
*Not all POSIX functions are implemented, the followings are the major functions developed. You are invited to contribute new functions and improve the existing ones.
#POSIX Thread: mapped to FreeRTOS task (pthread.h, and unistd.h)
#Mutex functions: mapped to FreeRTOS semaphore
#Filestream operations (e.g. open, read, write, lseek, etc): not associated with any FreeRTOS functions (unistd.h)
#Time and clock functions (e.g. time and clock): using the context switch timer required in FreeRTOS (time.h)
#Socket API: mapped to uip: Please note that the socket API is only posix-like and it is NOT compatible with standard POSIX operation.
*Extra functions include:
#a coroutine task scheduler, in order to run multiple POSIX threads in a single FreeRTOS Task (see pthread.c and system.c)
#dsp library API


===Documentations===
*You can also generate HTML documentations in the source code using [http://www.stack.nl/~dimitri/doxygen/ doxygen] 
**Goto '''/posix''' and use the Doxyfile to generate documentation under '''/posix/doc'''


==Architecture==
*Refer to software architecture from [[Multi-purpose_Embedded_System#RTOS | here]]


==POSIX Threads Scheduler==
*The task scheduler is based on [http://www.freertos.org/ FreeRTOS] incorporating coroutine developed by [http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html Simon Tatham]. The scheduler API is wrapped by the [http://www.die.net/doc/linux/man/man2/ POSIX] Thread API.
**e.g. pthread_create(), usleep(), etc.


==POSIX Driver Development==
*Software drivers are developed to allow users at Application Level to use the hardware (e.g. ADC, DAC, UART, NVM etc) through the [http://www.die.net/doc/linux/man/man2/ POSIX] System call API.
**e.g. open(), write(), read(), ioctl(), lseek(), etc.
*An example of how to develop drivers for Microchip dsPic33 devices can be found [[Programming Tips | here]]


==Power Management==
*to be added