Avark Files

AVARK is a round robin kernel curently for the AVR platform.

The kernel consists of four header files.
1 avark.h
2 semaphore.h
3 terminal.h
4 time.h

avark.h has the main kernel. (the context switcher and scheduler and other important variable declarations)
semaphore.h has code to implement semaphores
terminal.h has code to implement command line interface; commands being passed down the USART.
time.h has code to keep track of time (system clock); also needed for delays.


AVARK is being developed on the ATmega640 right now. It is using the TIMER2 of ATmega640 to schedule the processs. It can schedule upto 8 processes.

To use AVARK (minimalistic), follow the instructions:

1. Include avark.h

2. Define the macro MAX_PROCESSES to the number of processes between which you want to do multitasking.
eg: #define MAX_PROCESSES 2

3. Declare the stack for each processes. Stack will be array of type K_STACK. Its length will be your desired stack memory.
eg: K_STACK task1_stack[64];
    K_STACK task2_stack[80];

4. Define all the processes you want to execute simultaneously as normal functions. It is important that the functions neither return nor accept any arguments.

eg: void task1()
    {
          ....
          ....
          ....
    }

    void task2()
    {
          ....
          ....
          ....
    }



3. Do everything else that you need to do that is declare other variables, initialise peripherals etc....

4. Initialise the kernel using the K_init() function. K_init takes arguments in the following pattern
    K_init(name of first process, address of last element of first process stack, ....same for otherprocesses);

eg: K_init(task1, &task1_stack[63], task2, task2_stack[79]);

5. call K_start() function.


The kernel will now multitask between the two processes.

Compile the main c file (from which you include avark.h) using avr-gcc compiler in the usual way.