Introduction to Multi-Tasking In Interactive C

In interactive C, it is quite simple to run talks simultaneously.

In fact, the processor is doing something called time splicing where it allocates a splice of time to one process and then another. This makes it seem like the processes are running simultaneously. In other words, the microprocessor may be working on process #1 for 5 milliseconds and then process #2 for 5 milliseconds, then back to process #1 again.

Commands to know for multi-tasking in IC:

int start_process(function());

Returns an integer. This integer is the process’ PID. Since multiple processes will be running, each process must be associated to a PID in order to distinguish them.

void kill_process(int pib);

Kills the process associated to the PID in the function call.

Short example from http://www.vorlesungen.uni-osnabrueck.de/informatik/robot00/doc/books/martin.pdf :

This short example starts a process to check a sensor, sleeps for 1 second (while still checking the sensor) then kills the process using the PID obtained.

void check_sensor(int n){

while (1){

printf("Sensor %d is %d\n", n, digital(n));

}

void main(){

int pid;

pid= start_process(check_sensor(2));

sleep(1.0);

kill_process(pid);

}

To see a longer example of multi-tasking in Interactive C, see Sample Programs.

Last Updated July 13^th, 2006

By Eric Savoie