multi-tasking

malc-c · - 26th December 2009, 19:49

Guy's, just need some general pointers on how to move something forward. I don't want to go into actual code at this time for personal reasons, more simply for guidance as to what to use

Lets say I had a routine that calculated a value and then I used that value in a pause statement to control how long a pin remains high. This works fine for one output and is achieving the desired result in my tests. However I now want to replicate this 4 times, which causes me a slight problem.

If I had something like:

Calculate value 1
Calculate value 2
Calculate value 3
Calculate value 4

high pin 1
pause value 1
low pin 1

high pin 2
pause value 2
low pin 2

etc etc

The problem is that the total time all pins are off is the sum of all the other pause values. ie pin one is low for pause value 2 + value 3 + value 4. This is not what I want. I want to have pin 1 pulse at the rate set by value 1 and pin 2 at the rate set by value 2 etc etc..

What would be the the best way forward.

**peu** · - 26th December 2009, 21:08

lets say you need to pause these pins starting from the same initial port status and time:

porta.1 15 secs
porta.2 10 secs
porta.3 5 secs

you can do this:

porta=%00000111
pause 5
porta=%00000011
pause 5
porta=%00000001

is this what you are looking for?

malc-c · - 26th December 2009, 22:12

Thanks for the input, but not quite as the pause period is not static.

Each pause will be variable each time the loop runs round, and needs to be totally independent. In effect I need to run 4 loops simultaneously so that the pause delay in each has no affect on the others.

**spcw1234** · - 26th December 2009, 22:25

Driving fuel injectors?

Depending on what kind of time frame you are talking it could be done by running a timer.

#1 on at x time
#1 off at x time
#2 on at x time
#3 off at x time
#4 on at x time
#4 off at x time

Each loop can adjust the values that the timer falls on for the on and off times to adjust your output periods. Interupts could be used depending on how time sensitive you need it.