multi-tasking

[peu]

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]

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]

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.

[rmteo]

Driving fuel injectors?

More likely simultaneous output of 4 R/C PWM pulses - 1-2mS width, 50Hz frequency.

[malc-c]

More likely simultaneous output of 4 R/C PWM pulses - 1-2mS width, 50Hz frequency.

LOL - on this occasion you're not even warm.....

[tiger_bel]

multi tasking ??? one processor does always one thing.....

quite easy problem:
all depends on your timing - use high speed oscillator (20Mhz)
create a timer under interupt ( interupt 1ms) relaod timer
create counters as much as you need.
increment the counters on interupt and compare with value
if match - relaod counters with new value ...
beware that interupttime is smaller than 1ms !

all other calculations can be done out of interupt.

rgds
tb

[mackrackit]

The only way you can have a PIC do more than one thing at a time is to have part of it done with hardware and the other in code. Sounds like you are going to need to use a timer so it might be doable.

Look at interrupts in general and DT's instant to be specific for ideas.

But do not be embarrassed to tell us about your project, unless...