How to set timer up for simultaneous 4ch PWM, RS232, I2C?

[Neil_J]

I am developing a project that has a few different signals that all need to run simultaneously. I've done a few projects that only done one or two things but this one seems a little harder to me... My signals are:

- 4-channel PWM (red, green, blue LED's and 1x DC speed control) at about 4.4 mS
- RS232 8,n,1 @ 2400bps (rx + tx)
- I2C EEPROM (24AA08)
- Infrared remote using Philips RC-5 protocol
- Also some other signals that doesn't relate to the question..

I am hoping to do all this on a PIC16F684 @ 8 MHz.

The only way I can think to do it is to use a 8uS timer and four variables (1 for each signal type) to offset the timer. I don't see how I could generate an interrupt for each, and if I did an interrupt every 8uS I couldn't get that much done between them.

Does anyone have any suggestions, or possibly some example code?

Thanks,

Neil

[PCM programmer]

I would use the multi-tasking approach, as described in this thread:
http://www.ccsinfo.com/forum/viewtopic.php?t=17189

Low speed processes are checked or updated at the tick rate (10 ms).
These would be keypad, checking RS-232 receive buffer, etc.
(This assumes an interrupt-driven RS-232 receive fifo).

High speed processes run independently at their own rate. These
could be running on a timer interrupt that runs faster than the tick rate.
(A separate hardware timer, other than the tick timer). This could
be the RC-5 receiver and the software PWM.

I'm not sure if you can do all of this in a PIC, unassisted by external
hardware. Normally, I try to use as many of the PIC's hardware
modules as possible.