Pulsein problem

[Sym-1]

Using an 08M, I'm trying to count pulses on two inputs, and stop a pwmout if either goes out of a range.

To achive the required pwmout frequency, I have dropped the clock speed to 1Mhz, using poke $8f, %01000000.

The problem is, at 1Mhz, if a pulsein times out, the program seems to crash.

At normal 4Mhz speed, it runs ok.

 

[eclectic]

Sym.

Post your program and the circuit please.

 

[Technical]

The PIC has an internal watchdog which resets the chip after 2.3 seconds of inactivity.

This does not occur with a pulsin timeout at the correct 4MHz, as that is 0.65 second maximum. However at a 'hacked' speed of 1MHz your maximum pulsin is 2.6 seconds, hence the reason the chip is resetting.

So you can't use pulsin like this at 1MHz.

 

[Sym-1]

Thanks.
Looks like I need a new design.

 

[hippy]

Do a Forum search as there is another way to reduce the PWM frequency and stay operating at 4MHz or 8MHz. It involves poking the PWM pre-scaler but I cannot recall the details.