Delay_ms calculation

[aschenk]

I am trying to create a variable clock pulse out of an IO on a port for an L297 stepper driver. I use an ADC to measure the input voltage between 1 and 5 VDC. That value is converted to a time value between 1 and 100 ms which is placed in the delay_ms() function. I noticed howver that the actual delay is much longer than it should be . Does the delay_ms function have anything to do with the oscillator frequency?

I am using a PIC 16F877A with a 4 MHz crystal. I'm simulating all of this using Proteus to do some initial development.

[Ttelmah]

Of course it is dependant on clock frequency. The 'clock', is the only time 'source' in the chip...

To get 'correct' delays, two things have to apply:

1) The timing set in the 'clock' statement, must match the actual oscillator you are using.
2) If using a simulator, the timings set in this, must also match the oscillator.

Best Wishes