Delay question

[paul borgmeier]

Not to muddy the waters because it sounds like you have decided on another route, but for completeness ...

Start:
  PortB.1 = 1     'Set pin high        
@ NOP             'Wait....Two NOP's are neede if we want 50% dutycycle
@ NOP             'since the GOTO takes two instruction cylcles.
  PortB.1 = 0     'Set pin low
Goto Start        'Do it again. The GOTO takes the same time as two NOP's

at 4 MHz, 3 instructions on and 3 instruction off = 6 instructions per cycle, therefore f=1000000/6=166666.667 Hz (twice that noted above)

Interestingly enough the above code does 3 instructions on and 4 instructions off on 16F devices and 3 on 3 off on 18F (at least on an 18F877A and 18F452, respectively). To combat this on the 16F's, you could do something like this in ASM

ASM
here
    bsf PORTB,1
    NOP
    NOP
    bcf PORTB, 1
    goto here
ENDASM

Good Luck