still don't have solution!!!

[Macgman2000]

Why not just use an LM324 quad opamp. Set up a couple in a feedback oscillator at the frequency of your choice. Run the output of the oscillator (triangle wave) into a third gate as a comparator. From the pic all you need is a couple of resistors to set your DC level at the right place to slice a 50% duty cycle. Easy....you can turn it on and off when ever you want.

Nick

[rmteo]

You will not get 120KHz - the closest is 125KHz. Assuming a clock of 8MHz, this will give you 125KHz on CCP1 (RC2) with a PIC1F877A.

TRISC = 0  'PORTC all outputs
PR2 = 15  'Load Period Register
CCPR1L = 8  'Set 50% duty cycle
CCP1CON = %1100  'PWM mode
T2CON.2 = 1  'Start TIMER2