Steve Addison writes:
>I am trying to generate a 77Khz signal from a surface mount pic in 10ms bursts.
>The way I have attempted to do it at the moment I require the program
>counter to increment every 0.5uS which means I need a resonator speed of
>8MHz - as the PC is incremented at a quarter of the pic clock speed.
>
>All the SMD pics in the (Farnell) catalog are 4MHz devices - and here's the
>stupid question - will I be able to use an 8MHz resonator?

I know it takes another part but you might consider using a 555 timer tuned
to 77KHz.  You could then gate the signal with a nand gate or something.  You
MAY be able to power the 555 from your I/O pin so that you turn the 555 on/off
to make your bursts.  I personally would let the PIC do it like you're wanting
to do but I wanted to suggest this.

--

            -- Paul Greenwood --  (pablo@austin.ibm.com)

Succumb to natural tendencies.  Be hateful and boring.