Well, for starters.... What model of PIC chip are you using? and what is
the rated speed? Lastly, what kind of Xtal was this, and are you sure the
15pF caps are the right value? I know they are for a 4Mhz oscilator,
because I've hooked up my 16c84's with this configuation many times before.
There are tables and equations given in the data sheets to help you
calculate the proper caps for that frequency of oscilation. Also, if you
are trying to drive a 16c84 at this frequency, you can forget it bacause
this component is rated at 4Mhz and 10Mhz. Some may be able to be over
clocked a little, but I would think that 50% would be a little bit more
that they could handle.



At 09:20 AM 10/27/97 -0600, you wrote:
>Hi, I'm relatively new to the PIC and I was hooking up a little test
>circuit to simply turn on an LED.  I was using a 16Mhz crystal as a clock
>in the following configuration:
>
>        CLKIN   -----------
>                     |    = 15pF
>                    XTAL  +----GND
>                     |    = 15pF
>        CLKOUT  -----------
>
>I programmed the chip using MPLAB and set the clock config bit to HS.  This
>didn't work.
>
>After trying a few other things with no results, I replaced the clock with
>a 4MHz version and used the XT option when programming.  This circuit
>worked perfectly.  Unfortunately the design I eventually would like to
>build would work best with a 16MHz clock.  Can someone give me some
>pointers at to what could be wrong? Unfortunately I don't have a scope to
>be able to watch the clock.
>
>
>Other relevant info:
>PIC 16C63
>PICSTART PLUS programmer
>Hooked MCLR high through pull-up resistor
>
>
>                                                        Thanks,
>                                                        Dennis
>
>
Hope this helps

Shannon Spurling
MOREnet
Network Operations
shannon@more.net
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Columbia, MO 65201
(573) 882-4548

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