--- Andre Abelian <aabelian@mason-electric.com> wrote:

> Web,
> 
> Sorry for confusing question. My question is in
> general: on pic project pic18f4550
> I am using external oscillator and configuration
> setting is EC and I did a
> test to change it to HS then it worked and I forgot
> to change it back to EC
> but the project is working and I am worried about it
> to understand the difference
> between the EC and HS. 
> 
> Now let me answer to my own question:
> The only different between EC and HS is if osc out
> pin is used as I/O  
> EC must be set then internally OSC out pin will be
> disconnected and be ready to use as I/O but when
> HS is used OSC in and out pins are used OSC out pin
> as I/O can't be used and 
> it will simply oscillate. In my case I do not use
> OSC out pin as I/O so 
> I do not need to worry about it.
> 
> thank you
> 
> Andre
>  
> 
> 
  EC is "External Clock with FOSC/4 output(on OSC2)"
  while ECPLL is "External Clock with PLL enabled
and FOSC/4 output on RA6(on OSC2)"

  I suggest strongly you choose and fix the OSC type.
I do not have a clear understanding with the ext OSC
you are using so just match to the appropriate source
and OSC type you are using. If you read the section on
HS osc you will notice the capacitor that can be used
with parallel crystal. It states that diff caps alters
the startup time......... So unless you have some
strict requirement you need to take this into account.


John


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