Hi
I use a crystal in my project , how should I set the pins , as outputs or inputs ?

thank you .

 

hi Gag,
We need more details of the circuit to which the xtal is connected.
E

 

thank you

it is 16f628 and 16f877 ,
RA7, RA6 and C1,C2

 

In the configuration settings you select the oscillator type depending on the crystal frequency. That takes over those two pins and you don't need to do anything else.

 

hi,
All you have to do is to connect the xtal across the 16F877 pins 13 and 14. [40 pin DIP]

E

 

In the configuration settings you select the oscillator type depending on the crystal frequency. That takes over those two pins and you don't need to do anything else.

thank you

 

so when I set the ports
I just put this line ?
movlw b'10000000' ;set Portc
movwf TRISC

I need one input and other as outputs .
and the configuration setting for crystal.
is it correct ?

for 16f877a

 

That will make RC7 an input and RC6:RC0 as outputs.

 

But the crystal pins can not be used , correct ? as outputs or inputs

 

hi,
The 628 and 877 do not have a main internal oscillator block, so when a xtal is used, those pins are committed to the osc function.
E

 

hi,
The 628 and 877 do not have a main internal oscillator block, so when a xtal is used, those pins are committed to the osc function.
E

628 does have an internal oscillator.
thank you

 

You set the configure on the 16f628

 

628 does have an internal oscillator.

Hi Gag,
You are correct.
When I make a mistake, I back track to find out why.
I called up my 16F628 d/s and looked at the 'Special Features'.
On the PDF, it did not actually say 'Internal Oscillator'.
Re-checked on a 16F628A d/s and it says 'Internal Osc' for 16F628.
My error., should have taken more time looking.!

E

 

On the PDF, it did not actually say 'Internal Oscillator'.

It did say it, just not so prominently.

 

hi Albert,
I believe that is what I said, in my corrective post.
'On the PDF, it did not actually say 'Internal Oscillator'.

Don't misunderstand me, I appreciate your feedback.

E

 

hi
thank you all for help

it has dual speed,
How to set it to 4 Mghz ? I know other speed is 48 khz

 

Like this you set the pcon register

 

Like this you set the pcon register
View attachment 146028

thanks, that helps