PIC won't work with capacitors

nuttaphong191

Mar 31, 2007
33
Joined
Mar 31, 2007
Messages
33
I have a very simple circuit that oscillates an LED with a program on the 16F628.
I am using a 4Mhz crystal and I find that the program will not run at all when the capacitors connecting each pin of the oscillator to ground are connected, but runs when they are connected.I am using 22pf capacitors, I have tried 10pf and 45pf. The oscillator is a crystal oscillator and it recommends 18-35pf in the datasheet. Any ideas?
I need to stabilise the oscillator as it will be used for data output. It's a PIC16f628
::)

 

AN920

May 15, 2005
359
Joined
May 15, 2005
Messages
359
nuttaphong191 said:
I have a very simple circuit that oscillates an LED with a program on the 16F628.
I am using a 4Mhz crystal and I find that the program will not run at all when the capacitors connecting each pin of the oscillator to ground are connected, but runs when they are connected.I am using 22pf capacitors, I have tried 10pf and 45pf. The oscillator is a crystal oscillator and it recommends 18-35pf in the datasheet. Any ideas?
I need to stabilise the oscillator as it will be used for data output. It's a PIC16f628
::)
What you are saying does not make any sense.
 

esp1

Apr 15, 2007
42
Joined
Apr 15, 2007
Messages
42
hi,
Look at  page 93 of the 16F62X datasheet.

Are you using a series or parallel cut crystal?  also note the possible requirement for a series resistor in one leg of the crystal.

Have you correctly configured the PIC using the _CONFIG, to suit your crystal?

 
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