Problems with getting a crystal frequency of 20Mhz

[scdoro]

Crystal Frequency

Hi, I am having problems in getting a crystal frequency of 20Mhz when a 20Mhz crystal is used when connect to my PIC16F872. I only can get a freq of 800hz at the start when power up not even to the extend of downloading my program yet. Did anyone know why ? thanks

 

[IanP]

Re: Crystal Frequency

What capacitors do you have connected to OSC1 and OSC2?
For 20 MHz they should be 15-33 pF.

Other posibility is wrong crystal.
Microchip recommends: 20 MHz EPSON CA-301 20.000M-C ± 30 PPM..

 

[KrunCH]

Re: Crystal Frequency

Maybe the configuration bits are not set accordingly. They should be set to HS_OSC for high speed crystal operation.

 

[Ghosh Debalina]

I have same problem with 20 Mhz oscilltor. Mine is 4 pin oscillator. 1> n.c ,2> gnd ,3>output,4> vss. I am giving the output of oscillator to the osc1 of pic microcontroller 16f874a. but oscillator is working on few pf khz not on 20 Mhz .
can anybody help me in this case.