[SOLVED] works on bread board but not pcb

[Eng.Wad]

Hi everyone,

I designed the attached circuit for push ON/OFF led control. I did the PCB but didn't work. I tried a simple led flashing on the same pcb, but didn't work, except if it happens to ON without blinking. I did anther try using the bread board, the led will blink when I keep my finger attached to the wire going to OSC2.

I'm using PIC18F2520, I configured the bits as follows:

#pragma config OSC = HS
#pragma config PWRT = OFF
#pragma config MCLRE = ON
#pragma config PBADEN = OFF
#pragma config LVP = OFF
#pragma config WDT = OFF,DEBUG=OFF

The code is working on proteus just fine.

There might be something wrong with my configuration or cct or both :-(

Please see the attached image

 

[Eng.Wad]

I then needed to replace the OSC capacitors with smaller ones, instead of 1nF I used 15pF.

Regards

 

[alexan_e]

The proper capacitor values for the crystal oscillator are usually given in the datasheet.
Usual values are 15-22pF

See page 24 of the datasheet ww1.microchip.com/downloads/en/devicedoc/39631e.pdf

Alex