Testing PIC16F877A with LED blnking program

[Anas Shafqat]

problem in led with pic16f877a

Hii,
i m working on PIC16F877A. i made a small ckt on vero board for LED blnk testing but the problem is that
"it works when i put my finger at the crystal oscillator(4MHz)".
i used CCS C Compiler as well as if tried for mikroC compiler. But problem is still the same.
i have also tried with two Caps 22pF each with the crystal.
i have also changed my Controller but still problem is there (

please can any1 help me out??

 

[tamer1221]

pic16f877a testing

buy another os

 

[nlksg]

Hii,
i m working on PIC16F877A. i made a small ckt on vero board for LED blnk testing but the problem is that
"it works when i put my finger at the crystal oscillator(4MHz)".
i used CCS C Compiler as well as if tried for mikroC compiler. But problem is still the same.
i have also tried with two Caps 22pF each with the crystal.
i have also changed my Controller but still problem is there (

please can any1 help me out??

Check whether you have the proper capacitor or not. It seems like your cap value are wrong or not properly connected.

nlksg

 

[APBeck3]

Make sure the crystal you are using is a "parallel cut crystal" - series cut won't work with that processor. Also, you may need the series resistor. The datasheet for that device does a pretty good job of spelling out the oscillator circuit requirements. Finally, verify the configuration bits are set correctly for the crystal you are using.