16F877 test Board Problem

[janosandi]

hello Guys
i had some problems with trying Pic 16f877 for first time but now its ok with help of you
i've built a new board to test my project but now it works good only when i touch the negative line by hand.
do i have to connect the unused pins to GND or Else ?
any idea guys

thx for ur help

 

[DNA Robotics]

If MCLR is used for programming, you may need a 10K ohm pullup resistor on it.

 

[janosandi]

100n Cap & tought its ok but not still need touch to work
& i've connected the rest of port C pins to GND but the same


& when i connect 10k pullup resistor to MCLR its not working

 

[PA3040]

Hoped this will help



How about your power supply . does it have smooth capacitor

 

[janosandi]

Ya Right its ok But why i didnt Face this problem with other pics ?

 

[PA3040]

Other PIC mean with same hardware ?

 

[Ranbeer Singh]

What type of frequency ( internal or external) you are using to driving your controller? If it's from external crystal..check suitable capacitor and check crystal output. And yes MCLR pin should be pull-up with a described #2 post resistance value or other.

 

[janosandi]

My Board is working now
i had some projects on 12Fxxx& 16Fxxx & id didnt connect anything to MCLR
but im thinking now maybe i've used MCLR pin for input or output

i'll check it this evening
thx Guys

 

[Ranbeer Singh]

Too right! you can use MCLR as a I/O pin but it will be define in codes or by selecting configuration bits setting in IDE.