Cytron Technical Forum

hello.....
I am doing a burglar alarm in which I used pic16f877a. On the process of doing this project I encountered problems regarding the crystal oscillator. Why is it that it needs to be discharge first or I need to touch it every time for the whole system to function?have you also experienced this problem? do you have any idea how to get rid of this? please we need the answers ASAP...

big nose WROTE:hello.....
I am doing a burglar alarm in which I used pic16f877a. On the process of doing this project I encountered problems regarding the crystal oscillator. Why is it that it needs to be discharge first or I need to touch it every time for the whole system to function?have you also experienced this problem? do you have any idea how to get rid of this? please we need the answers ASAP...

I never experienced. I wonder how your soldering hardware and how your crystal position. So, can you show your hardware picture?

big nose WROTE:hello.....
I am doing a burglar alarm in which I used pic16f877a. On the process of doing this project I encountered problems regarding the crystal oscillator. Why is it that it needs to be discharge first or I need to touch it every time for the whole system to function?have you also experienced this problem? do you have any idea how to get rid of this? please we need the answers ASAP...

Did you tie the MCLR pin to VDD?

no, I did not connect the MCLR to Vdd.
is it that necessary to connect it??

also to shahrul, were quiet confident on the way we soldered it. And i think there is no issue on the crystal position coz it has no polarity.....thanks for the concern anyway....

big nose WROTE:no, I did not connect the MCLR to Vdd.
is it that necessary to connect it??

also to shahrul, were quiet confident on the way we soldered it. And i think there is no issue on the crystal position coz it has no polarity.....thanks for the concern anyway....

Yes, of course you need to connect that through 10k resistor. That pin is a master clear reset pin. If it is connected to ground, then your circuit will reset. So, if you leave the pin floating, it will be any value.

ohhh...sorry,i did not notice that it is already connected.
it is attached with a 4.7k resistor with the reset button as it go through the Vdd. and the Vdd was with a capacitor as it go along to the MCLR.

Replace the Crystal. Could you post your hardware picture?

we already replaced it a couple of times but still the outcome is the same.

Please post your hardware connection. Using breadboard? Etch own PCB?... All these are important to know your circuit better. This problem usually occurs when the there's open connection somewhere.

somehow we already found a way on how to solve it.
and i guess we did the right thing because the crystal oscillator is now functioning well.
thank you guys for being such a help we really appreciate it.