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Author Topic: HELP! cannot turn on PIC16F877A  (Read 1121 times)

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Offline SzeHanTopic starter

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HELP! cannot turn on PIC16F877A
« on: January 03, 2012, 03:38:40 AM »
Hi,

I'm using PIC16F877A to control a 12v DC motor and a 24v stepper motor. I have two voltage regulator LM7812 and LM7805 in my circuit. I used 24V 800mA AC-to-DC adapter to supply my circuit. My circuit goes well in breadboard so i solder it into stripboard.

After i solder it into stripboard i found out that my microcontroller become very unstable. Some times my circuit works but sometimes my PIC16F877A does not give any output. The "high" output was around 3v (it suppose to be 5v) or maybe lower (0.5v for "high" output pin). Some times i need to wait the PIC16F877A for around 10mins to get a 5v output where the output voltage will increase slowly until it reach 5v but not all the time it will increase!

Is it because of lack of current to support the whole circuit? If it is because lack of current then what should i do? I attached my full schematic at here.
Thank you.


Regards,
SzeHan



Offline Soeren

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Re: HELP! cannot turn on PIC16F877A
« Reply #1 on: January 03, 2012, 08:27:34 AM »
Hi,

[...] My circuit goes well in breadboard so i solder it into stripboard.

After i solder it into stripboard i found out that my microcontroller become very unstable.
[...]
Is it because of lack of current to support the whole circuit? If it is because lack of current then what should i do?
Since it worked in the breadboard, there's not that many things to check, assuming you used the same supply for the breadboard.

Either you (ESD) damaged the controller between taking it out of the breadboard and testing the stripboard build, or you didn't connect it up as in the breadboard.

Examine your connections very thoroughly and use an Ohm-meter or continuity tester to check connections - I'd guess that there's around 95% chance that something went wrong there.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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