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Message |
evaradharaj
Joined: 15 Jan 2009
Posts: 60
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| PIC reset |
 Posted: Mon Mar 08, 2010 12:50 am |
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Hai,
I am using PIC16f877a. It is often resetting. I am not using WDT. I checked that, it is not enabled. But the problem continues....
I am using ADC using LM324 IC.
My code is like this,
| Code: |
void main()
{
printf("welcome");
while(1)
{
printf(adc Value);
}
} |
output:
wel wel wel.... if I press the IC then, the output is welcome welcome....sometimes the adc value.....
What is the problem sir?
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embedding innovation in engineers |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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John P
Joined: 17 Sep 2003
Posts: 331
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| Posted: Mon Mar 08, 2010 10:54 am |
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| Is your chip in low-voltage programming mode, and what have you done with PortB.3? I'd pull the reset high with a resistor too, just to be on the safe side. |
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evaradharaj
Joined: 15 Jan 2009
Posts: 60
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| reset |
| Posted: Mon Mar 08, 2010 11:19 pm |
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Thanks for your replies......
Yes, I am using Low voltage programming mode. That pin is left free.
I am having +5 v supply which is having 7805 and 1000uf from input and 22uf in the output sides.
Is that any problem....
The pullup resistor is connected to the MCLR pin.
I am using max232 board also.
What is the best way to save my pic?
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Wayne_
Joined: 10 Oct 2007
Posts: 681
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| Posted: Tue Mar 09, 2010 2:59 am |
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I would go with hardware fault, dry joint, bad connection etc.
BUT what is this line suppose to be ? printf(adc Value); ?
Where is adc and Value defined and what are they set to ?
What are your fuse settings ?
Does it work if you just touch the pins of the device or do you have to put pressure on to it to push it down ?
Are you using a bread board, surface mount etc ? |
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evaradharaj
Joined: 15 Jan 2009
Posts: 60
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| soldering |
| Posted: Tue Mar 09, 2010 4:45 am |
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I am using dot board soldering.. my fuse settings are NOWDT,XT,NOPUT,NOBROWNOUT,LVP
when i press on the pic microcontroller near top and bottom (at a time ) it is working(the printf statement on the terminal is coming).. other times its not working... many times its coming as "welcome" only
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embedding innovation in engineers |
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John P
Joined: 17 Sep 2003
Posts: 331
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| Posted: Tue Mar 09, 2010 7:29 am |
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"Yes, I am using Low voltage programming mode. That pin [RB3] is left free."
Sigh.
: RB3 should not be allowed to float if LVP
is enabled. An external pull-down device
should be used to default the device to
normal operating mode. If RB3 floats
high, the PIC16F87XA device will enter
Programming mode.
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evaradharaj
Joined: 15 Jan 2009
Posts: 60
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| RB3 |
| Posted: Tue Mar 09, 2010 10:11 pm |
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I have used more than 100 boards with RB3 left free...
But they have worked perfectly for some days...
After that they will not work.....
Is RB3 free the problem?
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embedding innovation in engineers |
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John P
Joined: 17 Sep 2003
Posts: 331
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| Posted: Wed Mar 10, 2010 3:13 pm |
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| So, you tried tying pin RB.3 low, and what happened? |
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