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monica
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| really strange thing in pic16f88 |
 Posted: Wed Oct 15, 2008 3:49 am |
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Hi
i have a strange thing.
i programed the chip to blink a led and it works-BUT only if i touch the pins with my finger...or with anything metal...
i tryied in a few circuits- and it blinks only if i touch the PINS.
WHAT IS THAT ?
thanx. |
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Rohit de Sa
Joined: 09 Nov 2007
Posts: 282
Location: India
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| Posted: Wed Oct 15, 2008 5:01 am |
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Monica,
Whenever you post a problem please include a concise, but adequate and relevant description of the hardware and code you are using. It sometimes also helps if you mention the version of the compiler and other software tools you are utilizing.
| Quote: | | it works-BUT only if i touch the pins with my finger...or with anything metal... |
There could be several reasons why this is happening. I remember I used to frequently forget to connect the PIC ground pin to circuit ground. Touching the PIC pins (thereby providing some sort of grounding path) used to cause operation, which was, naturally, highly erratic, to say the least!
If you have specified in code that you are using an external crystal, and have not added the crystal to the circuit, touching the OSCx pins on the PIC may cause it to work, again, very erratically. Even if you have used an external crystal, it is possible that you are not using the proper crystal stabilizing capacitors. Refer to the device datasheet for guidelines (Section 4).
Sometimes, if input pins are allowed to float, the device may lock up due to high frequency switching of inputs. Touching the pins 'loads' them, and allows your device to work.
It can also be a case of you getting a piece of not-so-good silicon (though this is highly unlikely).
Rohit |
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monica
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| Posted: Wed Oct 15, 2008 9:44 am |
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thanx
i used internal osc , and there is no special hardware-only a led goes from pin b0\b1\b2. gnd is connected. |
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Ttelmah
Guest
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| Posted: Wed Oct 15, 2008 10:25 am |
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Have you got the fuse 'NOLVP' set?. Have you got the fuse 'NOMCLR' set?.
If not, signals on B6, B7, or RA5, could stop the chip running.
Best Wishes |
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MONICA
Guest
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| Posted: Wed Oct 15, 2008 11:28 am |
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| THANX WORKS ! |
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