Hi,
I've been using high voltage programming since I started using PIC. I just want to know what's the difference between these three.
1. The configuration setting.
2. One IO pin cannot be used.
3. The supply voltage of the programmer.


Is there any other difference beside what I have mentioned above?

Thanks

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As a safety feature, you cannot turn off LVP via LVP.
Also with LVP enabled, it is very easy for the PIC to get stuck in programming mode if you connect the LVP pin incorrectly in a project.

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I’m programming my PICS through serial port. I’m not giving any supply voltage from outside.

Also I never enable LVP fuse but its programming nicely.

Is it my circuit is a low voltage programmer or high voltage programmer?

Thanks.

Attached Images

87X Programmer.JPG (15.2 KB, 22 views)

 

Serial port can supply 13 V for high voltage programming. I use parallel port programmer.
Not sure about yours, I wonder why the GND is connected to Vdd pin?

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Maybe it uses a positive ground?
It looks like it is neither because Vss of the PIC is not connected to anything except the zener. Unless they are using the PICs internal diodes to feed the (-) from the signal leads. Definitely something I wouldn't rely on. Does it actually work as wired?

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