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PIC WPU and Comparator module

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navarretemarce

New Member
Anybody knows if the internal weak pull-ups can be enabled and work if the pins are asignated to the VIN of the embebed comparator module?
(I am using the PIC 12F629)
I know it is analogic imput, but anyway if they could be used I could spare external components.

Thanks a lot.
 

Sceadwian

Banned
I'm not knowledgeable about the inner workings of PIC's but even if you can't use that pin's pullup you could use the pullup from a neighboring pin instead, but all this is going to do is save you one resistor from the voltage divider network. Is it really worth it?
 

navarretemarce

New Member
Thanks, for your answer. Unofrtunatly I dont have a PIC to test it my self. And the information provided about the comparators in the datasheet is really poor.
One resistor is one resistor :D
 

Sceadwian

Banned
You can't universally charactorize the pullups of a PIC though, look at the data sheets, there's a wide range. So you'd need to take that into acount.
 

navarretemarce

New Member
Thanks for the answers.
In the case of the PICs I am working with: 12F629, 16F628, the internal weak pull-ups are 4K7.
Unfortunatly this p-ups are only asignables to Digital ports and not to the analog comparators.
 

Sceadwian

Banned
nava, you can set an unused I/O line to be a pullup and externally wire it to your analog comparator.
 
Is there a need to use the internal pullup at all?, as the comparator has the internal Vref that can be set by software. Check the data sheet for any of the eight different comparator modes that can used. Enable and set the VRCON register to Vdd, if that's what you want, and you should be good.
 
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