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Reading an analog voltage with a digital input

 
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arunb



Joined: 08 Sep 2003
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Reading an analog voltage with a digital input
PostPosted: Thu Mar 22, 2007 9:25 am     Reply with quote
Hi,

How can I use a 16F648A mcu to read an analog voltage (0 to 5 V range) ?

The 16F648A does not have a ADC, but it has a comparator. Also mention what the accuracy of the result would be ???

thanks
arunb
libor



Joined: 14 Dec 2004
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PostPosted: Thu Mar 22, 2007 11:02 am     Reply with quote
Using another port of the PIC as an output you can charge/discharge an RC element that is connected to the comparator's first input. The timepoint, the comparators triggers corresponds to the analog voltage on the second input of the comparator.
Accuracy: depends on how slow is your RC element, this also affects the 'sampling frequency'.
PCM programmer



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PostPosted: Fri Mar 23, 2007 12:26 pm     Reply with quote
Quote:

How can I use a 16F648A mcu to read an analog voltage (0 to 5 V range) ?
The 16F648A does not have a ADC , but it has a comparator.

This project may help:
http://web.archive.org/web/20060427170840/http://www.cappels.org/dproj/wfc/wfc.html
Mark



Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA

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PostPosted: Sun Mar 25, 2007 8:57 am     Reply with quote
For slope
ww1.microchip.com/downloads/en/AppNotes/00863a.pdf

For delta
ww1.microchip.com/downloads/en/AppNotes/00700a.pdf
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