gnupic: ADC using an RC circuit instead of a ADC port??
Subject:
Re: ADC using an RC circuit instead of a ADC port ??
From:
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Date:
1 Sep 2002 06:52:26 -0000
Message-Id: <200209010651.BAA24617@despammed.com>
I did this w/ 16C84 some years ago, ie a single slope a-d using an exponential RC ramp rather than an integrator.
The rc ramp was just an RC connected to a port pin. The comparator was 1/2 LM393.
I used a 3rd order poly fit to the exponential, w/ fit forced through 0, and a span of 0-2.5V
The results gave better than 10 bits measured accuracy with 16bit fixed point arithmetic.
It was hard work given microchip charge about 20c extra for an adc now....
Simon
