Analog to Digital conversion using 18F452

Nov 24, 2009 5 Replies

We are using Fuel sensor of Capacitence level transmitter which takes input



24 volts and gives output as 4-20 ma. When I am converting 4 ma to 20 ma using 250 resistor, converting into voltages.


We are getting 10 values 4 ma to 5 ma ex: 4.1,4.2,4.3 etc..,



When we are converting to voltages and taking adc values, adc values are rapidly changing. I am unable to note the adc values.


Please help me from this problem.


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Google on op-amp amp/buffer or hire someone who knows electronics.

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Decaf Linnnix, Decaf!

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Keep a circular queue of N number of samples and then average them?

input

Or use only 4 MSB's of the ADC result... Oh, and a large capacitor (100uF) across the 250 ohm resistor to get rid of any noise.

Meindert

It's the same solution as for most electronics problems - use a bigger capacitor.

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