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If I am going to be using an External ADC for each sensor, then I guess do not have to connect a voltage to Vref for the PIC18F6520.
For example, If I choose the LM34 and connect this device to an external 8 bit ADC. What type of data will I be getting from the ADC, and how will I be able to decifer it on the PIC side?
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Depends on the ADC now doesn't it?Originally Posted by Srigopal007
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Using an external ADC.
Make all of the IO's digital.
This may get me in trouble but I am going to refer you to a Basic Stamp document.
http://www.parallax.com/dl/docs/books/edu/ic.pdf
Goto the section "Experiment #4: Continuous Process Control"
The Basic Stamp is built around a PIC but does not have ADC. The code is close enough to understand what is going on.
The above "Experiment #4: Continuous Process Control" is using a LM34 and a n ADC 0831.
If I told you how to do it, it would just be the same thing as in the document, almost. There are other good ideas there too.
Dave
Always wear safety glasses while programming.
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If you want accuracy, why not dump all the hardware and use the DS18B20? It has +/-0.5°C accuracy from –10°C to +85°C. And is purely digital interface. I think Bruce from www.rentron.com has examples for the chip.
Ioannis
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Ioannis,
The problem here is not with getting accuracy with using one sensor, the problem here is using multiple sensors and obtaining accurate data. but I think I will looking into the parallax that mackrackit suggested. I will post later with questions and comments. Thanks
-Srig
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So, you can use multiple 1-wire sensors scattered all over the place and connected through one-wire only (and ground of course).
I cannot see the problem.
You will get rid off the op-amps, ADC's etc and WILL have the 0.5 accuracy.
Ioannis
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