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Ideas for connecting to analog input of PIC

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ipunished

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Hello,

I have written the code for it and now I want to actually make it work.

Its used to test or check resistance, and i am using a pic with analog input..

I was just wondering how to make that possible?

I know that I can drive a constant, known current through the resistor and then how do I connect it to the pic and how tio read it?

i was thinking differential amplifier but i dont think that will work....

anyone have any ideas on this?

Thank you
 

andre_luis

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The use of an OP-AMP or even an OTA is a good idea.
Make sure that resistance value applied don´t generate a voltage value that exeed rail range.

+++
 

klystron

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You must start of with a requirement for example to read the room temperature using a LM35 temperature sensor
 

ipunished

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@ andre,

I thought of using an op amp and also found this configuration **broken link removed**

but it does not explain much..

@ Miguel

the PIC is supposed to measure the voltage accross a resistor, and how it must be attached is what im asking :)
 

ipunished

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Thanks miguel, that is somewhat like the schematic i found in my link, can you give a bit more details on its working.. as in if im to make a schematic of this.. furthermore, how can it only take the value by just one connection?


Thanks
 

Miguel Gaspar

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By Ohms Law , if you have a current source of Ix value V = IxR
you must calibrate according the maximum value that accepts your PIC.

If your Vmax = 10, and your Rmax = 10K, Ix must be 10V/10K = 1mA so you can have a voltage proportional to the ohms of your resistence.
 

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