Ideas for connecting to analog input of PIC

[ipunished]

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]

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]

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

 

[Miguel Gaspar]

What does the pic actually measures voltage or current and how it must be atached?

 

[ipunished]

@ 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

 

[Miguel Gaspar]

There is a one solution:


---------- Post added at 19:07 ---------- Previous post was at 19:07 ----------

Please let me know any other doubt

 

[ipunished]

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]

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.