# Multiple unknown resistance calaculation

Hy,
i am a new user of arduino uno. I want to know how can i calculate the value of unknown resistances using multiple analogue inputs by an arduino.

and the main point is every resistance is unknown. I have also attached the Picture from which you can get an idea.

if any one can help me in this matter?

You can't - analog inputs are reference to ground , so all
Analog measurements have to be with respect to ground ( 0v) - you can't have " floating inputs". Why do you want to do this ? What are you really trying to do ?

i am working on integrated circuits. so i have to measure resistance between each leg of IC.

OPs posted circuit

Noraiz:
i am working on integrated circuits. so i have to measure resistance between each leg of IC.

Why?
I think you need to explain why you need to to measure the resistance of each leg.
What sort of ICs?
Can you tell us your electronics, programming, Arduino, hardware experience?
Tom…

If you connect one end of those resistor networks to GND and one end to 5V and analog inputs on the nodes, you should be able to calculate the in-between resistances as it's simply a voltage divider. Just make sure it's all linear, so the branched ones need multiple tests.

But then if it's an IC as you later reveal, the whole picture changes dramatically. Whether that is even possible depends on the IC itself. If it's a semiconductor it becomes even trickier - a diode for example has a voltage drop but no resistance: under it's threshold voltage the resistance is infinite, above that it's zero (for an idealised diode, of course, real world ones have leakage and a small resistance).

After that of course the question: why? What are you really trying to accomplish?

Well i am working on IC´s for the autonomous cars which is very new technology in a company of germany.
thats why its an internal structure of an IC which are being tested whether there is short circuit inside the IC or not. for this i need to measure resistance. i can also measure manually but it will take so much time. so thats why i want to make a prototype so it can calculate at once all the values.

Well, if you can indeed approximate as a series of resistors, it's still simply a matter of connecting one end of the series to Vcc and the other end to GND (add an extra resistor on both ends) and then connect all the mid points to analog pins, and calculate the resistance from there. Then it becomes rather straightforward, just a voltage divider.
Of course you can only do as many pins as you have analog inputs, which is not that many, so doing it manually is probably just as fast (shouldn't take more than a few seconds for each adjacent pair of pins).

Hi,

Well i am working on IC´s for the autonomous cars which is very new technology in a company of germany.
thats why its an internal structure of an IC which are being tested whether there is short circuit inside the IC or not

Will you be testing the IC's in circuit or removing them to test?

Can you tell us your electronics, programming, Arduino, hardware experience?

Tom....

its out of your capability to understand what i am actually experimenting. i dont need to give you my experience.

Noraiz:
its out of your capability to understand what i am actually experimenting.

That's a pretty arrogant statement, especially in light of the question you came with here, which is so basic (voltage dividers are part of my 11yo's electronics play kit) it makes me wonder whether YOU really understand enough electronics to know what you're trying to do - at least, what you say you're trying to do.

Hi,

its out of your capability to understand what i am actually experimenting. i dont need to give you my experience.

Will you be testing the IC's in circuit or removing them to test?

Tom...
PS. You need to read the side bar of the replies being posted to appreciate the experience of most of the people offering you advice. (And its free..)

Noraiz:
its out of your capability to understand what i am actually experimenting.

Bollocks.

If this is really an IC then measuring resistance with no power applied will look like diodes to ground. Measuring the resistance with power on the IC is meaningless. Measuring the impedance is another matter.

Obviously, this project is "out of the OP's capability".