Hi guys,
I am new to Arduino, and I am trying to make an ohmmeter. However, I will be able to conduct my project more efficiently if I can measure the resistance of multiple materials at a time using only one Arduino board.
Is there any way to do this?
I bought an Arduino shield (the input output Arduino shield) - is that the right way to go for this project?
Hope to get a response soon! :)...and happy new year!
An UNO can read 6 analogs referenced to GND.
These are read in sequenced at a high rate of speed.
What circuit do you have for the measurements?
.
I have only one resistor in my circuit....I am not really sure about how to describe it...what kind of description do u need?
Draw a diagram of how you think you are going to read this resistance.
Attach it here for us to see.
.
If you only have one resistor then you can not use the Arduino to measure its resistance.
You need a resistor from the analog input to 5V and then your unknown resistor from the analog input to ground. Then by measuring the voltage you can calculate the unknown resistor value.
Hi,
Welcome to the forum.
What is the range of resistance that you will be measuring in these materials?
Tom..... 
This is how to measure the resistance by using 2 resistors in series forms a voltage divider circuit.
//This is the code to make the arduino function as an ohmmeter
//This code will display the voltage that drops across the unknown resistor //along with its resistance
int analogPin= 0;
int raw= 0;
int Vin= 5;
float Vout= 0;
float R1= 1000;
float R2= 0;
float buffer= 0;
void setup()
{
Serial.begin(9600);
}
void loop()
{
raw= analogRead(analogPin);
if(raw)
{
buffer= raw * Vin;
Vout= (buffer)/1024.0;
buffer= (Vin/Vout) -1;
R2= R1 * buffer;
Serial.print("Vout: ");
Serial.println(Vout);
Serial.print("R2: ");
Serial.println(R2);
delay(1000);
}
}
The autorange circuit lacks a connection from Rx to the analog input.
