Weight sensor (Load cell)

Other Hardware Sensors
1

Hello,
I am using Arduino uno with weight sensor which uses 9V power supply. One can measure change in weight by mapping change in voltage across two wires. In my project I have given output of Weight sensor to Differential Op-amp (+12V and -12V) . The output of op-amp is given to analog pin of Arduino(A2 pin).
In multimeter if I see output from op-amp it ranges from 0V to 3V, but A2 pin always shows 1023.
Please help in troubleshooting the issue.

code is as follows

const int WS_Output=A2;

void setup()
{
Serial.begin(9600);
pinMode(WS_Output, INPUT);

}

void loop() 
{
   
 int WS_Input= analogRead(WS_Output);

 Serial.println(WS_Input);
}

Thanks in advance

2

Let's see the code....

(Use the </> icon above the :slight_smile: to format it as code)

3

Oh, and the circuit..... is there a common ground?

4

Yes, common ground between op-amp, weight sensor and arduino board

5 
const int WS_Output=A2;

void setup()
 {
Serial.begin(9600);
pinMode(WS_Output, INPUT);

}

void loop() 
{
    
  int WS_Input= analogRead(WS_Output);

  Serial.println(WS_Input);
}
6

the analog input is relative to the 3.3v ( or 5v) output. if analog input is 3.3v then you get 1023 if 0v you get 0. you could attach a resistor to the A2 and ground, that might help.

7

Anagal92:
In my project I have given output of Weight sensor to Differential Op-amp (+12V and -12V) . The output of op-amp is given to analog pin of Arduino(A2 pin).

You will probably damage your Arduino chip if the op-amp output goes outside the chip's input voltage range of -0.5V to Vcc+0.5V. If you have not already done so, as a minimum place a resistor, say 47kΩ, in series with the A2 pin to allow the chip's input protection diodes to work.