load cell + ina128p not reading

Other Hardware Sensors
1

Hi ,
I got an ina128p and a kitchen scale.
I would like to weight stuff with it. The problem is I always get the same value from my analogRead. I tried with 2 different scales and eve tried to put the load cell back on the kitchen scale and it works. I think I am wiring the load cell wrong .
I always get analog read value of 18 or 19. It changes constantly between them.

The way I did it :

Load Cell S- ---- Ina128 2
Load Cell S+ --- Ina128 3
Load Cell V+ ---- Arduino 5V
Load Cell V- ------ Arduino GRN

Ina 1 --- 10k resistor --- Ina 8
Ina 7 ---- Arduino 5V
Ina 6 ----Arduino analog0
Ina5 ---- Arduino GND
Ina4 ---- Arduino GND

I wasn't able to find ina125 so I went on with ina128. I checked online for couple examples but according to ones I found I am wiring correct. Also the scale uses a 3.7V battery , so I tried to change the V+ to 3.7 but still it doesn't work.

I would appreciate any help

2

The datasheet seems to indicate that the ina128 must have a dual supply (± 2,5V min). It may not operate on a single supply.

3

Also, a resistor of 10K results in a gain of ~5. These load cells typically need a gain of ~500 to 2000 which would equate to a resistor of 100R to 25R. Being off by just a few ohms will result in the reading being underamplified or overamplified so you need to do a lot of fiddling in finding the right value.

4

You might look at this