shivg:
Also, I still dont know the common and differential thing with HX711 mentioned by Leo and Dave evans.
I know of opamp, common mode voltage: V(Inv)+V(NonInv)/2 & Diff Voltage: V(Inv)-V(NonInv)
How you derived 16.8 mV at 128 gain.Dave and Leo
The HX711 states on page 1 that the input voltage range at 128x gain is +/- 20mV.
Page 3 states a common mode range (the inputs have to stay within) of "GND + 1.2volt" and "AVDD -1.3volt"
So the working window is 5 - 1.2 - 1.3 = 2.5volt.
Full scale at 128x gain is 2.5volt / 128 = 0.01953volt. Close to the stated 20mV.
That's if AVDD is 5volt, but the boards/diagrams I have seen stabilise AVDD to 4.3volt.
That leaves a range of 1.8volt and a full scale of +/- 14mV. (must have made a mistake posting 16.8mV before).
Input range can be doubled by changing default amplification to 64x.
Leo..