Arduino Weight Measurement using Load Cell and HX711 Module
Today we are going to Measure the Weight by interfacing Load Cell and HX711 Weight Sensor with Arduino. We have seen weight machines at many shops, where machine displays the weight just by placing any item on the weighing platform. So here we are building the same Weighing machine by using Arduino and Load cells, having capacity of measuring upto 40kg. This limit can be further increased by using the Load cell of higher capacity.
- Arduino Uno
- Load cell (40kg)
- HX711 Load cell Amplifier Module
- 16×2 LCD
- Connecting wires
- USB cable
- Nut bolts, Frame and base
Load Cell and HX711 Weight Sensor Module:
Load cell is transducer which transforms force or pressure into electrical output. Magnitude of this electrical output is directly proportion to the force being applied. Load cells have strain gauge, which deforms when pressure is applied on it. And then strain gauge generates electrical signal on deformation as its effective resistance changes on deformation. A load cell usually consists of four strain gauges in a Wheatstone bridge configuration. Load cell comes in various ranges like 5kg, 10kg, 100kg and more, here we have used Load cell, which can weight upto 40kg.
Now the electrical signals generated by Load cell is in few millivolts, so they need to be further amplify by some amplifier and hence HX711 Weighing Sensor comes into picture. HX711 Weighing Sensor Module has HX711 chip, which is a 24 high precision A/D converter (Analog to digital converter). HX711 has two analog input channels and we can get gain up to128 by programming these channels. So HX711 module amplifies the low electric output of Load cells and then this amplified & digitally converted signal is fed into the Arduino to derive the weight.
Load cell is connected with HX711 Load cell Amplifier using four wires. These four wires are Red, Black, White and Green/Blue. There may be slight variation in colors of wires from module to module. Below the connection details and diagram:
- RED Wire is connected to E+
- BLACK Wire is connected to E-
- WHITE Wire is connected to A-
- GREEN Wire is connected to A+
Fixing Load Cell with Platform and Base:
This step is optional and you can directly put the weights on the Load cell without Platform and can simply clamp it without fixing it with any base, but it’s better to attach a platform for putting the large things on it and fix it on a Base so that it stand still. So here we need to make a frame or platform for putting the things for weight measurement. A base is also required to fix the load cell over it by using nuts and bolts. Here we have used a hard cardboard for the frame for placing things over it and a wooden board as Base. Now do the connections as shown in the circuit diagram and you are ready to go.