load cell The Load Cell and Weight Sensor HX711 will be connected to the Arduino to measure weight. The weight of an item is displayed by an automated weight machine in many shops. Users place the item on the platform and the machine displays the weight. Therefore, there is a weighing machine that has been built with Arduino and Load cells, which is capable of weighing up to 40kg. Further increase of the limit is possible by using more capable load cells.

Arduino Uno

Load cell (40kg) HX711 Load cell Amplifier Module 16x2 LCD Connecting wires USB cable Breadboard Nut bolts, Frame and base

Load cells are electronic transducers that create an electrical signal from force or pressure. Indirectly related to the force applied is the magnitude of the electrical output. During application of pressure, strain gauges in load cells deform. When the strain gauge is deformed, the effective resistance changes, so electrical signals are generated. Four strain gauges are typically used as part of a Wheatstone bridge to form a load cell. These load cells can weigh up to 40kg, and come in different ranges like 5kg, 10kg, 100kg and even more. Here, we are using a Load cell that can weigh up to 40kg. Because the load cell has an output voltage in the range of a few millivolts, these signals require further amplification, hence the HX711 Weighing

Sensor is required. An HX711 chip is used in the HX711 Weighing Sensor Module, which is an A/D converter with 24 high-precision channels. Two analog input channels can be programmed in the HX711 for gains up to 128 by programming them. So the HX711 module outputs the low electrical signal from the load cells which is then amplified and digitally converted before being fed to Arduino to calculate weight. Four wires are used to connect the load cell to the HX711 Amplifier. Red, black, white and green/blue wires make up these wires. Wire colors may vary slightly from one module to another. RED Wire is connected to E+ BLACK Wire is connected to E- WHITE Wire is connected to A- GREEN Wire is connected to A+

Weights may be applied directly to the load cell without the Platform step. Although the clamp can simply be attached to the plate without a base, a platform should be attached for putting large objects on it, which should be fixed to a base so that it stands still. Therefore, the frame or platform is necessary in order to place the weight measuring equipment. Furthermore, a load cell needs to be fixed to a base using bolts and nuts. The base is made out of a hard board, which has been covered with hard cardboard. Once the connections are made according to the schematic, you are ready to go.

Schematic and connections are provided below for this project. Pin numbers 8, 9, 10, 11, 12 and 13 of Arduino are connected to 16x2 LCD pins RS, EN, d4, d5, d6, and d7 respectively. Arduino's A0 and A1 pins are connected directly to the DT and SCK pins of HX711 Module. Circuit diagrams of the HX711 module and load cell connections have also been explained earlier.

It is easy to execute this Arduino weight measurement project. In advance of discussing details, this system needs to be calibrated for accurate weight measurements. A calibration process starts automatically when the system is powered up. In case the user wishes to calibrate it manually, he or she can use the push button. The following code describes how we created a void calibrate() function for calibration purposes. When calibrating the load cell, wait for the LCD display to appear once 100 grams of load is placed on the cell as demonstrated in the picture below. You should put the 100g weight over the load cell when the LCD reads "put 100g" and then wait for it to appear on the LCD. Upon completion of the calibration procedure, the process will take a few seconds. Any weight can be put over the load cell after calibration (maximum 40kg) and the calculated value will appear over the LCD in grams.

Arduino was used to manage the entire process in this project. HX711 Load Amplifier Module receives the weight signal from the load cell in the form of an electrical analog voltage. Using the HX711 ADC, a 24bit input signal is amplified, and then digitally converted into a 24-bit output, which is then fed to the Arduino. After the data from HX711 has been calculated by Arduino, the weight values are converted into grams and displayed on LCD. The calibration of the system is accomplished by pushing a button. In order to facilitate the process, we created an Arduino program.