3 Application Setup

A load cell is an electromechanical sensor used to measure force or weight. Through a mechanical arrangement, the sensed force deforms a strain gauge. The strain gauge measures the deformation as a change in electrical resistance. A load cell usually consists of four strain gauges in a Wheatstone bridge configuration. The electrical signal output is typically in the order of a few millivolts and requires amplification before it can be measured. The load cell is used in various applications, including weight scales.

Figure 3-1. Strain Gauge Load Cell and Wheatstone Bridge Configuration

The weight scale application is developed around the AVR16EB32 microcontroller and uses the Event System, the Timer/Counter type F (TCF) and the ADC peripherals to periodically sample the output signal of a strain gauge load cell. The resulting values are converted to weight and displayed on a Mikroe® OLED Click board and in the serial terminal window or the Data Visualizer (DV) interface.

Figure 3-2. Weight Scale Block Diagram