Building a Force Plate: Hardware Problems

The first prototype used an Arduino Uno clone and an FSR402 pressure sensor. It proved the idea, but it also showed why that hardware was the wrong tool for measuring jump force.

Why the First Version Failed

The Arduino ADC had only 10-bit resolution, and the FSR behaved almost like a binary pressure switch. The OSB board flexed, the sensor position was fragile, and a long external cable made the whole setup unstable.

Current Hardware

• Eight 50 kg load cells: inexpensive bathroom-scale sensors for the first serious prototype.
• CS1238 ADC: 24-bit conversion and a much higher sampling rate than the popular HX711.
• ESP32: enough connectivity and community support, with a path toward BLE.

Wiring Lesson

The main difficulty was not the firmware, but the physical wiring: eight sensors become four bridge pairs, the bridge wiring then feeds the CS1238, and the ADC connects to the ESP32. It was my first real soldering-heavy prototype, and somehow it worked on the first power-up.

The companion software note is here: force plate software problems.