UC2-ESP: A general-purpose framework for open-source microscopy control.

Building the optical setup for investigating biological questions comes with challenges. A major such challenge is setting up and synchronizing the control of multiple hardware components such as stages, cameras and lasers. With UC2-ESP, we present a low-cost electronics system powered by the ESP32 microcontroller (∼$10), designed as an accessible, open-hardware alternative to commercial controllers for custom and open-source microscopy setups. Our system can interface with stepper motors, direct current motors, lasers (transistor-transistor logics, TTL or pulse width modulation, PWM), light-emitting diodes and analog voltage outputs (galvo mirrors and LED current control), allowing precise control over microscopy hardware. The platform is highly flexible, supporting custom pin configurations and multiple communication interfaces such as Bluetooth, universal serial bus (USB-serial) and HTTP via a built-in web server. A PlayStation controller can be used for haptic hardware manipulation, whereas commands are transmitted in a human-readable JSON format to ensure modularity and extensibility. The firmware is designed to receive parameters and execute actions dynamically, supporting complex control loops such as motor homing, stage scanning and temperature regulation via integrated controllers. Furthermore, the system integrates seamlessly with ImSwitch as well as Micro-Manager and offers a browser-based control tool using Web Serial. This open-source firmware enables microscopy research groups to develop custom setups and expand functionality efficiently, at low cost and high flexibility.