For my OnStep telescope mount controller (visit my [group][1] for more information.) This design is built around the Teensy3.2 and supports the most important features while keeping a small size. There are two stepper drivers (one for RA/Azm and one for Dec/Alt.) There's a power jack, fuse, and power switch connection. Additionally, there's a limit sense input (to stop the mount,) and a PEC sensor input. For connectivity there's a USB Port and one other device supported. That device can be a Bluetooth adapter (Bluetooth Mate Silver or HC05,) or an ESP8266/ESP-01 for WiFi. There's also a modular connector for an ST4 guider interface (with optional 5V power.) This strives for drop-in compatibility with my prior OnStep Mini versions so the 3D printed case/panels *should* still work. [1]: https://groups.io/g/onstep