For my OnStep telescope mount controller (visit my [group][1] for more information.) This design is built around the Teensy3.5/3.6 There are four stepper drivers (one for RA/Azm, one for Dec/Alt, one for a focuser, and one for a rotator/second focuser.) All are available on RJ jacks at the PCB back. There's a power jack, fuse, and power switch connection. There are several connectivity options: USB, an I2C port (w/footprint for the DS3231 RTC.) There are two serial ports. Serial4 is brought out on a pin-header connector (w/power.) Serial1 is on a WeMos D1 Mini (ESP8266) foot-print for Wifi support. There is a D-Sub connector DB9 that has home SW inputs, PEC input, and two channels of A/B encoder inputs (which run to the ESP8266.) There's also a modular connector for an ST4 guider interface (with optional 5V power.) One a 3.5mm stereo mini jack is a limit sense input (to stop the mount) and also a reticule LED output. And finally, there's a mini speaker output for an alert buzzer. [1]: https://groups.io/g/onstep History Version 2.0 First release of MaxPCB2 Version 2.1 Moved PPS from DS3231 on 32KHZ to SQW pin Version 2.11 Silkscreen improvements, removed unused pads on RTC