After nine months of modifying the OnStep open source telescope controller to run on the cheap STM32 ARM Cortex M3 microcontroller, it is time to reap the fruits of this long labour: I have an OnStep powered mount ...

Back in mid December 2017, I submitted to Howard the Hardware Abstraction Layer (HAL) to enable ports of OnStep to additional platforms in a modular fashion with less effort. Before the STM32 was completed, HAL proved useful in supporting RAMPS, Arduino Due, and lately the ESP32.

One of the obstacles in using OnStep is the process of configuring it. A user should start with a spreadsheet that calculates certain parameters. The user is supposed to check that they lie between acceptable ranges mentioned in the spreadsheet.