The spinning dial

Second part of the digital-mechanical clock project

I recently purchased some stepper-motor / driver combos as part of my clock project. These units are easy to use. They not only run on 5V, they also interface quite well with 3.3V logic without a logic converter.

Today I started to measure and design some sort of clock dial test bench in FreeCAD so that I can write some decent software for hall-effect sensing, dial rotation, mechanical fault protection etc.

The print had some minor hiccups, but it would still work for testing purposes. After some scrambled egg on toast, I put everything together to run some code. Stepper motors are very useful when precise rotation is required, not that I would need precise rotation but since the design is going to be mostly open-loop, I decided for a stepper motor.

I took quite a bit of concession with the mechanical design aspects of this project. I tried to put a few gear mechanism in place, akin to a classic analog clock, but that's way out of my sphere of skills and I didn't want to create another analog clock that's driven by a microcontroller / RTC. I wanted to create something that is primarily a software driven clock, with a mechanical display, could also be used to display other information perhaps. While thinking about software driven design, I thought this would also help me explore a few different aspects of bare-metal embedded programming, such as...

• Panic handling
• Detection & recovery of mechanical faults
• Barebones async programming

Test bench working! I will open source the project once it can be called a clock.

22-12-2024