For someone who has never used stepper motors, real-time clocks, or built anything from scratch, [Dodgey99] has done a great job of bending them to his will while building his Etch-A-Sketch clock.
He used two 5V stepper motors with ULN2003 drivers. These motors are mounted on the back and rotate the knobs via pulleys. They are kind of slow; it takes about 2 1/2 minutes to draw the time, but the point of the hack is to watch the Etch-A-Sketch. [Dodgey99] is working to replace these steppers with Nema 17 motors which are much faster. [Dodgey99] used an EasyDriver for Arduino to drive them. He’s got an Arduino chip kit in this clock to save on the BOM, but you could use a regular Arduino. He left out the 5V regulator because the EasyDriver has one.
[Dodgey99] has published three sketches for the clock: one to set up the RTC so that the correct time is displayed once the Etch-A-Sketch is finished, some code to test the hardware and sample the look of the digits, and the main code to replace the test code.
The icing on this timekeeping cake is the acrylic base and mounting he’s fashioned. During his mounting trials, he learned a valuable lesson about drilling holes into an Etch-A-Sketch. You can’t shake an Etch-A-Sketch programmatically, so he rotates it with a Nema 17. Check it out after the jump.
If you’re paying attention, you’ll realize we just saw the exact opposite of this project a few hours ago: a CNC tool (laser cutter) controlled by turning Etch-A-Sketch knobs.