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Whiteboard Clock

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Re: Whiteboard Clock

#31

Post by m-ou-se »

agwa wrote: post #16
andars wrote: post #10

How do you go about setting up a custom device file like that (/dev/whiteboard)? Is it just writing a device driver?

The author says the device is a USB modem. So, under Linux, the author could have simply written a udev rule to use the name "whiteboard" for that particular USB modem's device file.

Indeed. It's just a udev rule with: SYMLINK+="whiteboard

Re: Whiteboard Clock

#33

Post by asd »

phogster wrote: post #32

Here's an analysis of how often you would have to change the marker on a similar clock: https://pay.reddit.com/r/theydidthemath/comments/2vky0v/requ...

The next step: Enhance design so clock can change its own marker.

Re: Whiteboard Clock

#35

Post by gxs »

Let's say someone wanted to learn how to do this. Not just follow a step by step guide, but actually learn how to do this. Where would you find a good resource?

Re: Whiteboard Clock

#36

Post by siglesias »

Using a home presence API (like Nest's), this thing could also abstain from updating the time until you were home or in the same room as it. That could dramatically reduce wear and tear.

Re: Whiteboard Clock

#37

Post by zild3d »

gxs wrote: post #35

Let's say someone wanted to learn how to do this. Not just follow a step by step guide, but actually learn how to do this. Where would you find a good resource?

This of course depends on what you know already (CS or EE background?), but the easiest way would be to use an arduino. You'd need to have some electronics knowledge (basic circuitry, servo motors) and be able to do some embedded programming (PWM, ADC/DAC, interrupts/timers)

Re: Whiteboard Clock

#38

Post by joshu »

gxs wrote: post #35

Let's say someone wanted to learn how to do this. Not just follow a step by step guide, but actually learn how to do this. Where would you find a good resource?

You would need to control a pair of servos. Arduino is the easy way. Some trigonometry to convert x-y positions to the two arm angles. The connectors to the pen are linkages.

I am currently building a whiteboard plotter myself, though a much larger scale.

Feel free to send me questions and I can send you pointers on where to research next.

Re: Whiteboard Clock

#40

Post by hugs »

joshu wrote: post #38
gxs wrote: post #35

Let's say someone wanted to learn how to do this. Not just follow a step by step guide, but actually learn how to do this. Where would you find a good resource?

You would need to control a pair of servos. Arduino is the easy way. Some trigonometry to convert x-y positions to the two arm angles. The connectors to the pen are linkages. I am currently building a whiteboard plotter myself, though a much larger scale. Feel free to send me questions and I can send you pointers on where to research next.

There are three parts to learn -- the electronics (handled by an Arduino and a few servos), the mechanics (for this design, it's not too complicated -- you could make do with popsicle sticks and some screws if you had to), and the software. The tricky bit with the software is the math. The arms, when free to spin around their centers, can be considered circles. You'd want to learn the geometry of circles and, specifically, how to find the intersection of two circles. The joints on the arms are where the circles meet.

I'm working a new version of my mobile testing robot that looks very similar to this clock. Haven't posted the code, yet, but I did have to go back and re-learn some trig and circle geometry to make the simulator. http://youtu.be/qRzrm4zx82g

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