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BinClock - Binary Clock Qball Style

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For the 2nd x-mas day I decided to make a clock. I recently (well already 1.5 years ago I build a nixie clock. We are moving building at work and one thing I miss in my current room is a clock. Bringing a nixie clock was my first idea, but it has some problems. Firstly it is expensive to build (especially the tubes that have a real 5 not an upside down 2), it has 170V running through it and relatively easy to access and it probably wears down pretty quickly when used 24/5.

So lets build something new, preferable with LEDs. But any clock won’t do, I had some ideas:

  1. . Binary Clock.
  2. . Non normal clock-face design.

Secondly I had some extra requirements:

  1. . The minimal number of components needed and wires. This so if I like it I can easily make a cheap PCB.
  2. . Possible show temperature.
  3. . PC interface, so maybe to use for notifications.

Clock Face

I had this idea for a binary clock face a while back, its simple and it is round (like a clock). The top part (yellow leds) shows minutes, the middle part (red leds) hours (1-12 h) and bottom part (blue leds) seconds.

Clock Face

I am pretty confident it will work out.

Hardware

As I said I wanted to use the least amount of components, basically:

  • 16 LEDs and 2 resistors for the display.
  • MCU (for now I took an Arduino I had lying around) plan to take an Cortex m0 later.
  • DS1820 temperature sensor and pull-up resistor.

Wiring

So I wanted the least amount of wires. So I re-used a trick I used several years back, to hook up LEDs. In this design I control 16 LEDs with 6 wires in total. Not sure hot to do it with less (without using extra hardware or LEDs with controllers build in).

Wiring

It is a 2x4 grid (4 columns 2 banks), Then we can double the amount of entries by reversing polarity. If it works in star-trek why wouldn’t it work for me. The software is a bit more tricky, you can only enable certain LEDs at the same time (I choose to have only one on at the same time) and you need 3 states: High, Low, Floating. Luckely this is something easy to do on an AVR. The required resistors are in the bank lines.

Wiring - ugly soldering

Casing

This is where things get tricky, LEDs have the tendency to be bright, very bright. To top that, the only LEDs I had in stock where ultra-brights. So I tried several solutions:

  1. . Shine through wood. An idea that I had for a while now, but never knew if it would work. I drilled a hole that almost completely through the wood except for the last 0.5 mm (and dried various other depths). This did not give the desired result. The best result gave a weird stripe with the ‘flow of the wood’. I knew it was a long shot. Maybe I find the right wood for this later.
  2. . Veneer. I did not have anything sufficiently thin to work.
  3. . Milk-glass. This worked very well, except that the off-state are hard to see. Making it hard to read the time. So some ‘labeling’ on the glass was needed.
  4. . Paper. This worked surprisingly well and gave a nice ‘look’. Especially with the next point added.
  5. . Deep hole. I sunk the leds in a 3 mm deep hole, This looks very nice when looking at it from a (slight) angle. The problem of brightness still remains when looking directly in it.
  6. . I have some more ideas in combination with 5. If I find something perfect, I will blog about it.

For now I went with method 5, in a small wooden box. This box once held a ‘Amphenol precision connector/APC’ and dates back from 1973 or so. I got a few of these from the trash at work. If I am going to make a PCB I will make a nice small case around it. (Could be a watch?)

I also included the temperature sensor half embedded in the back of the case.

Leds front

Software

The software can be found on GitHub. It is a simple arduino sketch, that uses lower level register access here and there to speed things up (and I am more used doing it this way). As said before, only one led can be turned on at the time, but quickly turning the required LEDs on and off I can create the illusion that any number of led is on. By playing with on/off time I can also dim them when needed.

API

There currently is a simple API for controlling things:

  • sHHMMSS Set time.
  • t Show temperature.
  • a Turn on all LEDs.
  • x Test sequence.
  • lX Set led on time between 0 and 255 (raw).
  • dX Set led off time between 0 and 255 (raw).

More to come.

ToDo

There is more to do, like with any project.

  1. Make a final version.
  2. Port to Cortex M0.
  3. Make small PCB.
  4. Get time via Wireless or DCF.
  5. Button to show temperature.

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