Packaging the twittering cat door

… the saga of the twittering cat door continues…

(you may find it helpful to refer to previous articles in this series : Twittering Cat Door and  Enhanced twittering cat door)

With the prototype working and tested, and a steady stream of tweets being produced by the cat, I’ve got to the point where I need to hide all the wires, and tidy up the physical installation. It has to look clean and professional, or I won’t feel that i’ve “finished” the job.

packaged

With this in mind, here are the criteria I have for success :

  • Arduino housed in a clean-looking box, wall-mounted.
  • Power, ethernet and USB ports all exposed through the box housing, so it can be connected, reprogrammed, and debugged in-situ if necessary
  • Reset switch mouted outside the box, so I can reset the machine if it’s not connecting to the message broker for some reason.
  • Red, Green and Yellow LEDs mounted so they are visible outside the box.
  • White, multi-wire cables to connect the unit with the external reed switches
  • Reed switches/door sensors to connect to the box using 3.5mm audio jacks, so connections look professional.
  • Internally to the box, electrical connections to be made to the arduino via wire soldered to header pins. The pins then slot into the arduino without damaging it
  • Should not over-heat with continuous use
  • Should have room to add extra sensors and actuators later

So, that’s the brief.

I ordered loads of parts from Rapid Components. I was all excited when it all arrived. Lots of little plastic bags with all the different pieces in.

Didn’t take long to drill holes for the LEDs, external push-switch, 3.5mm audion jacks. The case is a fairly hard plastic but a drill pushes through easily.

The LEDs and audio jacks were all mounted using the same mechanism : A screw-up ring rides a thread, allowing the component to be tightened against the inside and outside walls of the case.

For the external reset switch, This is connected to the RESET line on one side, and to GND on the other. I worried for a bit that an extra resistor was necessary for this to protect a short-circuit, but it seems ok for now.

I used an 8-pin row, and 6-pin row of header pins, soldered to small strips of strip-board. Wires were then attached to this, and connected to the case-mounted components. All the resistors are mounted on a separate strip-board. Each component is also connected to the resistor board, and a single wire from the resistor  strip-board runs back to the GND pin on the arduino.  The result is a bit of a “birds-nest” of wires, but each of the wires is long enough to let me open/close the case without problem.

Connecting the arduino board to the box was perhaps unconventionally done using double-sided sticky velcro pads. This means I can easily get the arduino out of the case when/if necessary.

I put a few extra holes on the edge near the power/ethernet just to make sure the arduino is vented, to limit the chance that it would over-heat.

packaged_detail

I have to put labels on the front really, so other people can understand the meanings of the lights.

The yellow light came in handy tonight too: It was dark in the room, I looked in the window and saw that the cat was in already without having to search for her.

Completed unit installed and connected:

packaged

Conclusions

As I’ve never done this sort of thing before, I had to plan what I was going to do fairly carefully, as I only wanted to place one order for components.

Physical packaging seems harder than all the other tasks dealing with the prototypes.

I hope you all agree,  it now looks the part.

Of course, this is massive over-kill for a cat door, but it has taught me a lot, and I’ve had loads of fun in the process.

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One Response to Packaging the twittering cat door

  1. Pingback: Twittering Cat Door « Cobweb

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