Arduino cake

It was Aidan’s 10th birthday party on the weekend, so a birthday cake was in order. And what better subject than an Arduino Uno?

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This is a 3:1 scale model of an Arduino in vanilla buttermilk sponge, with coloured fondant icing (some dark chocolate was mixed in for the black components), royal icing details, and real (inedible) LEDs. Here it is from a few other angles:

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The USB type B socket, power socket, and ATmega328P are all separate blocks of iced cake attached with buttercream. The USB socket needed a couple of toothpicks to hold it in place.

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Four LEDs with long wires attached were inserted from the underside of the cake through holes made with chopsticks. These were driven from a real Arduino Uno running a simple program which simulated the flashing of the RX and TX lights during loading, followed by signalling “Happy 10th Birthday Aidan” in Morse code on the pin-13 LED on the board. See the video.

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The result was well worth it – one very impressed young man!

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Check out some of the other cakes we’ve done.

Fixing the Swan Teasmade backlight

We love our Swan STM100 Teasmade – two fresh cups of tea, in bed, whenever we want. But like many other people, we found the blue backlight far too bright – so bright it disturbed our sleep.

I got a bit tired of covering it up with a cloth every night. Here’s how I fixed it properly – the Gurunoia Teasmade backlight mod.

How to turn off the blue backlight on a Swan STM100 Teasmade

Note: this modification will void your warranty, can expose you to dangerous electrical voltages, and may ruin your Teasmade permanently. I’ve documented what I did to my machine here for information only – follow at your own risk.

The Teasmade is well put together and solid, but it seems to have rather more screws than strictly necessary. The module is a bit tricky to remove and replace, but everything else is straightforward. You’ll need a crosshead screwdriver, a craft knife, and a bit of patience.

1. Start by removing all 10 exposed screws from the base of the Teasmade. Then remove the base. All these screws are the same length.

2. Hold the Teasmade upside down with the clock facing away from you. Identify the large flat module that contains the clock, buttons, and controller. In a moment you’ll be sliding this out.

But first, slide out the thin rectangular grey heat shield between the boiling chamber and the module. You’ll need to flex it a little and push the wires out of the way to do this. It slides straight up.

3. The module is held in by two screws – one on top at the right, and one down the bottom at the left. Remove both screws. The two screws are identical, but different from the first set – they have a built-in flange.

4. Now very carefully slide the module up and out. This is a bit tricky, since you have to do several things simultaneously:

  • Flex the front panel away from the buttons (you need to use considerable force for this, but don’t use any tools or you may mark the panel).
  • Depress the buttons so they can slide up under the panel.
  • Slowly edge the module up on first one side then the other.
  • Unclip the module from the two screw posts from which you just removed screws.
  • Unhook the cable tie from the right-hand screw post.
  • Take care not to break the attachment of the delay-start button on the centre screw post as it slides past (although I did and it still works fine).
  • Take care not to lose the springs under the buttons (particularly the alarm-set and time-set buttons, which are not attached).

5. Undo the 12 screws on the clear side of the module. These screws are again identical, but different from the earlier screws. Swing the opaque plastic rear cover out of the way, taking care not to bend the components on the board as the cover passes them.

6. The clock face is backlit by four blue LEDs at the corners of the main board (KC-800-PC-V1.0). These are wired in series and controlled by a single transistor (TR2) driven by the microcontroller.

To disable the LEDs, all you need to do is break the connection anywhere in this chain. I chose to cut the trace at the top of the board, between the first and second LEDs. Use a sharp craft knife to cut through the green mask and the copper trace, into the fibreglass board. Go over it a few times to make sure it’s completely severed.

You can reverse this later by bridging the gap by soldering a wire across it (or across the nearest LED terminals, which may be more convenient), or you could try dimming the display rather than disabling it completely by using an appropriate resistor.

7. Replace the module cover and attach with the 12 screws.

8. Slide the module back in.

  • Make sure the buttons are in the right places. There’s a flat on the two smaller buttons to hold them in place – the bottom of the alarm-set button and the top of the time-set button.
  • Easing the clock back into position behind the panel may be tricky, since there’s a sharp metal surround in the panel. I used a credit card between the clock face and the surround to lever it into place.
  • Be sure to clip the module into both screw posts, and to hook the cable tie back over the screw post before you do so.
  • Screw it back in with two flanged screws.

9. Slide the heat shield back into place. Be sure the wires are kept as much as possible behind the heat shield, so they are not exposed to the heat of the boiling chamber.

10. Replace the bottom cover, taking care to fit the power cable filter and grommet correctly into the bottom cover. Attach with 10 screws.

You’re done! Power up and check everything still works. Result: a Teasmade you can leave on without disturbing your sleep, until it’s time for that trademark whooshing gurgle! The clock face is easily readable without the backlight, and anyway you probably already have a bedside clock.

Future enhancements

The delay-start button still has a bright blue LED behind it. A future mod will do something about that; for now just mask it with some tape or a filter behind the button.

It would be great to have the backlight just come on when needed – say when you pressed a button. Please post if you know how to reprogram the microcontroller (it says something like “Elan EM78P808BAAQJ 07307 BG07782” which is presumably the Elan EM78P808).

Please let me know if you try this. Comments and corrections welcome!

Pressure switch

Today’s bit of fun was fixing the PE error on our LG Fuzzy Logic 5.5kg WF-T552 3 step TurboDrum top-loading washing machine.

Apparently the PE error means there’s a pressure switch problem. The pressure switch is in the controller, but connected to the washer drum by a hose. Given that draining and wiggling it wasn’t working any more, and armed with the above information, a light, and a few screwdrivers, I bravely went once more unto the breach.

Here is the inside of the machine. Note the clear pressure hose at the upper right.

The switch is in the controller on top of the machine, and the hose runs down to the outside of the drum. There it meets a channel of some sort, which opens out at the very bottom of the drum like so:

Presumably there’s a blockage in the hose, in the channel, or in the opening at the bottom of the drum. To fix this, you don’t need to open any of the above! Instead, open the cover on top of the machine, like so:

The pressure switch is the component with the circular blue surround. It’s held in by three plastic retaining clips. The hose connects underneath it.

To fix it, I simply released the pressure switch, disconnected the hose, blew hard through it a few times to clear any blockage, and replaced it. We shall see over the next few days whether that is enough to solve the problem!

Update: It worked for a while, but the pressure switch was on the way out. I’ve since replaced it – very easy, and it only cost NZ$20.55. Yay! Big shout-out to Axial who were splendid in identifying and supplying the part.