This video shows how to install an Arduino nano into your coffee machine so that it can only be used when you know the right code. Ideal for use in any appliance in a shared kitchen or house.

The company I work for bought this coffee machine for its employees to use in a shared project office kitchen. The kitchen is used by a lot of other companies, and as it’s only a domestic coffee machine it wasn’t long before it broke from over because the hundreds of people in office who passed though the kitchen every day were all using it.

I took it home to fix it and at the same time I installed this keypad which prevented the machine from working until the correct code was entered. Now only the people in my company know the code so it gets much less use so will last much longer.

I took the main control board. I found avoltage regulator which I could tap off, and I traced the zero vault connection to an empty connection point on the board. I wanted to interrupt the middle pushbutton signal with a relay.

The relay is controlled by this Arduino nano. I soldered 8 of the pins upright instead of downwards, so I could plug the keypad directly onto the pins of the Arduino.

I used a red and green LED to display to the user what the status of the keypad is. I had to place these on the back of the board so they could be seen when the board was mounted inside the coffee machine,

I took a couple of pairs from a core multicore cable to power the Arduino and to connect the relay to the pushbutton.

I removed the solder from 2 of the pins on the start switch. The relay had to connect in series with this switch.

As these pins keep the switch in place, I stuck it down with some CA glue/super glue to stop it coming lose in future.

The two pins I disconnected both made the same connection to the other 2 pins on the switch, so to put this in series with the relay.

I soldered the power cables onto the 12v side of the on board voltage regulator. This one is a 3v regulator and it was too low to power the Arduino, The nano has an on-board voltage regulator that I used. I routed these cables through an unused slot in the board for strain relief.

I drilled some in the board so I could use some supports to mount the board on when it was installed in the coffee machine.

I covered all the connections with a layer of hot glue. This helped to keep everything in place on the main circuit board that was tapped off of existing components.

I measured out where the keypad will be installed on the side panel I removed from the coffee machine earlier. I cut a slot for the ribbon cable of the keypad to pass through. I used a ruler and the rotary tool to cut this out. The Arduino was going to be mounted behind this keypad so the ribbon cable can plug straight into the board.

I measured and drilled a hole where the status LEDs will shine through. To combine the Red and Green LED I used an acrylic rod to carry the light though. I wanted the internal face of this to be as clear as possible to carry the light with little degradation so I used wet and dry sandpaper, starting at 400 grit and a dab of water and I worked up to 1200 grit to get a smooth finish on this end of the rod.

It was smooth but not shiny. I’d normally use a metal polish to get that final shine but I experimented buffing the end up on the envelope of some junk mail with a little water.

I had to keep it moving as the paper started to tear quite easily. But it worked quite well for what I needed. So I cut the end off to the right size and started polishing the other end.

As the rod was only about 5mm long at this point it was easier to drill a hole in some scrap wood to hold it in place whilst I sanded the end. I didn’t want this end of the rod as shiny as I wanted it to diffuse the light from the LEDs so I gave it a once over with 400 grit sandpaper and that was good enough.

I started to rough up the inside surface of the coffee machines side panel so I could glue some circuit board supports in place. I marked up where they needed to go and stuck them in place with some 2 part epoxy.

I positioned the keypad, peeled the backing off the adhesive and lined it up, One last measure to make sure it was straight then I stuck it down.

The LED and keypad was working but it wasn’t operating the coffee machine, the issue was I had put too much hot glue around the surface mount switch that I had cut the pins off and that was stopping the button on the front from being pressed.
So I cut the excess glue off of the switch and tired again.

This video is intended for educational purposes only. Any modifications made to your own equipment is at your own risk, and could invalidate your products guarantee. Modifying a products electrical and electronic circuits can cause fire in some cases.