Unknown Domain

IDEA 3: The convincer

Using the car’s window washer to make the person realise it is spitting, after having been advised there was rain predicted and ignoring the system. Manipulating the person for their own good.

IDEA 2: Slam the door

This idea uses people to augment the clever home’s arsenal of tools, they become an extension of the system.

The system is able to manipulate the human into adjusting something in their environment to meet the system’s requirements.

An example of this would be using HVAC (pollen filtering) and lighting (white balance) with other stimuli to wind up the person into a bad mood causing them to storm off, slam the door and correct a fault with a latch or a wonky painting.


Useful resources on RS485:




Character module MCU

So I have been looking at electronics predominately today, I looked starting with the RS-422 line driver, which I think should be a Maxim MAX1483, so I will be ordering a couple to test out on a breadboard as they are available in a DIP package, unlike half the stuff out there. How are you supposed to prototype an idea or do DIY projects if there are no DIP package versions, I for one am not going to make a PCB, and I don’t fancy buying/finding a breakout board either, anyway…

Looking at what I need for a MCU to drive the character module, I would like a chip available in DIP and some kind of SMD. It needs to be Arduino compatible and there are also the following probable needs:

1x UART for RS-422 (via line driver)
2x 10bit ADC for hex Switches
2x Digital input for IR Photodetectors
1x Digital output for a status LED
2x Digital output for the stepper driver interface (1x direction & 1x step)

Thats a total of 1x UART, 2x ADC, 2x digital inputs and 3x digital outputs, the Arduino as I said in a previous post is more than capable of this however a prefabricated Arduino board, even a clone board is about £12 and that is just more than it needs to be as I don’t need USB, and even if it is cheaper I still need another PCB shield to sit on top of the Arduino that holds the other chips.

So here is a list of known Arduino compatible chips and their issues:

ATmega1280 – Used in the original Arduino Mega, and is just too expensive
ATmega2560 – Used in the current Arduino Mega, and is just too expensive

ATmega8U2 – Has no ADC
ATmega16U2 – Has no ADC
ATmega32U4 – DIP package not available (otherwise perfect).

AT90USB1286 – Too expensive

ATtiny44 – Doesn’t have UART or enough program storage
ATtiny45 – Doesn’t have UART or enough program storage
ATtiny84 – Doesn’t have UART
ATtiny85 – Doesn’t have UART

ATmega8 – Limited program storage
ATmega168 – Good
ATmega328 – Good

Looks like the best chip to power the character modules is an Arduino still but just without the big board, nice to know as it means I can just use an Arduino for now. Was that a pointless waste of 2 hours? Probably but what did I learn? What UART means, and more about the range of MCUs Atmel makes. I will choose between the ATmega8/168/328 depending on my programme memory needs vs cost as the 168 is the ideal medium, the 328 is expensive.

Electronics planning


I think it is important for there to be a interface on the master control unit so that it can be controlled without a computer when there are issues which require testing,

Go online – Listen for messages from computer
Go offline – Ignore messages from computer
Blank – Runs all modules to blank flap
Home – Returns all modules to flap zero
Identify – Blanks display and runs selected module to X (marks the spot)
Test mode – Instructs each module to perform test (output on module)
Demo – Runs random modules to random flaps
Config – Not sure what might need configuring yet

The interface will be based on a scrolling menu of options, so there will be up, down, left, right, select, back.

I suspect as this project will only need one master control board I will just use an Arduino Mega 2560 as it has a USB interface and is hackable, I could even be useful should I want to add new features. What might make sense is to use a shield rather than just leaving cables stuck in the header pins.

During the prototyping phase I will be using a Mercury Motor’s SM-42BYG011-25 from Sparkfun, it doesn’t look like the manufacturer still make this, however they sell a bunch of similar ones and it is a standardised stepper motor. Any bi-polar 1.8º step motor will suit.

Stepper driver
In the prototyping phase I will be using a Sparkfun EasyDriver (4.3) however as the original designer of the board explains on his website, the EasyDriver is really just a breakout board so it will be included with the MCU and other components on the character module’s PCB.

The circuit primarily consists of an Allegro A3967 which will be more than adequate for the needs of this project.

Photo detector
To detect the flaps passing I will be experimenting with a pair of photo detectors, on to sense flap zero and one to detect each flap passing, whether this will work I am not sure, but its worth trying. Right now I am prototyping with this optical detector from Sparkfun.

DIP Switch
For location programming I will probably use a pair of HEX DILs or Rotary HEX switches, however just to get an idea of how I might be able to use a voltage divider to sense values from the switch without using 16 pins per switch, I will be using this 8 position switch from Love Electronics.

Because Arduino’s are expensive it seems over the top to use one for the character module PCB and as other parts are SMD and using a EasyDriver would be expensive too, it would make sense to do a custom PCB with all the circuitry necessary to run the module. As I only know C based languages really I would probably prefer to use an ATTiny45/85/2313 if suitable as they can run proper C or the Arduino boot loader so I can keep the programming simple for my own benefit.

It will need two digital inputs, two digital outputs, serial TX/RX, and two analogue inputs for the DIPs, however it would also be convenient to have a status LED which could be used to indicate problems, or set to flash when in the identify mode, so the front would show an X for frontal recognition and the back would be flashing for back recognition when working on large panels of these modules.


Water/laser/plasma cut 0.8mm black anodised aluminium quote

They people I spoke to about the cutting of the black anodised aluminium quoted £1 per flap which is reasonable but then you have to buy material too and the original devices used plastic, by the looks PP 0.5mm

Stanford University Graduate School of Business

I found this amazing project using what appears to be Krone units from looking but its absolutely beautiful to watch.

Monument to Change As It Changes - Zambrano Hall - Stanford University Graduate School of Business

From the artist:

Read more: LA Times

Materials update

So after a load of looking at other materials again I am here:

Styrene – Brittle and carcinogenic when burnt

Polypropylene – Same as the original flaps

ABS – Single sided

Acrylic – Brittle

PETG – Extremely melty

Rapidform said to use 4D Model Shop as a resource for finding out what materials are available but buy else where, I have however found engineering plastics, the plastic shop and eSheet so I think I am okay on that front.

Cut Laser Cut had two new suppliers to look at Arjowiggins (Priplak range) and Bayplastics Ltd. However I think its obvious that PP is the right material, I just need to get the right grade, definitely going to harrass that VitaSheet bloke, I also got another couple of names out of Cut Laser Cut…

One last thing to look into:

Black anodised aluminium – I spoke a long time ago to a company called ML Fabcuts but I never pursued it to a quote. I will contact them, VitaSheet man and possibly Arjowiggins tomorrow.

Cut Laser Cut


I visited Cut Laser Cut today and spoke to a really helpful chap, who’s name I neglected to ask. We had a good chat and came to the conclusion that PETG/Mylar which Rapidform suggested was very melty, he also said ABS might work but the samples all had a smooth/rough sides, however showed me the above sample of sign writers engravable ABS which if double sided would allow me to etch the characters directly onto the flaps.

I could imagine a process of putting the sheet of ABS in once and etching, then flipping it and etching again, with a cut immediately after. The problem is that laser etching is expensive as it is a very slow process, and the material only appears to come in 0.8mm which is single sided and he didn’t know what it actually was branded as, however looking into it the material is supplied by Rowmark and is for sign-writers to do laser etched signs.

The material is essentially a white sheet laminated with black.

Metal pins

Today I spoke to James at RapidformRCA about this project, he suggested a technique of laminating three ultra thin sheets together all identical with the exception that the middle sheet would have anL-shaped space to allow the separate metal pins to be inserted rather than cut out. Using an MDF jig he suggested gluing the sheets together with the metal pins. I like the idea of this but it adds another level of complexity to an already complex design.

In the revised design where there are four pins on two central slots it would mean a U-shaped slot and pin which would be nice because one piece of metal could hold both sides of one sprocket hole and even have designed space to allow it to flex a little during installation.

I will investigate this but I think I prefer the plastic pins in one piece. It would solve my issue with having different grains on each side but would potentially triple the laser cutter time and require additional metal pieces, adhesives and assembly.