Nightlight Late-Night Edition

A 3D printable night light with Arduino-controlled LED light effects and a virtually arbitrary number of front designs (limited only by your creativity).
This project powers electronic components (5V) with a mains supply circuit (230V > 5V) that is connected to a power plug (230V). If you are going to build this, make sure that you know what you do. In case of doubt, consult a skilled person that is conversant with mains voltage or use a safe power source like a line adapter or batteries.

tl;dr A nightlight based on a reworked Thingiverse design with Arduino-controlled LED light effects, touch sensors, and a piezo buzzer humming the first notes from the Imperial march. Watch the video to see it in action. Detailed instructions start below video.

Bragging rights

The rocket nightlight was presented in the German MAKE magazine 06/2016 as a community project. Thank you! 🙂

The link or a click on the picture take you to the table of contents of issue 06/2016. If you have questions concerning this project do not hesitate to contact me! <foobar@zeropage.io>

Project Description

You can find a great design for a LED nightlight with various emblems or logos like Stormtrooper, Superman, Punisher, etc. on Thingiverse. This design is based on a 3D printed case with a transparent and extruded inlay of the emblem/logo in the lid. The case has a hole on the backside to have an external power supply feed the internal light source, e.g., an RGB light stripe or similar.

I reworked this design to create a nightlight that

  • does not need an external power supply, i.e., has a plug and can be directly plugged into a wall socket
  • has touch switches to easily adjust the brightness, light effects (or modes), colors etc.
  • uses a piezo buzzer to acknowledge touch switch triggers and to play the first notes from the Imperial March when plugged into a socket (a little annoying, but can be switched off;-)
  • utilizes a mounting platform for six RGB LEDs that can be easily inserted into the case
  • fixes some minor issues in the original design (displaced inlay and mounting hole)
  • comes with a variety of light effects like fixed colors, strobe, or cyclone chase

Payload

1 x Arduino Pro Mini 5V 16MHz // Merchants on eBay offer a plethora of pro minis. Take care when ordering: The pro mini is available as 3,3V and 5V as well as 8MHz and 16MHz versions. Moreover: Many vendors are located in China; shipping may take a long time to your home country.
1 x Piezo buzzer // One of these (eBay) should work.
1 x Power supply // I used this EMSA050120, 5 V-/1,2 A from Pollin to harvest the mains supply circuit and the plug.
4 x 3D printed part // These comprise a case, an LED holder, a plate with the emblem/logo. You will find the 3D templates as STL files on Thingiverse.
6 x RGB LED // The WS2812b have a nice color range and are usually cheapest when bought as an LED stripe. I had some spare LEDs from another project. You can order them on eBay or here (1m stripe, Roboter Bausatz Shop).
4 x M5, 16mm counter-sunk screw
1 x Software // The software for the Arduino is available in my Nightlight Late-Night Edition repository on GitHub.

Moreover a Dremel or similar to cut open the mains adapter, pliers, rasps, wires, some metal splints for the touch sensors, and, of course, a soldering iron.

Nightlight 3D Parts

The nightlight consists of four 3D printed parts; cf. the sandwich picture showing the different layers.

nightlight layer view

From bottom to top: 1) Case to host the mains supply circuit, Arduino pro mini, piezo buzzer, LEDs, touch switches, cables, and the plug. 2) LED holder. 3) The top plate and 4) the extruded emblem inlay.

3D Part 1: The Case

The case from the original design was only 13mm high (inner height) and, thus, not tall enough to host the electronic parts. I had to import the STL file into SketchUp and stretch the case on the z-axis to an inner height of 25mm. That gave me just enough space to squeeze the LED holder above the mains supply circuit into the case and still have 2 or 3mm distance from the top plate. The more space you have between the LEDs and the plate, the better the light will be diffused. But I did not want the nightlight to be more bulky than necessary so 25mm inner height had to suffice.

Increasing the height was the easy part. Designing the plug holder on the backside of the case was more difficult. I first measured the dimensions of the plug as precise as possible, then started to design a plug holder with SketchUp.

stormtrooper-nightlight-plug-measurementstormtrooper-nightlight-plug-holderstormtrooper-nightlight-plug-holder-prototyping

It took a couple of iterations and an according number of test prints until, finally, the plug snapped into the plug holder with a satisfying “click”. The plug fits so tight that I consider it to be unremovable without destroying the case. And I may add that this is by design since we are dealing with 230V AC power and the nightlight must be impenetrable by adventurous kid’s hands.

stormtrooper-nightlight-printed-case-mediumstormtrooper-nightlight-plug-holder-ready-medium

The case was printed with black REC PLA at 210°, bed temperature 60°, no support, 0.16mm height, 1.2mm wall thickness, and 66% infill. It depends on your 3D printer’s bridging abilities if the plug holder will be ok without support. If unsure, print the case with support turned on.

3D Part 2: The LED Holder

I wanted the LEDs in the nightlight to be on a planar surface to get an even illumination. The idea was to construct an LED holder in SketchUp that tightly fits into the case without gluing, is rather stable, and has legs to stand on. The images show what I came up with.

nightlight-led-holderstormtrooper-nightlight-led-holder-backsidestormtrooper-no-nightlight-led-holder-in-case2

Luckily, the LED holder nearly immediately matched all of the above mentioned criteria. I chose white innofil3D PLA for the print since a white background looked best behind the semi-transparent inlay.

3D Part 3: The top Plate

The plate was printed with black REC PLA and the same print parameters as for the case (210°, bed temperature 60°, no support, 0.16mm height, 1.2mm wall thickness) except that infill was set to 100%. I did not want any light to escape through the plate. With a proper number of top and bottom layers 100% infill with black PLA might be an extreme overkill but I played it safe.

nightlight-rocket-lidnightlight-rocket-3d-printed

With 100% infill the plate came out rock solid which has another advantage: Some parts might need to be sanded so that the extruded emblem/logo wil fit into the plate. The more solid your parts, the better they can be sanded.

3D Part 4: The Emblem/Logo

The extruded rocket inlay was printed with transparent innofil3D PLA. You will notice that “transparent” is in no way comparable to acrylic glass or alike. Moreover, parts printed with this PLA look yellowed; like they have been exposed for too long in the sun. Nonetheless, this kind of transparency is the best you can get with current fused deposition modelling (FDM) based desktop 3D printers and PLA. Nylon and other filament materials might yield better results but they are more difficult to print and handle.
Infill was set to 22%. You will see the honeycomb pattern, or whatever type of infill you chose in your slicer, with such a low infill value. But more infill also means losing transparency. I was fine with 22%.

Avengers assemble!

Let’s put the hardware together.

Complete the Plate

The transparent emblem/logo has to be merged with the plate. Depending on the design there might be a couple of “loose” parts from the plate print that need to be inserted into the emblem/logo first. Rasps and sanding paper are your best friend in this step since the parts will most likely not fit straight off the 3D printer. While 3D prints are usually pretty nice, there are limits to the precision you can expect from FDM prints. The rocket has only one loose part which is the round window. That one is pretty easy to insert. If not, rasp and apply mild force. Do not apply too much pressure to the small parts – they might break or damage the plate. If in doubt, sand more and re-try often. It will finally fit. If all loose parts are pushed in the emblem/logo you will want to merge the emblem/logo with the plate. That might need some sanding too. The small and tall middle wing of the rocket will most likely need some sanding. Be very careful since it can break off easily. Carefully push the transparent part into the plate. A vise or a hammer might come in handy, depending on how brave you are. This step requires patience

Disassemble the Power Supply

As mentioned in the Payload-section I used a very cheap EMSA050120 power supply from Pollin to harvest the mains supply circuit and the plug. The case turned out to be very intractable and successfully resisted my attempts to pry it open it with a screw driver or pliers. I could have tried to pop it open in the vise but did not want to risk damaging the PCB/electronics inside. Well, let’s mill it open – Dremel time!

stormtrooper-nightlight-power-supply-dremelstormtrooper-nightlight-power-supply-openstormtrooper-nightlight-power-supply-backside

Caveat: Always mill with safety glasses and use protective gloves. The picture is just for demonstration purposes. Milling plastic produces foul-smelling, and most likely toxic, fumes. Do it outdoors. The picture in the middle shows the mains supply circuit along with the plug. In the next picture you can see the backside of the supply circuit with the big L- and N-conductance pads on the right-hand side of the PCB.

Solder Wires on Plug

The plug will be connected with solid copper cables to the L- and N-conductance pads of the mains supply circuit.

There is an ongoing discussion whether 230V connections ought to be crimped or if they are allowed to be soldered. If you decide to solder make sure that a) the soldered parts are perfectly solder joined and b) voltage isolation in terms of the dielectric strength of the used materials, creepage and clearance has been considered properly.

Before we can solder the cables two small plastic bars have to be removed from the plug. I use pliers to simply break them off. After that I start to solder the cables on the plug’s connection pads (to the left and right of the middle screw). Or I tried because this turns out to be an epic soldering fail. I try a dozen times but can’t get the, sorry, GODDAMMIT cables to solder-join with the pads. The pads literally refuse to be soldered! But resistance is futile and a couple of search engine queries later I seem to be wiser: The pads are made of stainless steel which is pretty hard to solder with normal tin-solder. If not impossible at all. What I need is soldering fluid, something like this (Conrad).

stormtrooper-nightlight-plug-stegestormtrooper-nightlight-loetwasserstormtrooper-nightlight-pads-soldered

If you read the soldering fluid’s hazard notes, well, you do not really want to use this stuff: Serious chemical burns of skin and eyes, irritating to the respiratory system, and so on and so forth. Zinc chloride is no fun. Keep away from children! After some more failed attempts even with the soldering fluid I learned that the pads need much more heat to join forces with the cables than I was used from soldering usual electronics stuff. So, finally, I got two nice solder joints. FTW!

Drill Holes for Touch Sensors

stormtrooper-nightlight-drill-holes It is always a good idea to think before you act. And I wish I’d done that before printing the case since I forgot to add two 4mm holes for the touch sensors on the right-hand side of the case! Facepalm! Printing the case again just because two holes were missing was not an option. But we are not only apt with additive but also with subtractive manufacturing: I drill the holes with a 3mm wood drill and get a perfect diameter after some minor rasping. PLA is fairly easy to drill, e.g. compared to acrylic glass. But you may have to lift the drill from time to time to remove excess plastic. Wood drills are designed to automatically forward the excess wood to the top of the drill and out of the drill hole. When you drill PLA or other plastic materials it tends to melt and get stuck on the drill. The slower you drill, the better. Applying some drops of water or sewing-machine oil is said to help (not tried so far).

Connect Mains Supply Circuit to Plug

In this step we connect the mains supply circuit to the plug and fix the circuit in the case.

Voltage isolation: As already mentioned you will have to take care of proper voltage isolation when dealing with 230V. The pictures show how I did it but they do not claim to be a blueprint for proper electronic handling especially with respect to mains voltage isolation. I would suggest to use spacers to attach the mains supply circuit to the bottom of the case so nothing on the flipside of the PCB can touch the case. Moreover the whole mains supply circuit including the soldered wires should be isolated from the rest of the electronic parts which can easily be achieved by enclosing it with an additional 3D part. As always: In case of doubt, ask an expert!

First pop the plug into the case’s plug holder. Since the copper wires are pretty rigid it is a good idea to shorten and bend them properly before soldering the wires to the mains supply circuit.

stormtrooper-nightlight-plug-in-casestormtrooper-nightlight-plug-to-mainsstormtrooper-nightlight-mains-supply-attached

Solder the mains supply circuit’s L-conductance pad to the brown copper wire. Repeat with the N-conductance pad and the blue wire. Finally, attach the mains supply circuit to the bottom of the case. You can see the black and red 5V power supply cables on the left-hand side of the mains supply circuit. We will use these later to power the LEDs and the Arduino microcontroller.

Attach LEDs to LED Holder

stormtrooper-nightlight-attach-ledsI decided to use six WS2812b LEDs and arranged them on the holder in a pattern that showed the most even illumination level during my tests. In case you’re a Lumen junkie there is enough room to cramp more LEDs on the holder. The LED strips usually come with sticky tape on their backside so gluing them on the holder is easy. After that I used 0.15mm enamelled copper wire to solder the connections between the +5V, GND and DOut->DIn pads. Keep the soldering time short to avoid melting the LED holder! The enamelled copper wire is a little tricky to solder because of the enamel coating. I suggest to first remove the enamel, e.g., by applying some tin solder, and then solder the wire to the LED pads. It’s more difficult the other way round. BTW: There is really no need to use enamelled copper wire. It looks nice but using them was more about aesthetics than function. Moreover, the enamelled copper tends to break at the solder joints. I recommend litz wire with a small diameter – easier to solder, less risk of breakage, same function.

Prepare the Touch Sensors

stormtrooper-nightlight-touch-sensors This nightlight requires two touch sensors to control its various functions. The Arduino library ADCTouch makes it very easy to add touch sensors to a project. You can connect nearly everything that changes its capacity when touched to an arbitrary analogue pin of the microcontroller and have that thing act like a touch sensor. In this project I use two small metal splints that will be stuck and glued in the drilled holes on the right-hand side of the case. To connect the splints to the Arduino I have to solder wires to them. Since they are made of stainless steel, I have to use soldering fluid again. One drop on each splint, plenty of heat, a little tin solder, and some heat shrink tubing later the two touch sensors are ready.

Wire it up!

The Fritzing breadboard view shows how the electronic components are wired up to the Arduino pro mini.

stormtrooper-nightlight-breadboard-view

You can choose different pins on the Arduino by adjusting the Arduino Sketch accordingly.

  • +5V from the power mains supply circuit goes to the VCC pin while ground is connected to the GND pin on the Arduino.
  • The piezo buzzer’s negative pole is connected to the GND pin, the positive pole to pin 12.
  • The upper touch sensor goes to pin A0.
  • The lower touch sensor goes to pin A2.
  • The view shows symbolically only one LED, not the wiring of all six LEDs. The first LED’s Din is connected via a 220 Ohm resistor to pin 10. It is usually advised to use a resistor to cover power spikes that could harm the LEDs. VSS or +5V on the LED is connected to the VCC pin on the Arduino. VDD or ground on the LED is wired to the a GND pin.

That’s how it looks like when all components have been soldered and put into place in the case.

stormtrooper-nightlight-everything-wired

Regarding voltage isolation: The 5V and 230V components should be properly isolated from each other. An additional layer that encloses the mains supply circuit and separates the 230V wires from the rest of the circuit is currently work in progress.

I used hot glue to paste the Arduino and the piezo buzzer on the case. The touch sensors were easier to attach with super glue.

Light and Diffusion

We need to diffuse the light that is emitted by the LEDs so that the transparent rocket is evenly illuminated. I already had some experience with diffusion materials from another project where I tried normal paper with different grammages, frosted acrylic glass, and Ripstop. The results were ok, but not perfect. I followed a hint that white baking paper yields good diffusion results. Unfortunately, I was not able to find white baking paper; only the usual brown one. Next I tried sandwich paper (sic!) and that’s what I found to work best when it comes to LED light diffusion. Of course, it depends on what you are building and especially, how much space there is between the LEDs and the material of the boundary layer. Try different materials and find the one that best suits your needs. However, I like the sandwich paper and, thus, taped a double layer on the backside of the plate. After that, the plate is screwed to the case with four black M5x16mm counter-sunk screws. I wanted screws with no imprint on the screw head but did not pay (enough) attention to the seller’s pictures on eBay. So, always take a very close look at what you intend to buy. 😉 NB: The screws have to cut their way through the holes in the case so it can get tedious to get them in. Use appropriate force. Moreover, the screw heads were bigger than expected so I had to widen the reception holes on the lid’s front side with a hand countersink.

Code is Poetry

All that hardware does not do anything without the proper software. We need a sketch (aka program) for the Arduino pro mini so the nightlight will do the things described in the project description. Two of the used libraries are worth mentioning: The awesome FastLED library to control the RGB LEDs. And the ADCTouch library to easily turn a cable or a splint into a touch sensor. The sketch makes use of the Arduino’s inbuild non-volatile EEPROM to store modes, colors, and other stuff that can be reloaded the next time the nighlight is powered up. The most complicated part of the code is handling the touch sensors. Both sensors react to short (1st function), middle-long (2nd function) and long touches (3rd function) and trigger different functions depending on the touch durations. Sounds complicated, but is not. Or is it?

Upper sensor

  • Short touch. Increase brightness of LEDs until maximum is reached (17 steps). Then turn LEDs off.
  • Middle-long touch. Immediately return brightness to lowest setting, i.e., one step above zero.
  • Long touch. Toggle playing Imperial March on power-up on/off.

Lower sensor

  • Short touch. Change color, speed, or whatever of current lighting mode.
  • Middle-long touch. Switch to next light mode.
  • Long touch. Immediately switch to first light mode, i.e., fixed color.

You can find the code in my Nightlight Late-Night Edition repository on GitHub.

Ready Player One

That was a real fun project and the roket nightlight turned out to be a full success!

Sep 2016, i.f.

Lord Overhaul fixes a rake’s missing wing nut

A lost wing nut is no reason to buy a new rake. Neither is an evil coarse pitched screw. Swap the screw, print a wing nut, and fix it!

Our rake lost its wing nut that is used to fix the pusher for the blades.

Rake repair lost wing nut

On first inspection I thought, that I just take any other M5 wing nut and that thing is good for another ten years of gardening service. But far wrong. The ISO metric screw threads (Wikipedia) come in different pitches: fine, middle, and coarse (at least in Germany). The thread in the rake must be either middle or coarse. At least none of my fine nuts fits on the thread.

So what now? Make or buy? Buy a couple of wing nuts? Buy a new rake? Of course not. Let’s replace the screw with a M5 fine pitched one.

the screws

First step: Pry open the lid. Done. Second step: Remove the old screw. Not an easy task since the manufacturer first drilled a hole and then pushed or hammered the screw through the hole so it stuck really, really tight. After a couple of miserable attempts to remove it with pliers I realized that there is only one appropriate tool for this job: A hammer. The evil screw is out.

Lid and evil screw

Let’s see how we get the new screw attached to the lid. Soldering stainless steel is difficult. Welding would surely work but is somewhat impossible without weldering equipment. Last resort: Glue! Hot glue, not durable enough. The same might apply to super glue. But two-component power putty should be fine.

rake-repair-power-puttyrake-repair-putty-toprake-repair-putty-bottom

Funny thing: I do have nuts, but no wing nuts! Duh! So let’s print a wing nut using the awesome Ultimate Nut Knob Generator (Thingiverse) by wstein. Here it is.

rake-repair-wing-nut-toprake-repair-wing-nut-bottomrake-repair-wing-nut-with-washer

I super glued a washer on the outer side so the PLA will not be squashed or damaged when the wing nut is tightened. Now it’s time to put the pieces back together.

rake repair - all parts ready to be assembled

Avengers assemble!

Rake repair done

All set and done. Let the gardening begin!

Spool holder attached to Ultimaker

Ultimaker 2+ Low Friction Spool Holder with Bearings

Stop squeaking, jamming, and under-extrusion! Use this Ultimaker low friction bearing based spool holder to cancel noises and add real Jesus gliding action!

Original spool holderThe spool holder shipped with the Ultimaker2+ is ok and with the new extruder there should be no issues with underextrusion. Depending on the size and type of the filament spool you might encounter squeaking noises from time to time. Surely not serious enough an issue to substitute the spool holder. But what if a spool does not fit on the spool holder and gets completely jammed? That’s what exactly happened with a spool from REC. Time for a new spool holder!

sneakypoo designed a nice bearing based Low friction spool holder and put it on Thingiverse. Thank you! The spool holder requires five 3D printed parts together with two bearings, a threaded rod and a couple of nuts. It comes in two different lengths for big and not so big spools as well as two different diameters to either fit 626 or 608 bearings.

I printed the short 608 version which is sufficient for standard 750g filament spools. The holder is very well designed and everything fit perfectly. Except the spacer which was too long so I had to rasp it down by approximately 4-5mm. A couple of commenters already pointed that out on Thingiverse. So trust them (or me, or all of us) and shrink the spacer in your slicer prior to printing!

The following picture shows the order in which the parts have to be assembled.

Spool Holder all parts

The assembled spool holder.

Assembled spool holder

And the new spool holder attached to the Ultimaker.

spool-holder-all-new

Check sneakypoo’s video to see what low friction looks like in real life. Awesome!

That thing is virtually noiseless and gives real Jesus gliding action. Luv it!

TopCraft Elektro-Tacker tackert wieder

Ein alter TopCraft-Tacker tat nicht mehr. Wenn man genügend viele Gene aus der Danger-Seeker-Sektion besitzt, kann man am Sicherheitskontakt rumpfuschen.

Requisiten-Typ: “Hey Scrooge! Ich krieg’ das Geweih an der Maus nicht fest!”
Scrooge: “Hast du’s schonmal mit ‘nem Tacker versucht?”

Herrlich böse!

topcraft elektrotackerAber zur Sache: Der alte Voltcraft-Elektrotacker wollte nicht mehr so richtig. Nach kurzer Inspektion war der zu schwergängige Sicherheitskontakt am Tackernadel-Ausgang als Übeltäter identifiziert. Das Gerät schoss nur noch manchmal und ohne erkennbares Muster. Sehr nervig, wenn man 100 mal drücken muß, bis endlich eine Nadel rauskommt.
Erstmal aufschrauben und schauen, was sich da machen lässt. Ergebnis: Zu wenig mit überschaubarem Aufwand. Also kurzerhand den Sicherheitskontakt entfernt, Kabel zusammengelötet und Gerät zusammengeschraubt. Jetzt ist wieder jeder Schuß ein Treffer. Ach ja, hundsgefährlich ist das natürlich auch. Aber gut für die Zombie-Apokalypse geeignet (solange Strom in der Nähe ist).

Liebe Kinder. Macht sowas nicht! Niemals. Ich darf das, weil ich ein, äh, erfahrener Maker bin und insbesondere, äh, weiß was ich tue. Aber ihr dürft das nicht. So ein Elektro-Tacker ist schon ohne Mod ziemlich gefährlich.

Resistor box on wall mount

3D printed resistor storage box with wall mount

Bring order and stability to your Maker country and get those lounging around resistors into an appropriate 3D printed nifty little resistor storage box.

Quite some time ago I ordered five E12 series resistors that I received in a plethora of plastic bags. One plastic bag for every resistor value. And since there are 12 resistors in each series, I had 60 plastic bags with resistors ranging from 10 Ohm to 820 kOhm lying around. That is the antitheses of orderliness and usability.

Browsing Thingiverse I came across this nice little resistor storage box.

Storage box and drawer STL

Each box has 12 drawers to hold all resistors from one E12 series. Printing five (actually six with a test print) boxes and 60(!) drawers was a lengthy process.

Resistor storage boxes and drawers

The result is ok. Though deliberately choosing a low print quality for the drawers (=less printing time) combined with warped backsides of the boxes required some reworking with a cutter blade and sanding paper. I use super glue to stack the boxes on top of each other and put the resistors into their drawers.

Putting resistors into their drawers

The drawers have a 17x6mm cavity at the front that can be used as a label field. Labeling the drawers is mandatory since there is not much sense in putting resistors into drawers without knowing which resistor has which resistance… Drawer label fieldUnless, of course, you like to compare the color rings with a resistor color table. It would be an interesting idea to build a simple Arduino-based auto-ranging ohmmeter and attach it to the top or bottom of the storage box phalanx; note to self for a later project. A label writer with 6mm tapes helps in creating and easily attaching the labels. Another solution would be to print, cut, and glue the labels. Hand writing might be an option, or you could even 3D print the labels which would be yet another fine Sisyphean task.

Now that the drawers have been labeled and all resistors are stored in their according drawer we have to think about where to place the resistors. When simply put on a table it will be hard to read the resistances of the drawers at the bottom of the stack of boxes. Moreover, the drawers can easily be pushed and pulled which is good for accessing the resistors but bad if the stack of boxes is jerked and the drawers start to slide out by themselves. Or, even worse, the box gets knocked over and spills all resistors on the table and floor. In order to properly read the labels I would like to attach the stack of boxes to the wall at eye level. And I want the boxes to be slightly tilted upwards so the drawers will not slide out by themselves.

Let’s create a wall mount with SketchUp!

Resistor box wall mount 1

Resistor box wall mount 2

You can download the STL file here. The next picture shows the box holder screwed to the wall. The holder looks distorted but this is due to the chosen perspective for the photography.

Resistor box wall mount

Finally, the stack of resistor boxes is super glued to the holder. Major achievement: “order and stability in our [resistor] country.”

Resistor box on wall mount

“Resistance is futile!”
i.f.

Coffee mill 3D printed funnel

Lord Overhaul repairs the coffee grinder’s broken bean hopper

How to repair a bean hopper's broken funnel using a sliding caliper, underdeveloped CAD skills, and a 3D printer. Funnel fun to the extreme!

Broken Coffee Grinder Bean Hopper My coffee grinder’s outlet experienced some sort of non-graceful degradation due to 50% operating error and 50% faulty design: A screw that was intended to fix the bean hopper to the coffee grinder’s base crushed into the outlet and broke it. In the aftermath of this unhappy event pieces started to brake away from the bean hopper’s outlet impairing its functioning.

What now? A new bean hopper would cost about 20,- €. Pretty expensive, and, BTW, where is the fun in that? “Stay back boy! This calls for divine intervention! … I kick ass for the Lord!” – Father McGruder from Brain Dead, 1992. Time for Lord Overhaul’s sliding caliper, some CAD (Computer-Aided Design) Voodoo, and a 3D printer to make a spare funnel for the bean hopper!

I use the caliper to measure a couple of things to get the dimensions of the funnel as exactly as possible. The most measurements are quit simple being either diameters or lengths. There is only one measurement that is a bit trickier: The correct slope of c is crucial for the funnel to neatly adapt to the bean hopper. The length of c can be measured easily, and a is the difference between the diameters of the outmost circle and the one beneath it. Since I can not measure the height b reliably, Pythagoras’ theorem comes to the rescue to calculate b. Confer the picture for an incredibly detailed and clearly arranged sketch. LOL

Bean Hopper Funnel Dimensions

Now for the fun part: I need a 3-dimensional digital representation of the funnel and nearly immediately fail to design an according shape in SketchUp. A fool with a tool is still a fool! In other words: Non-sufficient skills in a) CAD and b) SketchUp. Back to school, YouTube is your friend. After viewing some SketchUp howto videos about funnel drawing I came across this one by Ivor O’Shea.

Ivor describes a method using an outline and the “follow me” tool. After some trial and error I could finally come up with an outline for the bean hopper funnel that looked like it could work.

Coffee grinder sketchup drawing

Picture one shows the outline of my funnel with the dimensioning derived from the hand-drawn sketch (click picture to enlarge). I erased all snap lines drawn with the tape measure tool for clarity. Nonetheless, you definitely need snap lines for this method. In picture two you can see the “follow me” tool in action. The circle on the ground is only needed as a helper for the “follow me” tool and can be erased afterwards. By following the outline around the circle to a full 360° we get a complete funnel; cf. picture three.

Coffee mill 3D printed funnel SketchUp exports to STL which is then loaded into the slicer who in turn produces the *.gcode file that is sent to the 3D printer. After only two failed 3D prints due to wrong slicer settings and issues with warping and elephant foot the third print was successful. A nice black funnel that looks like it could fit perfectly on the bottom of the bean hopper. But before the funnel can be attached the bean hopper needs some precision work: The mortal remains of the old funnel need to be removed.

I first use a ripsaw to cut off the protruding parts of the old funnel from the bean hopper. Then I use a cutter blade to remove bumps and edges to get an even surface. Finally, I remove small ridges with sand paper. Coffee grinder is ready for new funnel There is nothing I can do about the cracks or the gap where a big chunk from the old funnel broke off; click the picture to enlarge, remains of the old funnel can be seen on the right. So, the bean hopper has been sufficiently primed to receive his new funnel!

Many tinkerers swear by either hot glue or superglue. So do I. With hot glue I would run the risk of filling up too much so I decide on superglue since I want the funnel to stick as tight as possible on the bean hopper. The 3D printed funnel fits perfectly and, with the amount of superglue used, will stick for all eternity. I carefully remove any excess superglue since I do not want superglue particles in my ground coffee and let the glued joint dry for some time before applying the repaired bean hopper to the coffee grinder.

coffee-mill-attached-funnel-3coffee-mill-attached-funnel-2coffee-mill-attached-funnel-1

Pushing and pulling the new funnel proves that superglue really lives up to its name. Let’s see if all the measuring was worth it!

coffee-mill-attaching-new-funnel-1coffee-mill-attaching-new-funnel-2coffee-mill-attaching-new-funnel-3

Oh, ah, Alpia. I love it when a plan comes together! The new funnel sits perfectly in the coffee grinder. Let the grinding begin!

i.f.

CD holder featured image

CD storage for kids with acrylic cover and exchangeable background

Looking for a good storage solution for your CDs or DVDs? Then welcome the acrylic glass MDF panel arbitrary background picture CD holder. Not only for kids.

We had a plan: Let us organize all those music and audio book CDs with two CD storage car sun visors. Pull them out, push them in, very easy! The reality: Yes, pulling out is easy. But no, putting them back tidily is complicated. Virtually impossible. Ok, no difference to the other stuff that is taken out of boxes, drawers, or shelves and scattered to the four winds. 😉 So let’s face reality: The plan failed!

It’s time for a different storage solution.

Project Description

Take a wooden panel. Put a nice picture on the panel to increase the CAF (children’s acceptance factor) as well as the CF (coolness factor) alongside the SOF (show off factor). Cover the picture with a 2 mm acrylic glass plate. Stick about two dozen CD glue dots made of rigid foam on the acrylic glass to act as CD holders. Hang the CD holder on the wall in the children’s room. Put the CDs on the glue dots. See what happens.

Payload

1 x MDF (medium density fiberboard) panel 1188 x 420 x 3 mm
1 x acrylic glass 1188 x 420 x 2 mm
1 x spray paint, white, silk mat
2 x wooden strip 2400 x 14 x 14 mm (used 3104 mm)
1 x sanding surfacer
8 x 3D printed clamp to hold acryl glass on MDF panel

Wood glue, screws, sanding paper.

Howto

Rasterbated figure for CD holder The picture mentioned in the project description will be made up of four printed DIN A3 sheets. The dimensions of one DIN A3 sheet are 42 x 29,7 cm. Putting four sheets beneath each other results in the target size of the MDF panel being 118,8 x 42 cm. We use The Rasterbator to create a PDF photomaster from the picture I’d like to use. The picture to the right shows the resulting four DIN A3 sheets.

Since the CD holder will have to be mounted somewhere it must not be too heavy. Thus, I decide on a 3 mm MDF panel. Thin as it is, the MDF panel is unstable so I will assemble a frame made of 14 x 14 mm wooden strips on the backside. This frame will a) stabilize the construct and b) allow easier installation of the CD holder to a wall or wardrobe.

Take a look at the 3D drawing to see how the frame is attached to the panel; click the picture to enlarge. I also added the exact dimensioning: Since the wooden strips are 14 x 14 mm I decided to indent the frame 14 mm on each side of the panel. That should give some kind of a floating impressions when the CD holder has been mounted.

CD Holder panel and frame

The MDF panel is 118,8 x 42 cm. Thus, we need two wooden strips with a length of 116 cm (118,8-2*1,4) and two with a length of 36,4 cm (42-4*1,4). The four parts are pre-drilled, glued and then screwed together. After that the frame is glued to the backside of the panel and additionally fixed with woodscrews on the front side.
Screw not sunk in I screwed them in without pre-drilling which was a mistake since the MDF is so dense that I was not able to sink the heads of the woodscrews into the MDF. All Screw sunk in screws looked more or less like the one shown in the picture. Steep learning curve. 😉 The screws must not stick out like this since they are on the front side of the panel where we need a planar surface to attach the DIN A3 sheets. Rework: I let the glue dry, remove the screws, post-drill the holes to a diameter roughly the size of the screw’s heads and, finally, sink the screws into the panel. There you go!

Next step: Use surfacer to fill the screw holes and smoothen the visible parts of the frame for spray painting. After applying the first layer of surfacer it has to dry. Afterwards everything gets sanded. One layer was not enough to get a planar surface on the sunk screws so I applied a second layer of surfacer on the screw holes. Sanding again. Since I did not want to win the 1st prize in a surface sanding and smoothness contest I moved on to spray painting the (visible parts of the) panel with silk mat white spray paint. It was a very good decision to do that in the garden! Spray paint everywhere, especially on the grass surrounding the panel. Would have been an even better idea to wear a dust mask… For a first time sanding and spray painting job the result is quite presentable.

CD holder sprayed front and back

When the paint has dried it’s time to hang the panel on the righthand side of our wardrobe. I consider a couple of possibilities to attach the panel and finally decide on the most direct method: Use four screws to screw that thing to the wardrobe (with pre-drilling the holes). Since the frame did not completely stabilize the MDF panel this is the minimally invasive method I can come up with to have the panel stick to the wardrobe as tight and close as possible. As soon as the panel is mounted and I start to attach the rasterbatorized DIN A3 sheets I realize that it would have been much easier to attach them before the panel was mounted. Too late. I use double-faced adhesive tape, usually used for photo books, to stick the sheets one by one to the panel. Here is what it looks like.

CD holder with attached picture

While the 3mm MDF panel was very cheap, just 2,79 € at the local hardware store, I had to search for quiet some time to find a dealer that sells the acrylic glass with dimensions 1188 x 420 x 2 mm for less than 30,- €. Acrylic glass is not that expensive in standard sizes but pre-cutted acrylic parts are, unfortunately, high priced. Now that the acrylic glass had been delivered, how to attach it to the MDF panel? I could drill holes and screw them together. Or I could use glue to tie them together for all eternity. But what if we would like to change the picture? Screwing takes time. Glue sounds to final. I thought that clipping or clamping the MDF and the acrylic panel together should be the best way to go and was, again, scouring the Internet for appropriate parts. After trying the Rapesco Supaclip 40 (too thin, too sharp-edged) and this pretty rare large slide clip (too big) I decided to design and 3D print the clamps on my own.

After exactly measuring the thickness of the acrylic-glass-paper-MDF-panel stack with a sliding calliper I constructed a clamp using SketchUp. Two test prints later I had ten ideal sized clamps that locked the acrylic glass snugly into position on the MDF panel. Here’s the 3D drawing of the clamp and a picture of 8 of the 10 printed clamps (PLA); click to enlarge the 3D drawing. The STL file is available for download.

CD holder clamps

We are ready for the final assembly stage: Glue dots and CDs! You will find a lot of offers for 16mm diameter CD glue dots on eBay, e.g., here. They are available in different colors but black and white prevail. It took a bit of thinking and patience to evenly distribute the glue dots over the acrylic glass plate. The CDs should have the same space between each other and to the sides of the panel. Tricky, since the glue dots stick like hell. No chance for trial and error. The result would not pass remeasurement but it’s ok from a distance.

CD holder glue dots and CDs

In the picture you can see on the left-hand side the CD holder with attached acrylic glass plate using the clamps. Second to left a couple of glue spots. Second to right 15 attached glue spots and 14 CDs. Rightmost picture: This is it! The finished CD holder with a full cast of 27 CDs. Click picture to see a bigger version of the final result.

Yes, you will not be able to gloat over the nice picture in the background. At least not if the CD holder is full to the brim. But design is about form that follows function. Right? 😉

i.f.

RIBB@TACKING Bruce Lee – a C64 game tribute and homage

Bruce Lee homage and art project: A 3D rendered picture from the C64 Game "Bruce Lee" in an Ikea Ribba frame with Arduino magic for a cookoo's clock effect.

One day end of 2015 I stumbled upon some pretty kewl voxel art by Metin Sevin. Amongst many others like Mario Bros, Pacman, or Donkey Kong, I was immediately fascinated by the 3D rendered Bruce Lee Commodore 64 game tribute picture. I contacted Metin and asked him if his work is for sale and he kindly pointed me to society6 where a lot of his art is available in various formats. If you are interested in Metin and his work you can find out more in this interview at the end of this blog post. Due to some other planned projects based on Ikea Ribba frames I had one 23x23cm frame on stock so the 8″x8″ Bruce Lee art print would fit just fine. Shipment from Illinois/USA took about two weeks and I was ready to go for my art project!

tl;dr Watch the video to see what this project is about. Making of with gory details below video.

Project Description

Take the 8″x8″ Bruce Lee art print and put it in a 23x23cm Ikea Ribba frame. Use an Arduino to play the C64 Bruce Lee game title music at 12am and 7pm. Announce every hour starting with the first 3secs of Carl Douglas’ Kung Fu Fighting song and indicate the current hour by an according number of Yamo’s calls (the green Sumo in the game). Announce a quarter past, half past, and a quarter to with the Ninja’s stick strike sound ringing out once, twice, or thrice, respectively. Finally, add a capacative touch sensor to cycle through all Bruce Lee game sounds by touching one corner of the Ribba frame.

Payload

1 x 8″x8″ Bruce Lee art print from society6.
1 x RIBBA frame from Ikea
1 x Visaton K28.40 8Ω, Price comparison idealo
1 x Arduino Nano e.g. from eBay
1 x LM386 Audio Amplifier Module e.g. from eBay
1 x DS3231 Real Time Clock (RTC) e.g. from eBay
1 x CR2032 battery for DS3231 RTC
1 x SD Card Module e.g. from eBay
1 x SD Card 1GB is sufficient
1 x 5V 1A power supply

Cables, solder and iron, hot-melt gun, screws, (cordless) screwdriver, drill, side cutter, etc.

A 1GB SD would have been sufficient since the WAVE files are very small. Unfortunately, I threw away old small capacity SD cards years ago “…when should I ever need a one or two GB SD card again?” Well, now I know the answer. Thus, I had to use an 8 GB SD card.

Audacity will be helpful to recode the Bruce Lee tunes to the required format.

Howto

Order the Bruce Lee voxel from society6. Wait approximately two weeks until it arrives; might heavily depend on where the item is shipped to. 😉 While waiting: a] Buy a 23x23cm RIBBA frame at your local Ikea. b] Prepare the necessary electronics and code to get the thing up and running.

Hardware

For the hardware part: Glue the required components, i.e. Arduino Nano, amplifier, SD card module, DS3231 RTC w/ CR2032 battery to the back of the RIBBA frame. It might look like this.

RIBBA frame with electronics

NB: This was my first shot with the loudspeaker directly glued to the backside as can be seen in the photo. My assumption that the – sort of abyssal – RIBBA frame will act as a good resonator
WAS WRONG. When I hung up the picture on the wall for the first time you could barely hear anything. The loudspeaker radiating directly to the wall was nearly completely muted since the sound waves cannot escape the frame.

Bruce Lee project Visaton SpeakeNew solution: Drill a plethora of holes into the bottom part of the frame and attach a (smaller) loudspeaker so that its sound waves can go through the holes. There are roughly 3 cm space between the backside (with the components) and the wall-facing side of the frame. Thus, I needed a speaker with a radius of max(3cm). I found an fairly good sounding 2,8x4cm rectangular-shaped speaker from Visaton that would fit snuggly into the available space (cf. picture).

Speaker drilling templateI created a drill template with the speaker’s exact dimensions by laying a piece of paper on top of it and tracing its contours with a pencil. Old school but works! After that I drew a mesh pattern with a lot of drill holes. That could have been the maiden trip for my drill press…but I went with the cordless screwdriver that did a nice job on drilling the 90+ holes. The template was fixed with sticky tape to the frame before drilling. I covered the whole template with tape to avoid frayed drill holes. This worked pretty good on the template Speaker drill holes burring done side but not on the inside of the frame. The RIBBA frame is made of chipboard so I lost quiet some material while drilling. You can see in the picture that the inside is not flat anymore but sort of curved due to the lost material. Next time I would apply sticky tape to the inside too.

After drillingThe holes needed some afterwork, i.e., burring and removing frayed pieces. The pictures do not show the final stage of afterwork so you will have to trust me that the result was ok. Especially, since the holes are on the bottom side that will, most likely, hardly been seen or looked at when the frame is hanging on the wall. I was happy with the result and moved on to screw the Visaton speaker into the frame with four black and tiny flat-head screws that were giving me a hard screwing time.

This is how the final setup looks like.

Visaton speaker attached

Note the blue cable going to the upper left corner?

This is the capacitive touch sensor wire. Capacitive touch sensor wire It is basically a piece of zinc coated copper wire bent to a 90° angle and sticked exactly to the corner of the frame using super glue. It was then painted black and soldered to the blue cable to have it connected to the Arduino. With this switch I would later be able to play all Bruce Lee game tunes one after another by repeatedly touching the bottom left corner of the frame. Actually, the ADCTouch-Library used is doing such a great job that the Arduino can react to a finger (or a hand, or some other body part) just coming near to the wire. You can measure changes in the wire’s capacity without even touching it. Awesome!

What’s missing? Yes, details on the wiring. The correct wiring might be hard to find out by just looking at the pictures, not least since my wire color scheme is a bit, eh, inconsistent. So here’s a Fritzing breadboard view of the wiring.

Bruce Lee RIBBA frame hanging on wall

That should cover the most important aspects of the hardware. But all this hardware is nothing without software. Let’s move into the matrix.

Software

Code is poetry

There are more lines of code in the Arduino sketch (GitHub) than needed to implement the behaviour as described in the Project Description. Nonetheless, some of the code is helpful for debugging purposes and some other for fiddling with the TMRpcm Library.

This library is used “for asynchronous playback of PCM/WAV files direct (sic!) from SD card”. The WAVE files must be in a specific format, i.e., 8-bit, 8-32khz Sample Rate, mono. Thus, do not expect Hifi quality! I wrote a separate article WAV-Dateien von SD-Karte mit Arduino abspiele where you will find the gory details about the required file format, how to convert, e.g., an mp3-file using Audacity into this specific WAV-format, how to format the SD card – if required, how the WAV-files have to be named on the SD card (8.3. SFN – short file name from the good ol’ MS-DOS times), and a short Arduino sketch to test the TMRpcm lib.

The ADCTouch library is required for utilizing capacitive touch sensors without any additional hardware.

Debugging with “Serial.print()” is not that funny so we’re using the Streaming library to provide a C++ like << operator that allows constructs like Serial << F( "Current volume is " ) << gVolume << "." << endl; which is very convenient. NB: With the macro F() you put strings in an Arduino's flash memory instead of the sparse static RAM (SRAM) leaving more space for variables and such. The ATmega328 chip found on the Uno has the following memory:

Flash  32k bytes (of which .5k is used for the bootloader)
SRAM   2k bytes
EEPROM 1k byte

Flash is plenty but SRAM isn't - so there is reason to always save SRAM!

Finally, we need the DS3232RTC and Time library to handle the real time clock. Europe will not let go of the daylight saving time (DST) idiocy. Summer time is switched on at the last Sunday in March where 2 o'clock becomes 3 o'clock. Vice versae at the last Sunday in October where 3 o'clock becomes 2 o'clock. We have to recognize the DST so the Bruce Lee cookoo works both in summer and winter. 😉 Thanks to user "jurs" from the German Arduino Forum we have a great European daylight savings time calculation function fIsSummertime() that returns "true" when we're in summer time and false if not.

The Arduino sketch

Sketch also available on GitHub in the RIBBAttacking-Bruce-Lee repository.

Interview with the artist

Metin and I had a nice e-mail-chat while the project was ongoing. There are quiet some analogies in our CVs like being born in the 1970s, growing up with 8-bit computers, adjusting the datassette's azimuth with a screwdriver, hanging out at arcade halls, and - of course - liking minimalistic pixel graphics. Here is short interview with Metin to get you in touch with him as a digital artist and his voxel creations.

Metin, who are you?
My name is Metin Seven, I was born in the 1970s, and grew up in the 1980s with the first 8-bit and 16-bit generations of game consoles and 'home computers', particularly the Atari 2600, CBS ColecoVision, Commodore 64 and Commodore Amiga.

What is your artistic spectrum, i.e., what kind of art do you make/prefer?
I'm a die-hard digital artist. I used to draw on paper as well, but I prefer the flexibility of the digital screen. I started creating pixel art for Amiga demos in the late 1980s. That soon evolved into creating pixel graphics for commercial games, television commercials and children's animation series in the 1990s, all done using software like Deluxe Paint and Personal Paint on an Amiga. Since the late 1990s I've shifted towards 3D graphics creation, but pixel art will always keep a special place in my heart.

Why retro games and what is your reference to this genre?
Ever since I was a little kid I was enchanted by the magic glow of the digital screen. I used to hang out at arcade halls, playing the first 8-bit games, such as Donkey Kong, Lady Bug, Pac-Man and Pengo. When I was not playing them myself, I could stare at people playing the games for hours. The first pixel graphics had this pure, iconic quality because of the low resolution restrictions for sprites and such. It's great to see that atmosphere return in the current wave of minimalistic pixel art games for mobile devices.

Did you have decent experiences with the C64?
Definitely. During my school days I spent just about every afternoon and evening playing Commodore 64 games, first loading them using the Datassette tape recorder, adjusting the azimuth when necessary. After a while I bought a floppy disk drive. LOAD "*",8,1 😀

How did you come to create voxel pictures? Where does the idea come from?
During the 2000s I created a lot of stylized 3D illustrations for printed magazines and newspapers. My use of shapes and colors reflected my game pixel art background, and gradually my illustration style became more elementary, until I arrived at a point that fully made sense — a blend between pixel art and 3D artwork: voxels. It was then that I decided to start paying tributes to my childhood love: 8-bit and 16-bit games.

Can you tell us something about the voxel creation process?
My first voxel images were created in 3ds Max in the mid-2000s, extruding blocks of quadrangular polygons. That was quite a hassle, and I was eager to find a dedicated voxel editor. I found that in the shape of Paint3D for Windows. I got in touch with the coder and suggested a number of features, which he kindly implemented.

When I switched to Mac OS X in 2014, I started using Qubicle, also a versatile voxel editor. I guess MagicaVoxel would be the tool of my choice today, but to be honest I've become a bit saturated when it comes to voxel creation, although there’s a good chance I'll return to it some day.

Where should we go if we'd be interested in more from you?
The best starting place is my portfolio site metinseven.com, there you will find links to my online shops, offering 3D prints, 2D art prints, stock 3D models and stock illustrations.

Many thanks for this interview, and my sincere compliments to you regarding your clock creation based on my voxel tribute to the classic 8-bit Bruce Lee game.

The pleasure was all mine! Keep on the good work!

Bruce Lee RIBBA frame hanging on wall

i.f.

Lautsprecher

WAV-Dateien von SD-Karte mit Arduino abspielen

Musik und Geräusche mit einem Arduino abspielen? Kein Problem mit dem guten alten WAVE-Format, einem SD-Kartenleser und der TMRpcm Library.

Arduino WAV Musik SD-Karte Eins gleich vorweg: Hifi-Qualität darf man von der hier beschriebenen Lösung nicht erwarten. Aber als Low-Budget-Player für einfache Zwecke reicht es auf jeden Fall. Habe ich beispielsweise hier im Kunstprojekt RIBB@TACKING Bruce Lee – a C64 game tribute and homage verwendet.

Was man braucht

Natürlich einen Arduino; der hier beschriebene Aufbau wurde mit einem Uno getestet. Alle 328er basierten, also auch Nano, LilyPad, Pro etc. sollten gleichermaßen funktionieren.

Da die WAVE-Dateien irgendwo abgespeichert sein müssen, bietet sich ein SD Kartenleser an. Es gibt Breakout Boards mit Micro-SD-Karten Slot oder andere Shields, auf denen solch ein Slot bereits integriert ist, bspw. das Ethernet-Shield. Hier kommt ein sehr einfacher 1 EUR SD-Kartenleser von eBay zum Einsatz. Dazu eine (alte) SD Karte.

Damit man etwas hört, braucht es einen Verstärker. Bryan beschreibt in diesem Blog-Artikel, wie man mit einem einzigen Transistor nebst Widerstand (4,7 kOhm) einen simplen Verstärker zusammenschustert. Der BC548B hat nicht ausreichend verstärkt. Mit dem 2N3904 (eBay) macht es mehr Spaß.

Dazu natürlich ein Lautsprecher, da hatte ich noch einen mit 0,25 Watt 4 Ohm auf Halde liegen.

Verkabelung / Aufbau

Die Anbindung des SD-Kartenlesers erfolgt über die Hardware SPI Pins des Arduino. Welche Pins das genau sind, hängt vom Arduino-Typ ab. Die hier gezeigte Verkabelung sollte für alle 328er Typen (Nano, Uno, etc.) funktionieren. Chip Select ist frei wählbar; vgl. auch der weiter unten stehende Arduino Sketch. Die Schaltung auf dem Breadboard ist der erwähnte Ein-Transistor-Verstärker. Wenn man hier den Widerstand zwischen Arduino-Ausgang (Pin 9) und der Transistorbasis zu klein wählt, kann man nach kurzer Zeit auf dem Transistor Eier braten, da zu viel Strom durch die Collector-Emitter-Strecke fliesst.

Arduino-WAVE-Player-Steckplatine-Breadboard-450x345

Wagemutige können den Widerstand einfach mal ganz weglassen und sich an einer, dann, recht ordentlichen Beschallung nebst Transistorheizung erfreuen. Das sei hiermit also ausdrücklich nicht empfohlen.

Kartenleser PINArduino PINWas ist das?
GNDGNDGround
+5V5VVolle Power! 🙂
MOSI11DATA, MOSI DATA, SDA, Hardware MOSI
MISO12MISO, Hardware MISO
CLK13CLK, SCL, Hardware SCK
CS4CS, Chip Select
GNDGNDGround

In der Tabelle ist die PIN-Verkabelung noch einmal aufgeführt. Der verwendete SD-Kartenleser hat zwei GND-Anschlüsse und funktioniert auch nur zuverlässig, wenn tatsächlich beide mit Masse verbunden werden. Der Lautsprecherausgang ist, ebenso wie Chip Select, über den Arduino Sketch frei wählbar (hier PIN 9).

Zwei Blog Posts haben bei Verkabelung und Inbetriebnahme gut geholfen. Zum einen dieser Beitrag bei maxoffsky.com sowie insbesondere diese Anleitung auf instructables.com.

Format der SD Karte

Die verwendete SD-Library unterstützt prinzipiell die Dateisysteme FAT16 und FAT32. Es wird jedoch empfohlen, wenn möglich, FAT16 einzusetzen. Bei mir hat’s mit einer FAT32-formatierten SD-Karte nicht funktioniert, daher wollte ich sie “mal eben” auf FAT16 formatieren. Das geht auch mit MacOS Bordmitteln, ist aber etwas komplizierter, als erwartet. Dieser Post im Adafruit-Forum beschreibt den Weg in Englisch; hier in knappem Deutsch:

  1. SD-Karte in den Mac stecken.
  2. Terminal-Fenster öffnen. Bspw. mit CMD+Space, dort “terminal” tippen und Return.
  3. Geräte-ID finden. Dazu im Terminal df gefolgt von Return eingeben. Es erscheint eine Filesystem-Übersicht, die unter anderem die folgenden Informationen enthält. Ganz unten ist die SD-Karte “NO NAME” zu sehen. Wer auf Nummer sicher gehen will, gibt seiner Karte einen eindeutigen Namen. Dann kann man sie in dieser Übersicht schneller finden. Die in den folgenden Schritten benötigte Geräte-ID lautet /dev/disk3s1.
    Filesystem        Used Available Capacity   iused   ifree %iused  Mounted on
    /dev/disk1   909007896  65197032    94% 113689985 8149629   93%   /
    devfs              371         0   100%       642       0  100%   /dev
    map -hosts           0         0   100%         0       0  100%   /net
    map auto_home        0         0   100%         0       0  100%   /home
    /dev/disk3s1     20928   4172608     1%       512       0  100%   /Volumes/NO NAME
    
  4. SD-Karte unmounten (nicht auswerfen!). Im Terminal diskutil unmount /dev/disk3s1 gefolgt von Return eingeben. Dabei disk3s1 natürlich durch die eigene Geräte-ID ersetzen. Erfolgreiches unmounten wird bspw. mit Volume NO NAME on disk3s1 unmounted quittiert.
  5. FAT16 Filesystem auf SD-Karte schreiben. ACHTUNG! Der folgende Befehl löscht alle Daten auf dem Gerät. Wenn die Geräte-ID nicht die von der eingesteckten SD-Karte ist, sondern bspw. aus Versehen die der eingebauten Festplatte, dann wird diese gelöscht. U have been warned.
    Folgendes Kommando im Terminal eingeben und nicht vergessen die Geräte-ID anzupassen. newfs_msdos -F 16 /dev/disk3s1
    Ich habe alle Warnmeldungen, die der Befehl produziert hat, konsequent ignoriert und als Lohn der Mühe im Anschluß eine lauffähige FAT16-formatierte SD-Karte gehabt.

Format der WAVE Dateien

Die Library TMRpcm benötigt zum Abspielen die WAVE-Dateien im Format acht Bit, acht bis 32 kHz Sample Rate, mono. Im WIKI zur Library werden zwei Wege beschrieben, wie man iTunes oder Audacity verwenden kann, um aus dem musikalischen Quellmaterial das Zielformat zu generieren. Audacity ist prima, und so geht’s damit:

  1. Hauptmenü “Tracks”, dort “Stereo Track to Mono” wählen.
  2. Unten links die “Project Rate (Hz)” mit dem Popup auf 8000, 11025, 16000, 22050 oder 32000 setzen. Je niedriger die Sampling Rate, desto schlechter die Qualität.
  3. Hauptmenü “File”, dort “Export Audio…” und im File Selection Dialog unten als Format “Other uncompressed files” wählen. Dann “Options…” klicken und als Header “WAV (Microsoft)” sowie bei Encoding “Unsigned 8-bit PCM” wählen. OK.
  4. Datei mit “Save” speichern.

Dateinamen

Dateinamen müssen zwingend dem – aus alten MS-DOS Zeiten bekannten – 8.3-Format folgen, also maximal acht Zeichen für den Dateinamen gefolgt von Punkt und einer Endung mit drei Zeichen beispielsweise “NAME0001.EXT”. Der Dateiname kann kürzer als acht Zeichen sein, in keinem Fall aber länger. Die Wikipedia widmet dem 8.3 short filename (SFN) tatsächlich einen eigenen Artikel.

Arduino Sketch

Der folgende Sketch bindet zunächst die benötigten Libraries ein, definiert Chip Select- und Lautsprecherausgangs-PIN, initialisiert die SD-Karte mit SD.begin() und spielt im Erfolgsfall die Wave-Datei snakec16.wav direkt von der SD-Karte ab. Im Fehlerfall wird eine kurze Meldung über den seriellen Monitor ausgegeben.

Wenn alles läuft…

…dann sollte das in etwa so aussehen, wie in dem Video.

Musik © Snake Charmer (Synapsis) / CC BY-ND 4.0

OLED 0,96″ Zoll Display an den Arduino anschließen

OLED Displays für den Arduino sind beliebt. Ein kurzer Wegweiser durch Anschluß-Pins, Protokolle und Libraries, damit das Mini-Display auch etwas anzeigt.

Bei eBay, Aliexpress & Co. gibt es zahnlose Mini-OLED-Displays, beispielsweise für den Betrieb an einem Arduino. Dabei sind die gängigen Größen 0,96 Zoll und 1,3 Zoll mit Auflösungen von 128 x 64 oder 128 x 32 Pixeln. Die Displays sind selbstleuchtend und werden in weiß, blau, gelb, Kombinationen davon oder auch “full color” angeboten. Die Full Color Displays stellen dann üblicherweise 65K Farben dar.

Es werden unterschiedliche Kommunikationsprotokolle unterstützt, in der Regel entweder I2C oder SPI oder beides. Dazu kommen unterschiedliche Driver Chips, für die die richtige Library benötigt wird, um das OLED ansteuern zu können. Gängig und gut unterstützt ist der Driver Chip SSD1306, der u.a. mit den folgenden beiden Libraries angesteuert werden kann: Adafruit_SSD1306 (github) oder U8glib (github). Wer ein OLED mit SS1106 Driver Chip erwischt hat, kann es mit der SH1106_SPI Library (github) versuchen.

Dieser Post zeigt den Anschluß und Betrieb eines einfachen, weißen 0,96″ Zoll OLED Displays (eBay) mit SSD1306 Driver Chip und sieben Anschluss-Pins an einen Arduino Uno. Nano, und alle weiteren Modelle mit ATmega328 Pinout, dürften auf dieselbe Weise angesteuert werden können. Im Zweifel das Datenblatt des Arduinos zu Rate ziehen.

Im folgenden Video ist das OLED im Einsatz zu sehen. Die Chord-Animation ist von Hari Wiguna, sein Kode steht auf GitHub bereit.

Um ein OLED erfolgreich ansteuern zu können, ist die richtige Verdrahtung zwischen Arduino und Display wichtig. Dabei wird es durch die Tatsache, dass die Displays mit unterschiedlicher Anzahl und Beschriftung der Pins geliefert werden nicht einfacher. Die Libraries erlauben üblicherweise die Verwendung von Software oder Hardware SPI, wobei letztere Variante deutlich schneller ist. Hardware SPI erfordert mehr Anschluss-Pins als Software SPI.

OLED AnschlussArduino PINWas ist das?
GNDGNDGround
VCC5VVolle Power! 🙂
D013CLK, SCL, Hardware SCK
D111DATA, MOSI DATA, SDA, Hardware MOSI
DC6Data/Command
DS7CS, Chip Select
RES8Reset

Das im Video gezeigte 0,96″ Display ist zur Ansteuerung durch Hardware SPI entsprechend der Tabelle mit dem Arduino zu verbinden. Bitte unbedingt prüfen, ob das eigene Display für 5V ausgelegt ist! Im Zweifel am 3,3V Pin anschließen und erst einmal damit versuchen. Die “Was ist das?”-Spalte in der Tabelle zeigt die ausgeschriebenen, gängigen oder alternativen Bezeichnungen der Anschlüsse; vielleicht hilft es dem einen oder anderen bei der Verkabelung. Ich fand diesen Beitrag von paulwb im Adafruit-Forum sehr hilfreich, um das Display nach einigen erfolglosen Versuchen endlich zum Laufen zu bringen.

Hier noch der Arduino-Sketch zur Darstellung der Animation wie im Video.