The circuit as it ran for two years

The circuit as it ran for two years

Normally, it would make much more sense to publish a project when it is done. In this case, I was sure that I had done exactly that. It’s just a few days since I realized that I didn’t. Funny, it’s been exactly three days before I replaced the project by something else. However, even if it’s a bit late, I’ll deliver…

In early 2014, we renovated our living room. One wall got a rocky structure, and I thought that was the perfect place for a grazing light from above. This screamed for LED-strips. Fooling around with my daughters, I mentioned a plan of installing a pink light. The plan was to go with warm-white, but they insisted on a pink light… two against one, I was in defense position. :-)

Theoretically, a simple RGB-strip can be made to give white light. Practically, most times that’s a really ugly tone of white. So I installed a warm-white strip next to the RGB one. The controller that was delivered with the RGB-strip wasn’t able to power this combination, so I needed a RGBW controller. I couldn’t find an affordable one, so I had to build it myself.

That's how it works

That’s how it works

If I remember correctly, that was my first Arduino project. And it was surprisingly easy to do. I built a first prototype with an Arduino Uno, and with the great infrared receiver library by Ken Shirriff I was able to control a RGB and a white LED after just two hours. Using my trusty Logitech Harmony, which also controls the rest of my media system.

The second prototype I built using MOSFETs, to test how I would be able to control the LED-strips with an Arduino. They are powered with 12V, after all.

The final build is pictured on the photo above: an Arduino Pro Mini (the one without USB interface), and a simple PCB that is wired for controlling the strips. There’s an infrared receiver wired to the Arduino. Initially, that was a TSOP31238, but I fried it just before finishing the project by wiring it wrong. Wanting to get this done, I gutted an old DVD player. I don’t have the slightest idea what type of receiver this is, but it works. :-D

That means: it did work. Almost exactly for two years. Till today. Now it’s obsolete — as I said. Sources and documentation go by the name of IRlicht, I published today.

Oh, and if that’s of anybodys concern: until today, the lamp was used almost only in the white mode. The colors — and especially the color changing modes — were used only for testing and for showing how it works. It was used rarely enough that I had to look up the used keys in the source code…

Most pins are in use

Most pins are in use

The ESP8266 is an interesting chip, I mentioned it here several times (sorry: mostly german). In a short description, it’s a freely programmable microcontroller. Compared to Arduino & Co., it’s a real number cruncher. The ESP is faster, has more memory, and the best thing: it has builtin WiFi. You’ll find more information all over the network, a basic overview is contained in Wikipedia.

I tested several boards when playing with this chip. Today, I want to describe one that goes with the name Witty Cloud.

Basically, it’s a board with an ESP-12-F, a USB connector that delivers power, a little pushbutton, a LDR (Photoresistor) and a RGB-LED. So there’s plenty of hardware to play with. When you buy the module, you receive a stack of two PCBs. The lower one has a second USB connector, which is equipped with a serial converter. So it’s not only used as a power source, but also as a programming and debugging interface. Furthermore, there’s a reset- and a flash-button on the lower board. After programming, you just need the upper board, and you can even send newer firmware versions to it over the air (OTA).

The  lower board is only used for programming

The lower board is only used for programming

Stacked like this, the module costs less than three Euro, you just need a USB cord and a compiler to start programming. I suggest using the Arduino IDE, it’s very easy to use, even for beginners. After installation of the ESP8266 extensions, it’s best to select WeMos D1-Mini in the board manager, this way everything works fine.

Unfortunately, it’s not easy to find proper documentation for the Witty. So i scribbled the picture above, at first to have some kind of reminder for myself. So the pin labeled GPIO13 is connected to the blue channel of the RGB-LED, in the Arduino environment it’s called D7.

Label Pin (Arduino) Purpose
REST Reset
ADC A0 Analog input, connected to LDR
CH_PD Chip Power-Down
GPIO16 D0 GPIO, freely usable
GPIO14 D5 GPIO, freely usable
GPIO12 D6 GPIO, green channel of RGB-LED
GPIO13 D7 GPIO, blue channel of RGB-LED
VCC +5V power
TXD TX Serial interface
RXD RX Serial interface
GPIO5 D1 GPIO, freely usable
GPIO4 D2 GPIO, connected to pushbutton
GPIO0 D3 GPIO, connected to flash-button, not really freely usable
GPIO2 D4 GPIO, connected to blue LED on the ESP-Module
GPIO15 D8 GPIO, red channel of RGB-LED
GND Ground

I would be highly interested in a circuit of the board, and if you have any corrections or suggestions: just let me know.

Mein Fazit: ein echt interessantes Board. Wer mehr GPIO braucht sucht vielleicht lieber nach einem NodeMCU, wer sowieso einen LDR oder eine RGB-LED braucht sollte zugreifen. Ich habe mittlerweile einige davon hier, und eine Firmware mit der ich die Dinger hier im Haus verteilen möchte ist auch fast fertig.

Oh, das Bild habe ich übrigens mit einer Grafik aus diesem Projekt gemacht, das ist die Witty Cloud für Fritzing.

I mentioned this project in an article (german only) on this blog, it dates back from November 2012. Somehow I never showed it, I don’t really know why.

Those who read this blog for a while know that I have a deep faible for computer keyboards. You don’t get the full picture from my english language articles, but in german you can find many keyboard related articles on this site.

Amongst others, my collection contains two vintage Apple keyboards. There’s a — really not too shabby — Apple Extended Keyboard II, which was built between 1990 and 1994. Many enthusiasts claim that this is the best keyboard ever produced by Apple, partly of course because of it’s mechanical nature with the Alps switches.

Even more original — and in my eyes it’s a typical Apple product — is the Apple Adjustable Keyboard, 1993 vintage. Typical Apple? As I said, in my eyes: it was expensive for its time, and above all the visual appearance of the product is more important than functionality. Even though there are arrow-keys on the main keyboard, I personally wouldn’t want to miss function- and navigation-keys (Home, End, PgUp, PgDown). And if you connect the additional keypad, you really have to have long arms to reach your mouse… :-/

However, I wanted to give both a try. And since I don’t have access to a computer with ADB interface — Apple killed it in 1999 — I needed a converter. You can buy this stuff, but you don’t have to.

On geekhack.org, there’s a japanese developer called hasu, who is tmk on Github. He created and published the TMK Keyboard Firmware Collection. That’s a firmware that can be run on several AVR-based platforms, notably the Teensy 2.0 which is well known in keyboard communities. The firmware is able to ‘talk’ several different keyboard protocols. Of course, USB in one direction, to be connected to any modern computer. In the other direction there are protocols like PS/2, Sun or Apple Desktop Bus. The custom firmware is loaded with features even expensive modern high end boards fail to deliver. It’s possible to program macros, use media keys or control the mouse pointer with the keyboard.

Unfortunately, I didn’t have a Teensy at home. But I had all the parts to build something compatible, and all the tools to etch a fitting PCB. So I fired up KiCad and designed a minimal circuit, from that it wasn’t too difficult to create a PCB layout:

(The KiCad files need a bit of a workover, so I won’t publish them here. But it should be easy to recreate the circuit following the two screenshots.)

ADB USB Converter

ADB USB Converter

The finished converter measures in at 2x5cm, that’s really tiny. But the important thing is: it works!

I could probably use the ADB mouse with an off-the-shelf converter. But honestly: even a hardcore fanboy would prefer a modern pointing device without the ball in it. That is: a while ago I had the opportunity to play a bit with System 7.5 (the Apple operating system from the same era as the two keyboards), and I have to confess that the Adjustable Keyboard did its part for the authentic user experience… :-D