Tag Archives: adafruit

ИГГ1-64/64M Adventure

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It appends I spend a bit of time on eBay looking for uncommon or old displays such as the famous Nixie tubes. Large matrix displays emerge some time ago maybe due to the discover of an old stock. However, I never found someone using them, for a good reason. Around 360 Volts is needed to light up a pixel.

Gazotron

gazotronGazotron, or Газотрон is (or was) an Ukrainian electronic tube manufacturer (do not confuse with Gas-o-tron). It’s not easy to find information about this company, even gazotron.com is closed. But actually there is still plenty of their products available if you would like to buy electronic tubes, such as IN4-nixie tubes. The logo is dot inside a circle.

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They made in the 90’s different sort of dot matrix panels. They are quite large, 19x19cm, and for the moment I saw 3 kind of pixel composition. A 32×32 matrix, all pixels are green. A 64×64 matrix, pixels alternating green and red, and finally a 64×64 matrix with red-green-blue alternating pixels.

I bought one green-red some time ago, and recently saw a page on hackaday.io that revive my interest.

Seek for information

The short datasheet provided with the screens (shown in the mentioned page) explains the voltage values needed to light up the pixels as well as the timings, but it does not help to find a way to generate these high voltage signals.

My research on internet first leads me to this Youtube video demonstrating a 8×8 pixel drive, and a quick view of the breadboard circuit. Then I start to find forums written in Russian where someone manage to drive the all 32×32 matrix.

And finally, a piece of a datasheet showing a circuit example able to generate the ~400 Volts anode signal from a 200 Volts source.

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Test Drive

I reproduced the circuit on a breadboard as well, using a 180V ‘nixie’ power supply.

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Motivated by this success, I started Kicad and designed a PCB. I Selected SMT components in order to reduce the size of the 64 anode drivers and the 64 cathode drivers. The board arrived as perfect as usual with OSHPark.

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And they are working!

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Cabling and soldering

There is 92 components and 34 wires on each of the 8 boards to solder. As I don’t own a air soldering station, I did everything with a good iron and solid patience.

But it was worth the effort, they all work great.

Interface

I used the same micro-controller as the BIG_CLOCK to talk with the high voltage boards. Especially because it has at least the 32 outputs needed. To interface this controller with the outside world and being able to display some useful pictures, I used the serial port.

I could then make a tiny Java program that copy part of the computer screen and send it to the serial port.

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Fun with Pixel Dust

I was quite amazed by the code demonstrated on a 64×64 led matrix by Adafruit (https://www.adafruit.com/product/3649). So why not trying this on the IGG1 display?

I have a MPU-9250 IMU and a raspberry-pi zero. However I need to adapt the code for this accelerometer, and send the data to the screen with the serial port. I’m more comfortable with Java than C or python, then I translate the code from Adafruit in Java.

To conclude

The full story and details are on the hackaday.io page here:

https://hackaday.io/project/46302-1-64x64m-adventure

Sources and schematics are on the following github repository:

https://github.com/pierre-muth/IGG_-64x64M

It was really a good time see this screen getting back to life, now it needs a purpose such as a weather forecast display or a nice clock. A lot is possible with the raspberry pi, including the use of the PIR sensor to only turn on the screen when someone is around…

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PolaPi-Zero

8659491486300188651 The PolaPi camera flew to new adventures quite a long ago. I hope it still works and the new owner is using it time to time. I missed it a bit so it is time to rebuild one. In the meantime other parts got out on the market. Such as a smaller thermal printer and the smaller Raspberry pi Zero.

Here we have a good opportunity to try to slightly simplify the project and add features missing on the previous one.

By simplifying I mean avoid the thermal printer hack of the previous PolaPi, and use Python instead of Java. And by features I mean the possibility of review and re-print pictures. More details can be or will be on this Hackaday.io page.

Is all about monochrome.

The Adafruit nano printer is only capable of printing black dots. So it is for the Sharp Memory LCD. Except the printer’s resolution is slightly higher than the screen, I like the coherence between_mg_5911 what you see and what you get.

Vít Hašek made it’s own PolaPi and push the concept for his thesis. He called it the white box, in opposition of today’s black box devices.

It is mainly the reason why I made the new one white as well.

Under the hood.

The electronic hardware is similar of the previous one, except the screen.shematics01

However I used 3D printed part for the case.

A button is for taking picture and change to ‘live view’ mode. Another to print the picture file or change to ‘review’ mode. Two others to navigate through the image files. And finally a last one to initiate the raspberry pi shutdown

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The Python code and the way to get the LCD library compiled is still a bit messy at the time of writing, but I’ve put everything on github. Moreover, you can get the SDcard image on this dropbox.

Icebreaker Game

Abstract.

12026610_10207455771046540_1864584773_nAfter experimenting with the small receipt thermal printers and manage to make a portable camera, my brother came up with a very clever idea. He is organizer of a juggling convention, and he looked for a kind of funny game around beer selling and their receipt. The aim was to entertain and offer a beer every lets say 50 sold. He said we can do more than print pseudo randomly a winning ticket based on certain ratio.

The idea.

beerWe imagined a machine standing on a bar, with on the client side a camera pointing at you, a screen showing the camera output and few instructions. On the back side, a single button allowing the barman to launch the lottery for one ticket. What the machine do once you press the front big button (I really love these Adafruit massive buttons!), is taking a picture of you. And then there is two possibilities. If you loose, a souvenir receipt is printed with the picture of your face and a random funny quote. If you win, a winning receipt with the face of someone else is printed, and instructions telling you that if you find the random guy on the printed picture, you both won a free beer.

The printer.

2321The printer choice should consider reliability, speed and print
quality. Even if the last one is relative to what we can expect for black or white thermal printing. I moved from the affordable and small serial Adafruit 58mm printer to a more professional one. After some non conclusive test with a cheap 80mm Chinese printer, I finally get an Epson point of sale printer. The TM-T20 is USB and commands are very well documented on their website. If not set to the maximum print speed, they could make surprisingly good prints for bitmap pictures. It depends a bit of the paper quality as well. I get very nice results with BPA-free recycled paper roll.

The system.

Raspi_Colour_ROnce again, the raspberry pi is a nice card and of course perfectly capable of doing such a process. There is the official camera module, even if a basic webcam would make it as well, USB ports for the printer, HDMI for a screen, GPIO for buttons and leds. But most importantly, I can reuse a lot of code form the Polapi.

The software is written in Java and uses two external libraries. One for GPIO – Pi4J and an other one for USB – usb4JavaIn addition, the native raspbian program raspividyuv is used to get the camera frames. The camera output is on top of everything and always visible on the screen. The all Java software part is hosted on github. The runnable Jar file must be launch on the Raspbian LXDE environment and could be easily auto-launched. There is some logs here, but I must complete them a bit.

The case.

In the view to avoid yet another device taking dust in the garage, I made the case looks like an arcade. I just have to exchange the front panel to have a raspberry pi Mame machine ! (That will instead probably take the dust of the attic, but with style, surrounded by retro consoles)

Wood sawing 

Case filling

Resulting device

Outlook.

It was quite a success on the Juggling convention, it brought fun and few free beers ! It ran smoothly without any reboot despite I expected some bugs.

After being used on a week-end for around 500 prints, it will be used on a Hackathon in Geneva with a slightly different mode.

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Instant-Printing-Point-and-Shoot camera

polapi01Here another project finally finished ! The Bluetooth thermal printer was fun. Unfortunately I didn’t get it work with apple i-stuff. A stand alone camera, as the Polaroid is in fact even more fun !
I used brass angle rods, glass fiber plates and screws for the case. A raspberry pi 2, this time with its own camera module. A TFT screen, the thermal printer, and a lipo battery. More details here:

hackaday.io/project/7176-polapi

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During a party, the 3.6Ah lipo was able to keep running the raspberry pi for around 6h, plus around 100 prints !
I found a large aperture CCTV lens to get maximum sensibility. The counter part is it need to be manually focused.

It is worth to mention few facts about the paper. Thermal paper is very cheap and could be easily found without BPA, but it is sensible to sunlight and heat. Exposed to sun, the prints will fade with time.

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