MyRaspberryAndMe

Tinkering with Raspberry (and other things)


Nerf Barrel Extension + AmmoCounter + Chrono

OK, so now I am into Nerf-Guns. Seems my 8-year old alter ego has taken over. But, following the motto from the legendary eevblog, don’t turn it on, take it apart!

These Nerf blasters come with different technologies. There are purely mechanical ones, powered by springs and compressed air, and then there are some that use motors and flywheels to accelerate the funny foam darts. My first Nerf was a “Recon MK II”, mechanical. As soon as I held it in my hands I wanted to add an ammo counter (Remember: I am old and the Alien movies, especially the M41A pulse rifle, are part of my life…).
The question is how to add something electrical to a purely mechanical thingie. And I had some constraints: it has to be reversible and it needs to remain child-safe for the occasional battle with kids. So the voltage/motor/whatever modifications found on the internet were a no-go.
Well, the removable barrel extension seemed to offer enough space to integrate some circuitry… Continue reading


Tiny Word Clock with Attiny85

The “Hello World” of microcontroller projects undoubtedly is a clock. As this was my first try with an Attiny85 I decided to build a tiny version of my big living room word clock (which is 40 x 40 cm) and put it into an IKEA picture frame.
I have been using an 8×8 LED-matrix (WS218b, Adafruit Neopixel compatible) and the first challenge was to get the German words for the different times into this 64 positions. The source code is heavily based on Adafruits tutorials. Continue reading


Elevator Information Display using two ILI9341 TFTs

It has been a long time since my last post, well, I have been busy and had significantly less time for tinkering.

But back again. Take an old elevator panel, two displays and a Raspberry Pi and transform it into a home information system.

Ingredients and Original Idea

  • A really old but massive elevator panel with all the original wiring, the buttons and even the led-matrix displays.
  • A Raspberry Pi (of course)
  • Two ILI9341 2.2″ TFT panels
  • Adafruit’s python library for ILI9341

My original idea was to reuse the LED-matrix from the old panels to display some information. This unfortunately was not possible as these are not ‘normal’ matrix displays but do have some sort of logic built in. Applying a voltage on the terminals (in the middle of the picture) does display the preprogrammed floor numbers in the display. Well, this is not a big issue, TFT displays are much cooler.
Here is an image of the unaltered elevator panel:original elevator panel

Continue reading


Quicktip: Selfmade LED lamp with T5.5 socket (Telephone Lamp)

For my newest project, the “intelligent desk clock” (I shortly mentioned it at the end of the last post) I need to have big momentary switches that could be illuminated. The idea is to let the switch blink if there is user interaction needed.

I found some switches that need old-style bulbs with “telephone lamp” socket, technically a “T5.5” or “T5.5k” socket. These are usually bulbs running at 12V or higher. I want to realize the project with an Arduino or a Raspberry Pi, so 5V is the voltage I have available. LED lamps with T5.5 socket are rather expensive, luckily I was able to order 10 pieces for 7 EUR from ebay. They do have red LEDs but I thought I could desolder them and solder some white ones to the socket.

Today I found some cool switches at my electronics shop, immediately purchased a bunch and at home, was able to completely disassemble the switch. So I now am able to put some label behind the orange button! Of course the shop had the fitting bulbs in stock, with real lamps rated at 12V, but for 0.5EUR a piece. So I took some, too.

Here are pictures of the switch and the disassembled parts:

P1010441

Make your own T5.5 LED lamp

Take a look at the T5.5 lamp from the shop. It’s just a metal socket an the bulb soldered to it. The metal parts are glued to the bulb with tiny spots of some hot glue. With the help of a scalpel and some brave cutting and bending (watch your fingers if the glass breaks) the bulb can be detached from the metal socket. With a firm pull the whole bulb can be teared off. Now take a soldering iron and clean the soldering spots and, using the scalpel, clean the glue residue from the socket.

Shorten the wires on the LED (remember which side is Anode and Cathode, respectively) and the resistor (I used 220 Ohms, the usual value when using 5V and an LED). Solder the resistor to one wire on the LED and bend the wires slightly outward so they will make contact with the metal socket when fitted in. (One square of the paper is 5mm x 5mm)

P1010437

Now fit the LED into the socket so that the socket is just around the bottom of the LED. You will need some sort of fixation tool like alligator clamps to make your life easier. Now cautiously solder the wires to the socket and you’re done. You should end up with something like this:

P1010440

You will definitely need all your patience making this LED thingy. Taken into account that an LED lamp with T5.5 socket will cost around 5EUR (6 USD) each, it’s worth the effort.


Pi-Hicle final – motor-control and autonomous driving

So this is going to be the final part of the “Pi-Hicle” series (here are Part 1, Part 2, Part 3, Part 4). There is some good news and some bad news… But first a video of the vehicle moving:

The good news is that the BigTrak is in fact runnning on its own, avoiding obstacles with its three IR sensors. The bad news is that I have discarded the Raspberry Pi for this project. The vehicle is controlled by an Arduino mini now and there won’t be a Raspberry Pi in it in the near future. Now why this?

  1. I fell in love with the BigTrak and I simply can’t make any more holes in it, let alone ripping the keyboard off
  2. My plan to decrease the speed gradually as obstacles are detected does not work. There is not enough torque to move the wheels when the speed goes below 60% (and that is still too fast indoors, at least at my home)
  3. With the vehicle moving that fast a video camera is obsolete, one wouldn’t get a clear picture of anything (and I don’t have pets to annoy…)

So I am going to share the last steps in making this project. This involves mounting the sensors and putting everything together and the simple, yet working, code for making the BigTrak drive. Continue reading


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Pi-Hicle part 3 – Big Trak autopsy and findings

This part is about the internals of the 2010 model “Big Trak”. I intend to use this toy as a base for my raspberry Pi powered vehicle. In part 1 of this series I covered the basic idea of my “Pi-Hicle” and recreated the Big Trak logic in Python. Part 2 was about displaying the programmed path on a display. Now I am lucky, because the “best girlfriend ever” gave me a real 2010 Big Trak for christmas. She even made a label, reading “Present for disassembly”. So I am doing nothing wrong here…

There are numerous resources out there about disassembling the Big Trak models, so I won’t cover this. Locate the screws and pay attention for those hidden under the grey rear bumper, then lift the top carefully and continue. David Cook from “The Robotroom” (www.robotroom.com) has extensive material about the original 198x Big Trak. For the new series of Big Traks you can find modding instructions with lots of pictures at srimech’s blog and some analysis of the circuits at the “Singleton Miller Wiki“. I am going to concentrate on my additional findings in this blog post. Nevertheless, here’s a quick overview where the screws are located. Blue arrows are “visible” screws, the red arrows point to where the additional screws are hidden under the bumper thingie:

chassis_bot

Continue reading


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Pi-Hicle part 2 – Programming Movement And Display Path On Screen

In part one everything was about getting that legacy touch screen to work. Now it’s time to re-live my childhood. I am going to include the logic that will move my Pi-Hicle around.

In case you didn’t read the first part, here’s a short video demonstrating the GUI and screen output. The path can be programmed and will be displayed on screen with triangles showing the Pi-Hicle’s heading.

orientationThe original Big Trak was able to hold 16 instructions in its memory. Sixteen! With the Raspberry Pi as a brain this number is significantly higher, although not really needed. The programming was done with a touch pad where one could select the direction (forward, back, left, right), wait and fire. Every command was followed by one or two digits, telling the vehicle how many units of its own length to move. The numbers after the “left” and “right” instructions were used to program a turn if xx degrees. To make things easy for us children, the angle to move was scaled according to an analogue clock. 15 meant 90 degrees, 30 was 180 etc.

From the image it is clear that “Right-45” would have exactly the same effect as “Left-15”, although the vehicle would be rotating in the opposite direction. Continue reading


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New Project: The “Pi-Hicle” – What is is about

Well, sooner or later it had to be. I am going to build a vehicle that is controlled from my Raspberry Pi. I know, there are tons of such projects out there, but this simply is a must. And I think I am doing things a little different…

This blog post is meant as a short “introduction” on why and what. The actual documentation of my efforts will go in blog posts with a “Pi-Hicle Part xx – some description” title.

bigtrakThe idea started the instant I saw a “Big Trak” toy vehicle in a shop. Back in around 1980-1982, I can’t remember exactly the year, this was the toy of dreams. I wanted one for christmas but then I met a new boy at school who was deeply in electronics (we were about 13-14 years old and he was repairing TVs and even built an 30-channel analogue mixer!). His bigger brother had an ZX-81 and we spent every afternoon programming that thing. So I opted for my own ZX-81 for christmas, the “Big Trak” was history.
Fast forward more than 30 years: The “Big Trak” is back in shops. I am still tinkering with electronics and, even better, I can buy my own christmas presents… Hooray!

So the plan is this: take a Raspberry Pi to control a vehicle. The keypad on the “Big Trak” will be exchanged for a touch-screen. The actual driving – and later environmental sensing – will be done by an Arduino. This way if I do something wrong, it’s just a new Arduino for 10 bucks, not a 40 bucks Raspberry Pi.

Continue reading


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AM03127 LED marquee + Arduino + Bluetooth = RaspberryPi remote control

After some days of soldering, testing and coding I am now able to control my LED marquee remotely via bluetooth from my Raspberry Pi. Using an Arduino Pro Mini (5V model) and the HC-05 module mentioned in my last blog post, I was able to mount all components inside the sign’s housing.

Some features of the bluetooth enabled display:

  • send messages to display (up to two messages with a length of 360 characters each are possible)
  • select display mode (message – time – off)
  • set time from and to Real Time Clock
  • set display intervals
  • increase/decrease speed of marquee

The sourcecode consists of the Arduino sketch to control the sign and a Python class that encapsulates the communication and message handling to the LED sign. As always, the sources will be available in my GitHub repository (direct link to sources). In this post I will describe the hardware and software developed to accomplish this. Some soldering skills may be required… Continue reading


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Bluetooth Serial Communication with HC-05

Adding bluetooth support for a mouse or keyboard is easy with the Raspberry Pi. Things go a different route as soon as you’re trying to communicate with other electronic gadgets. There are numerous howtos and instructables out there that do serial communication via bluetooth. But all of them (at least those I have read) use bluetooth modules connected to the serial port of the Raspberry Pi. I had a similar solution at first, but then I accidentally connected one of my bluetooth modules the wrong way and fried it…  Here’s a picture of it. Before frying it, I added a sticker (“S” for Slave) that is now burned, too.

hc05-fried

In the lower right is the voltage regulator that literally exploded. However, these specific modules are cool for tinkering, as they allow TTL (5V) levels!

The HC-05 modules are very clever pieces of hardware, as they translate incoming bluetooth communication to serial data. So once configured this gives the tinkerer the possibility to achieve serial communication over bluetooth. The HC-05 acts transparently, meaning that you just communicate with the serial port it is connected to and the module then sends/receives via bluetooth.

To be able to continue tinkering with communications I gave the “Bluetooth USB Dongle” with Raspberry Pi alternative a second chance. Weeks ago I have not been able to get bluetooth running using a serial communication protocol. In fact, I was not even able to pair any of my computers and the Raspberry Pi.

My plan is to modify my LED sign to wireless communications. As a proof-of-concept I am going to use my Raspberry Pi – with attached bluetooth USB dongle – to communicate with a HC-05 bluetooth module connected to an Arduino.

To quote from “The Big Bang Theory”: “Everything is better with bluetooth!” Continue reading