Tinkering with Raspberry (and other things)


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


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.


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


LED marquee – Teardown

Recently I saw an outdated (I thought) LED marquee sign in a thrift store. As these things make great tinkering objects I went inside and took a closer look. The sign looked fine and (tinkerer’s heaven) did have a serial port. Complete with RS232-to-USB adapter, remote control and power supply.

I did a quick research and decided to buy that thing. The technical data I found on the Internet were talking about up to 26 “pages” of text with 420 characters each, multiple effects and so on. Simply a must have…


The most interesting thing was, of course, the serial port. The idea is to have multiple RSS feeds on display. The news, the weather and so on. Everything controlled from a Raspberry Pi.

To understand how I can interface with the sign I will (of course) open it and take look at the insides. I thought I make this a blog entry to let you participate in my findings and (hopefully) show you something about “reverse engineering” electronic devices.
Continue reading

Edit Source Code Remotely

Recently I caught myself juggling with 5 open terminal sessions simultaneously. Four windows were showing different source files from a project I am working on and the fifth terminal was the commandline from where I started compilation and ran the programs. This was really annoying because even on my 27″ monitor the terminal windows took all the space and I frequently had to change desktops and so on.

So the question arose: “Can’t this be done in a more efficent way?” Continue reading

Resources on GitHub

After being quiet for a while I finally managed to finish some documentation on the All-Out-Board. I also decided to put the complete works into the public domain under the GPL V3 license. So if you like soldering and tinkering, feel free to use it. Either as a start for new projects or personal education.

The following sources can be found on my All-Out-Board Repository on GitHub:

  • Eagle files for schematic and board
  • short assmebly and testing guidelines
  • associated sourcecode from the posts in this blog

I hope you will have fun. As this blog continues I will start adding a “blog” repository where you can find all the scripts I am going to mention in my posts.

A permanent link to the GitHub repository is added on the right side of this blog.