Minimalist User Interface For Headless Raspberry Pi Applications

March 13, 2013 by Mike Szczys 8 Comments

minimial-ui-for-headless-rpi

[Jason Birch] just finished building a beautifully simple user interface for the Raspberry Pi. The goal was to keep it small and intuitive while still providing a range of functionality. His add-on hardware gives feedback using several LEDs and a four-line character LCD screen. It provides control using just four momentary press switches.

The base for the add-on hardware is a chunk of protoboard the same size as the Pi itself. This is just slightly wider than the LCD screen, leaving room along the top for the row of buttons with different colors of LEDs in between them. Look closely in that nest of point-to-point wiring and you’ll find the dual pin-socket which mates with the RPi GPIO header. One important note from [Jason] mentions that the LCD screen R/W pin must be tied to ground. This keeps it from going into read mode, which would push 5V over the I/O pins, potentially damaging the 3.3V tolerant header on the RPi.

Throw in a battery and that pretty much covers the hardware. To see how he’s using it you’ll want to view the video clip after the break.

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Wiimote Controlled RPi Robot

March 7, 2013 by Eric Evenchick 24 Comments

[Brian] has brought together a powerful collection of hardware to build a robot. The end goal is to have a robot that’s controlled by a Wiimote.

The Wiimote communicates over Bluetooth with a Raspberry Pi, which is running a Python script. This script uses the CWiid Python module to communicate with the controller, and [Brian] has detailed instructions on getting the Wiimote working with a RPi. The RPi controls an ATmega based development board over SPI, which drives an h-bridge to control the two DC motors that move the robot.

[Brian]’s code for this could be helpful for anyone looking to control their RPi with a Wiimote. Since Wiimotes and Bluetooth dongles are fairly cheap nowadays, this is a great way to drop in wireless control to any RPi project, or even to control your media center from the couch.

After the break, check out a video of the build in action

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Dynamic Bicycle Headlight Uses The Open Road As A Display

March 6, 2013 by Mike Szczys 33 Comments

This thing is so cool it almost looks fake. But [Matt Richardson] isn’t a hoaxster. He actually built what might be called a heads-down display for your bicycle. He refers to it as a headlight because it borrows a similar function. It mounts on the handlebars and shoots light off the front of the bike. But it’s more than just a battery and a bulb, this uses a pico-projector to give that light some meaning. In the video after the break he shows it off on the streets of NYC.

So far he’s only displaying information that has to do with the speed of travel, but the proof is there just waiting for a brilliant new use. Feeding the projector is a Raspberry Pi board. For this prototype [Matt] mounted it, along with the portable cellphone charger which plays the role of the power source, on a hunk of hardboard strapped inside the bike frame.

If you’re thinking of doing this one yourself beware of the BOM price tag. That projector he’s using runs upwards of $400. We wonder if you could hack together a rudimentary replacement with an old cellphone screen and this diy film projector?

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Audiobook Player Used Only NFC Tags For Control

March 4, 2013 by Mike Szczys 14 Comments

[Martynas Mickevičius] has a Grandmother who is visually impaired. She enjoys listening to audiobooks and has been doing so using a DVD player for quite some time. The problem is that there is no way for her to save her position in between listening session. He set out to help by building a dedicated audiobook reader that doesn’t have any buttons.

The project was inspired by a one-button reader we featured back in November. Like that project, [Martynas] chose to use the inexpensive, yet powerful Raspberry Pi. The main difference comes in the control method. He’s using an NFC tag reader, which is mounted in the top portion of the RPi case. The image above shows the rig during prototyping, but his final version is all bundled up in the pink enclosure and only needs the power and audio cables connected to it. See for yourself in the demo after the jump.

Each book has its own NFC tag. When she’s done reading she can simply cut the power and it will resume in the same place the next time it is plugged in. The tag setup is a vast improvement since it allows an entire library to be stored on the SD card and chosen using a different tag. With this hardware in place it should be trivial to code extensions to the system, like a script that uses text-to-speech to announce which book is being played before playback starts.

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Using OpenCV With The Raspberry Pi

March 4, 2013 by Brian Benchoff 47 Comments

When we first heard of the Raspberry Pi we were elated that projects that once required a full-blown computer could now be done on a tiny, and cheap board running Linux. Unfortunately, we haven’t seen much in the way of using computer vision algorithms on the Raspi, but thanks to [Lentin] the world of OpenCV is now accessable to Raspberry Pi users everywhere.

[Lentin] didn’t feel like installing OpenCV from its source, a process that takes the better part of a day. Instead, he installed it using the synaptic package manager. After connecting a webcam, [Lentin] ssh’d into his Raspi and installed a face detection example script that comes with OpenCV.

It should be noted that [Lentin]’s install of OpenCV isn’t exactly fast, but for a lot of projects being able to update a face tracker five times a second is more than enough. Once the Raspberry Pi camera module is released the speed of face detection on a Raspi should increase dramatically, though, leading to even more useful computer vision builds with the Raspberry Pi.

Building A Touchscreen XBMC Setup With The Raspberry Pi

March 2, 2013 by Mike Szczys 29 Comments

[Andrei Istodorescu] has been hard at work building a 7″ touch-screen rig which runs XBMC. It may be upside-down, but the Raspberry Pi board which is front and center is still easily recognizable. There’s a lot of stuff connected to it in order to pull this off, and even more software configuration. But as you can see in the clip after the break he did get it working!

The screen is an eGalaxy 7″ touch sensitive module he picked up on eBay. It sounds like it was meant for a backup camera in the dashboard of a car. He compiled his own Linux kernel to add support for the screen. It uses HDMI for the video interface with the driver board, and the touchscreen connects to one of the USB ports. The rest of the setup involves compiling XBMC with touchscreen support and calibrating the screen to accurately sense input.

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Optical Data Transfer Project At Local School’s Family Science Night

February 28, 2013 by Mike Szczys 9 Comments

optical-data-at-family-science-night

[Dave] wanted to show off a project at his 4th-grade son’s school during their family science night. We haven’t heard of an event like this before but it sounds like a fabulous idea! He had a new laser he wanted to include in the project, and noticed that his son was learning about how ASCII maps letters to binary number when the idea struck. He ended up building an optical data transfer system that demonstrates binary code.

This presents a fantastic learning opportunity as the project invited the school kids to select encoded strips like the ones seen above to form a secret message. The laser is pointed at a photosensor which is being read by a Raspberry Pi board. The Python code looks for a baseline and then records increases and decreases in intensity. Since the translucent tokens have either holes or black lines for 0 and 1 the baseline approach does away with the need to clock in the data. [Dave] reports that everyone who tried out the experiment was fully engaged at the prospect of pushing pieces of tape through the sensor and watching their secret message appear on a monitor.

He was motivated to write about this project after reading about data transfer using an LCD screen and photosensor.