raspberry pi

1660 Articles

It’s An Upright Piano, It’s A Looper, It’s A Pi Project

September 6, 2015 by 6 Comments

We don’t really get out much, but we have noticed that there are brightly painted upright pianos in public places these days. Research indicates that these pianos are being placed by small, independent local organizations, most of which aim to spread the joy of music and encourage a sense of community.

[Sean and Mike] took this idea a couple of steps further with Quaver, their analog looping piano. Both of them are maker/musicians based in Lancaster, Pennsylvania, which happens to be a hot spot for public pianos. [Sean and Mike] often stop to play them and wanted a good way to capture their impromptu masterpieces. Quaver is an antique upright that has been modified to record, save, loop, and upload music to the internet. It does all of this through a simple and intuitive user interface and a Raspi 2. Quaver works a lot like a 4-track recorder, so up to four people can potentially contribute to a song.

The player sits down, cracks their knuckles, and presses our personal favorite part of the interface: the giant, irresistible record button. A friendly scrolling LED matrix display tells them to start playing. Once they are satisfied, they press the button again to stop the recording, and the notes they played immediately play back in a loop through a pair of salvaged Bose speakers from the 1980s. This is just the beginning of the fun as you play along with your looping recording, building up several voices worth of song!

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Orange Is The New ($15) Pi

September 5, 2015 by 105 Comments

When the Raspberry Pi came on the scene it was hard to imagine that you could get a fairly complete Linux system for such a low price. The Pi has gotten bigger, of course, but there are still a few things you miss when you try to put one into a project. Wifi, comes to mind, for example. The first thing you usually do is plug a Wifi dongle in, consuming one of the two USB ports.

The Orange Pi is a direct competitor and has a few variants. Originally, the board cost about $30 but sports WiFi, a 1.6 GHz processor, 8 GB of flash, and a SATA interface. There’s now a reduced version of the board for about $15 that deletes the flash and SATA along with the WiFi and one of the original’s 4 USB ports. Still, the Raspberry Pi doesn’t have built-in flash. And the $15 Orange Pi PC has the things you’d expect on a Pi (HDMI and Ethernet) along with other extras like an IR receiver and an on-board microphone. Not bad for $15 considering it has a quad-core processor, a GPU and 1GB of RAM. Continue reading “Orange Is The New ($15) Pi” →

RaspiDrums Uses Expensive Sensors

September 4, 2015 by 3 Comments

Piezoelectric sensors are great for monitoring mechanical impacts with a microcontroller. Whether you’re monitoring knocks on a door or watching a heartbeat, they are a cheap way to get the job done. They do have their downsides, though, so when [Jeremy] wanted to build an electronic drum set, he decided to use more expensive accelerometers to measure the percussive impacts instead.

Even though piezo sensors are cheap, they require a lot of work to get them working properly. The ADXL377 3-axis accelerometer that [Jeremy] found requires much less work, plus provides more reliable data due to a 1kHz low-pass filter at the output. In his setup, a Raspberry Pi handles all of the heavy lifting. An ADC on each drum sends data about each impact of the drum, and the Raspberry Pi outputs sound via the native Alsa driver and a USB sound card.

This project goes a long way to show how much simpler a project like this is once you find the right hardware for the job. [Jeremy]’s new electronic drums are very well documented as well if you are curious about using accelerometers on your newest project rather than piezo sensors. And, if you’re into drums be sure to see how you can have drums anywhere, or how you can build your own logic drums.

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Building A Better Mousetrap With The Raspberry Pi

August 31, 2015 by 25 Comments

Build a better mousetrap, and the world will beat a path to your door, but what about a smarter mousetrap? [Alain] decided to find out by making a Raspberry Pi-powered, Internet-connected smart trap. The brains of the operation is a Pi running Arch Linux. Connected to that is a IR trigger, a servo to unlatch the sliding door, and a camera to see your new friend.

The housing of the trap is CNC cut foam PVC board, which is both easy to cut and to clean. Once the IR beam is broken the Pi turns the servo, which pulls a pin on the front door. Once your new friend is settled in a LED light turns on to illuminate the subject, a picture is taken and sent via email.

With automated alerts you don’t have to manually check the trap, and you also don’t have to worry about a trapped animal being inside for too long. Join us after the break for a demonstration video showing off all the features, and a real world example.

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Voice Command With No Echo

August 30, 2015 by 7 Comments

[Naran] was intrigued with the Amazon Echo’s ability to control home electronics, but decided to roll his own. By using a Raspberry Pi with the beta Prota OS, he managed to control some Phillips Hue bulbs and a homebrew smart outlet.

Prota has a speech application, which made the job simpler. He does point out though, that his project doesn’t replace the Echo’s ability to answer questions by searching the Internet. The advantage, though, is it is easily tailored to your specific application. Also, if you have a Raspberry Pi hanging around, you can’t beat the price. Continue reading “Voice Command With No Echo” →

Two-Axis Solar Tracker

August 25, 2015 by 32 Comments

Solar panels are an amazing piece of engineering, but without exactly the right conditions they can be pretty fickle. One of the most important conditions is that the panel be pointed at the sun, and precise aiming of the panel can be done with a solar tracker. Solar trackers can improve the energy harvesting ability of a solar panel by a substantial margin, and now [Jay] has a two-axis tracker that is also portable.

The core of the project is a Raspberry Pi, chosen after [Jay] found that an Arduino didn’t have enough memory for all of the functionality that he wanted. The Pi and the motor control electronics were stuffed into a Pelican case for weatherproofing. The actual solar tracking is done entirely in software, only requiring a latitude and longitude in order to know where the sun is. This is much easier (and cheaper) than relying on GPS or an optical system for information about the location of the sun.

Be sure to check out the video below of the solar tracker in action. Even without the panel (or the sun, for that matter) the tracker is able to precisely locate the panel for maximum energy efficiency. And, if you’d like to get even MORE power from your solar panel, you should check out a maximum power point tracking system as well.

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Raspberry Pi Halt And Catch… Well, Halt

August 25, 2015 by 38 Comments

As far back as we can remember, there have always been hacks, exploits, and just curiosity about undocumented CPU instructions. The Z80 had them. Even the HP41C calculator had some undocumented codes. The HCF (Halt and Catch Fire) instruction was apocryphal, but we always heard the old video controller chips could be coaxed into blowing up certain monitors. You don’t hear too much about things like that lately, perhaps because fewer people are working in assembly language.

[Sergi Àlvarez i Capilla] not only works in assembly language, he was writing an ARM assembler when he noticed something funny. Instructions are built in a regular pattern and some of the patterns were missing. What to do? [Sergi] lost no time trying them out.

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