Japanese Drumming Sensei


If you’re looking to learn the art of playing Japanese drums, or Taiko, this hack, done as a school project by [Cornell] students, could be a really helpful aid. The project write-up is very impressive and includes a detailed explanation of their work, the source code, and a bill of materials if you’d like to try to duplicate this device.

The tutor device is able to tell between soft hits, hard hits, and rimshots using a piezoelectric sensor hooked up to an ATmega1284P microcontroller. This data can then be transmitted to the “follower” drum using an infrared transmitter. These beats can be used in several modes including: follow the leader, metronome, repeat after me, and drum battle mode.

Ok, maybe there’s no drum battle mode, but be sure to check out the demonstration of the Taiko teaching aid after the break.  There’s a lot of details about the build, but they start some calibration drumming around 4:00 if you’d just like to see it in action. [Read more...]

ATmega1284 as an 8-voice 32 kHz synthesizer

A couple of things strike us about this 8-voice 32 kHz synthesizer. First is the cleanliness of the prototype. As you can see, each part has plenty of room on its own board and all are interconnected by 10-pin IDC ribbon connectors. But you’ll have to see the video after the break to enjoy the impressive sound that this puts out. You’ll hear it play the Super Mario Bros. theme; it does it with passion!

To get audio from the digital microcontroller [Mike] built his own R2R digital to analog converter. The resistor ladder is built from sixteen resistors, which feed a rail-to-rail amplifier. The sound is mono but the playback is polyphonic thanks to the work done by the ATmega1284. It is reading MIDI commands coming in from an external controller (we assume it’s the computer on which the hardware is sitting). The chip’s 128 KB of Flash memory leave plenty of room to store samples, which are selected from a lookup table based on the MIDI data. If more than one sample is to be played the chip averages the data and sets the 8-bit output port accordingly.

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Building the worst Linux PC ever

Linux is generally considered the go-to OS for under powered computers. Wanting to challenge the preconceived notion that Linux requires ‘a computer made in the last 20 years,’ [Dmitry] built the worst Linux PC ever around a simple 8-bit microcontroller.

The ATMega1284p [Dmitry] used doesn’t have a lot to offer as far as RAM and storage goes; just 16 kilobytes of SRAM and a paltry 128 kilobytes of Flash storage. While this may be voluminous in the embedded world, it’s peanuts compared to the gigabytes of RAM and hard drive space on even a low-end netbook. To solve this problem, [Dmitry] threw an antique 30-pin RAM SIMM at the problem. It’s wired up directly to the microcontroller, as is the 1 Gigabyte SD card that serves as the PC’s hard drive.

Linux requires a 32-bit CPU and a memory management unit, something the puny microcontroller doesn’t have. For [Dmitry], the best course of action was emulating an ARM processor on an AVR. We’re not sure if we’re dealing with genius or madness here, but it did prove to be a valuable learning exercise in writing a modular ARM emulator.

How fast is it? [Dmitry] tells us it takes two hours to boot up to a bash prompt, and four more to load up Ubuntu and login. If you want a Megahertz rating, good luck; the effective clock speed is about 6.5 kilohertz. While the worst Linux PC ever won’t win any races, its simple construction puts it within the reach of even the klutziest of hardware builders; the entire device is just a microcontroller, RAM, SD card, a few resistors, and some wire.

If you’d like to build your own worst Linux PC, [Dmitry] has the firmware and disk image available to download. If you want to watch the time-lapse of this thing booting, check out the video after the break.

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Tubular POV display

[Ryan]‘s cylinder POV display is an amazing piece of work. Right now it’s impressive sitting on his workbench, but we’re sure it would be astonishing hanging above the middle of a dance floor. There are 64 RGB LEDs on this display and they’re certainly bright enough to liven up any space.

Power is provided through a slip ring. The ground is connected to the shaft of the motor [Ryan] picked up at an auto parts store. It’s an efficient way to do things, but the display can only be controlled by whatever image is stored in the ATMega1284′s flash memory. [Ryan] admits this isn’t an ideal setup so he’s working on a ZigBee or Bluetooth connection.

We’ve seen some amazing spinny POV cylinders, but [Ryan]‘s build looks amazingly professional. All the board files, schematics and code are uploaded, as well as an image converter for BMPs and PNGs. Check out the demo after the break.
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Bobuino: Arduino based on ATmega1284 + goodies

[Erik] wrote in letting us know that he just completed development of the Bobuino, a Arduino based on an ATmega1284. That chip is nice and beefy, most notably for having 16 KB of SRAM but it also boasts 4 KB of EEPROM, and 128 KB of program memory.

But the upgraded chip isn’t the only thing that it brings to the table. It’s easy to spot the on-board SD card slot in the image above. Also of note is the battery-backed DS1307 real time clock with a jumper that will route the square wave output to one of two pins on the microcontroller.

This design is compatible with standard Arduino shields thanks to the familiar pair of pin sockets, and can still be programmed via the USB socket. Since the AVR chip has more IO than normal there’s also pin headers to break out the PORTC pins, for a JTAG connector, and for an RS232 port.