Laptop Trackpads and MIDI Controllers


A bunch of pads connected to a MIDI out port is as old an idea as the Akai MPC. creating a homebrew version is great, but [Scott] took his version one step further. He used old laptop trackpads to control note on and note off commands when the each pad is tapped, and also added MIDI CC values for the touch pressure and the x and y-axis position.

The trackpads were identical models, each having their own PS/2 output. A few ribbon cable to 8-pin header adapters were manufactured, and the entire ensemble encased in a wonderful maple and aluminum enclosure.

The electronics are based on an Arduino Mega with 16 clock and data points for each touchpad eating up 32 of the 54 available pins on the ‘duino. The PS/2 protocol is well documented, but running 16 separate PS/2 id most certainly not. [Scott] ended up writing his own asynchronous PS/2 communications library to get the latency of his midi device down to about 50ms.

It’s an amazing bit of kit and comparatively inexpensive, given that [Scott] now has a 16-channel Kaoss pad. Video of the device hooked up to a MicroKorg below.

Continue reading “Laptop Trackpads and MIDI Controllers”

Hackaday Links: Sunday, May 5th, 2013


Let’s start off this weekend’s links post with some advertising. We like targeted ads (mostly because we don’t have pooping problems and are tired of hearing about Activia). So we applaud IBM for finding our number with this commercial which produces a stop-motion animation using single atoms as pixels. Wow! [via Reddit and Internet Evolution]

Speaking of commercials, here’s some snake-oil which lets you touch a boob without being in the same room with the person [Thanks Michael].

Moving right along we’ve got a trio of trackpad hacks. There’s one that lets you use the keyboard and trackpad of a MacBook as a standalone USB input device [via Reddit]. Or you could take a Toshiba laptop to the tablesaw to turn it into a USB trackpad. But maybe your Acer C7 Trackpad doesn’t work very well and you just need better grounding.

[Nick McGill] is a member of the team developing an upper body exoskeleton as an assistive technology. This made the rounds on tech websites but the lack of in-depth build info on the project site kept it from getting its own feature here.

If you have a router capable of running DD-WRT here’s a method of setting up a PPTP VPN for free.

And finally, you may remember hearing about the original Prince of Persia source code being discovered and released about a year ago. Well [Adam Green] figured out how to compile it into the original Apple II floppy disks. [Thanks Arthur]

A Bluetooth trackpad from a resistive touchscreen


If you’ve checked out your favorite online retailer of absurdly inexpensive Chinese electronics, you’ll find a whole bunch of replacement parts. Phone parts are especially common, with high-resolution LCDs available for just a few dollars. There are also a few touchscreen kits – resistive touchscreen digitizers that can easily be read with a microcontroller. [Vinod] got his hands on one of these touchscreen digitizers, and with the help of an 8-pin micocontroller turned it into a Bluetooth trackpad.

The clear plastic touchpad is a relatively simple device. By reading a pair of analog values, it’s easy to find the coordinates of a finger or stylus on the touchpad. [Vinod] programmed an ATtiny13 to read these values and turn them in to x y coordinates, but he needed something useful to do with this data.

By connecting a small bluetooth module to his microcontroller, [Vinod] could send these coordinates to his computer. The result is a homebrew touchpad, able to move a cursor around, left and right click, and emulate a scroll wheel.

Continue reading “A Bluetooth trackpad from a resistive touchscreen”

Replace batteries with USB power

[Mark Bog] thought it was a waste to use batteries for his desktop touch pad. Quite frankly we agree that if you can avoid using disposable cells you should. He ditched the dual AA batteries inside of his Magic Trackpad and built a battery-sized adapter to feed it some juice. It consists of a dowel of similar diameter with a screw in each end. He scavenged a USB cord, connecting hot and ground wires to the corresponding pole of the adapter. Now his Trackpad is USB powered and never in need of a battery replacement or even a recharge.

We’re not familiar with the inner workings of Apple’s Magic Trackpad. We assume there’s a voltage regulator inside and we hope it doesn’t have a problem working with the 5V regulated power coming in from the adapter. If you’ve got the skinny on the hardware we’d love to hear about it in the comments. One last thing: because the forum linked above requires a login to view the images in the post, we’ve embedded the rest of them after the break for your convenience.

Continue reading “Replace batteries with USB power”

Tiny keyboard/touchpad has “hack” written all over it

Yes, we know, this is not a hack, yet it just has the vibe of something we’ll likely be seeing in many small form-factor systems and wearable hacks in the future.

The USB Wireless Handheld Keyboard is a diminutive keyboard and mouse replacement with a passing resemblance to a BlackBerry PDA — where the screen has been replaced with a laptop-style trackpad sensor. This seems a shoo-in for home theater PC use; it’s unobtrusive and won’t look out of place on the coffee table alongside the universal remote. But any tiny system requiring only occasional input could likely benefit.

The keyboard layout is funky as heck, though likely adequate for its intended use of couch web-surfing and interactive messaging (or whatever wild applications our readers will surely come up with). A USB wireless receiver and a charging cable are included in the $62 package. Video after the break…

[USB Geek via Engadget]

Continue reading “Tiny keyboard/touchpad has “hack” written all over it”

Touchpad and VFD hacking

p2 (Custom)

[Agent420] brought up this touchpad and VFD hack in the comments on our capicitive sensor guide post. He had broken dell laptop from which he harvested the touchpad and an HP laserjet that contributed the VFD. Though the touchpad communicates using standard PS2 protocol, he wanted to use it with his Atmel 8535 AVR which required him to write some custom code. In the picture above, you can see the VFD displaying the coordinates of his finger. You can download his code as well as the spec sheets for the different pieces on the project thread.

Plexi cliffhanger for trackmate


If you’ve ever wanted to play with tangible tracking systems quick and cheap, you might be interested in this super quick tracking surface for trackmate. Trackmate is open source software for physical object tracking. Making a surface for it isn’t that hard in the first place but this one is probably the easiest.  All you really need is some Plexiglas, some c-clamps and a web cam. The whole thing packs into a backpack or over the shoulder bag. This would be perfect for live performances.