Barry Carter put together a how to on building your own USB midi keyboard. He used the discontinued (read cheap) AN2131 developer board and a cheap toy keyboard. The keys are rewired with a diode based keyboard matrix that connects easily to the dev board. He rounds out the write up with some source code.
Shane brennan sent in his groups final CE/EE senior design project. fre3space is an ir, ultrasonic 3d mouse. Three towers take ultrasonic sound measurements to calculate the position of the mouse. button clicks are transmitted in ir. A fpga developers kit ties it all together and provides the usb interface. a simple opengl application demonstrates the 3d capabilities of the system (vs 2d of the desktop variety).
[Tom] was looking for a standard USB interface for a Palm folding keyboard when he stumbled across this Morse code adapter (cache) from 2004. Palm keyboards use a serial connection to talk to the PDA. Since they are low-power and compact, they’re a good choice for ham radio applications. The site has pictures, schematics and PIC code to make the Morse code keyboard.
[Ram Sripracha] thought it was mighty odd that his new bluetooth Mighty Mouse had an LED that was constantly on when the mouse wasn’t moving. He decided to pop the case open and see what the current draw was. When the mouse is moving the LED is off and the current draw is ~.0285 amps; when the mouse has stopped the LED is on and the current draw is ~.0450 amps. He removed the LED to create a lower power bluetooth Mighty Mouse that only uses .0017 amps when not moving. So, 3.8% of the power that was originally consumed while sitting still.
Master modder [Jani ‘Japala’ P?? latest hack is adding an LCD screen into a mouse. The LCD is from a Nokia 6610. It fits pretty well since the controller board isn’t any larger than the screen. The controller requires adding three more wires to the mouse. These are connected to a parallel port. The screen can only show about 1 frame per second, but that is fast enough for general statistics or showing photos. It’s a really clean build. A clever trick was using a piece of plastic from the blister pack to cover the screen since it was already the same shape as the mouse.
[thanks z]
Hack-A-Day regular [Andrew] has posted an incredibly simple game port based photogate. He uses a pair of light dependent resistors. Each one is placed inside of a ballpoint pen tube to limit ambient light on the sensor. He’s got a simple QBasic program to calculate the velocity of an object passing the sensors. You’ll have to run it inside a DOS emulator to get access to the game port under XP.
I2C is a simple communications bus similar to 1-wire, which we’ve talked about earlier. [hnch] has built a really simple I2C parallel port interface. It’s optically isolated so you don’t have to worry about a mistake frying your computer. I2C modules already come with the Linux kernel. It will even treat temperature sensors you attach exactly like the ones you have on your motherboard so you can monitor them using ordinary software like gkrellm. There are lots of other devices that use I2C as well. [hnch] has a nerdity gallery and will gladly write up any other project you’d like information on.
Continue reading “Optically Isolated Parallel Port I2C Adapter”
