DIY Button Matrix Lights Up And Speaks I2C

May 17, 2019 by Donald Papp 2 Comments

[David Johnson-Davies] always wanted an illuminated button matrix for projects, but cost was never very friendly. That all changed when he discovered a cheap source of illuminated pushbuttons on Aliexpress, leading to this DIY 4×4 illuminated button matrix design which communicates over I²C. The button states can be read independently of setting the light pattern, and an optional interrupt signal gets pulled low whenever there is a change detected. Not bad for one PCB plus about $10-worth in components!

The device uses every single pin on an ATtiny88, and because each button gets its own pin the keypresses can be detected with pin-change interrupts. The state reporting of buttons over I²C is unambiguous, even when multiple buttons are pressed simultaneously. A simple protocol provides all the needed functionality, and all connections are brought to the board’s edge to allow for easily tiling multiple panels.

The GitHub repository contains the code and PCB files and [David] helpfully shared the board files to OSH Park and PCBWay for easy ordering. In addition, he provides two demos (Tacoyaki and Tacoyaki+) which are games related to the classic Lights Out to show off the matrix.

The Smart Pen

July 11, 2017 by Steven Dufresne 22 Comments

“Ugh. You mean I have to press down on the pen’s button to open it? Gross.” In this day-and-age when we can swipe on our phones and do voice recognition, there seems no reason we should have to press a button. How antiquated. So [Marek Baczynski] modernized his pen for swiping and voice control. It’s also sure to get all the kids back to working on their penmanship.

Seriously though, not all hacks have to be serious. [Marek] and [Ghlargh] added a servo to activate the button, and then [Marek] added Bluetooth to control the servo. After writing a phone app, he was able to swipe down to open it and down again to close it. Then, after some prompting from Redditers he added voice control from his laptop. We think he could have done a more professional job with the way he attached the pen to the laptop, perhaps he could have 3D printed something instead of just using tape, or maybe made something using CNC or a laser cutter. An important hack such as this deserves as much. Now he need only say “Computer. Open pen.” and the tedious task is taken care of. Seeing is believing so check it out in the video below.

Continue reading “The Smart Pen” →

Repurposing A Click Wheel

February 5, 2010 by Mike Szczys 24 Comments

We think the click wheel is the biggest contributor to the success of the original iPods. The devices were a brick with a monochrome screen but the user interface was slick and easy to use. [Jason] decided he wanted to add a click wheel to his own project. After using a logic analyzer he discovered that it doesn’t implement a common protocol such as I2C, perhaps a deliberate move by Apple to keep the controller under wraps? He managed to get past this hurdle, as seen in the video after the break, by bit-banging the data in from the click wheel and then reverse engineering the protocol.

It’s connected to an AVR ATtiny88 with feedback shown on a character LCD screen. We’re glad that [Jason] tipped us off about this, but he doesn’t have any code available yet. We love to dive into the source so the sooner he gets it up the better! We’ve got an old 3rd generation with a bad board that is begging to have the wheel ripped out of it, not to mention the dirt-cheap replacements available on ebay. Continue reading “Repurposing A Click Wheel” →