A Charlieplex display and a board layout tip

[Ben] is getting himself up to speed with microcontrollers. He jumped into the deep end by taking on this Charlieplex LED matrix build. As you can see after the break, he not only made the display work, but coded Conway’s game of life to run on the ATtiny85 that drives the device. What you see above is the prototype version that [Ben] used to make sure he had the hardware just right. He’s seeing the project through to a manufactured board and this is where the layout tip comes from. In order to make sure he had enough space for all of his components he printed out the board artwork, taped it to some Styrofoam, and then inserted all of the through-hole parts. Now he can be sure that physically the design works, we’ll keep our fingers crossed that everything is also kosher electrically.

[Read more...]

Conways’ wall of life and whiteboard emporium

White board beats chalk board, LED marquee beats white board, and an LED white board trumps them all.

This hybrid lets you draw on the surface with dry erase markers while Conway’s game of life plays out underneath. [Bert] sent us this tip after seeing yesterday’s office marquee. This version is quite similar in appearance but the guts are very different. Inside you’ll find a Parallax SX28 microcontroller doing the heavy lifting. The display is multiplexed but they didn’t go with a common 595 shift register, but a beefier MAX6979 LED driver. We’re not too familiar with this part but it does have a lot of nice features like constant current, and automatic shutdown if serial data stalls for more than 1 second. This is a low-side driver so transistors are used to connect voltage to the rows; the opposite from the setup we looked at yesterday. This was built several years ago and is still working happily even though its permanent home is a breadboard. Source code can be found on this page.

Communicating with an LED matrix

Most of the LED matrix posts we run delve into the hardware design. This time around [J Bremnant] used prefab modules and focused on writing code to address the display. The hardware combines two 24×16 LED boards from Sure Electronics with a Teensy 2.0 to drive the display and provide a USB connection. The firmware comes in just under 8k, leaving graphic manipulation up to a PC.

[J Bremnant's] Python script offers a lot of flexibility when working with the display. There are three modes selectable through a terminal interface. One just tests the display and then drops into Conway’s Game of Life. The second mode lets you send commands via serial interface so it can be used as a message ticker. The final feature is frame addressing that allows graphics to be dropped into the display. See each of these featured in the video after the break.

[Read more...]

Reboot Life in a heartbeat

This hoodie senses your heartbeat and uses it to control Life. Conway’s Game of Life, popular in all kinds of electronics projects, uses a grid of cells coupled with a set of rules to mimic the life and death of simple organisms. This iteration displays the game over your own heart, then taps into your heart rate, resetting the game at the beginning of each cardiac cycle. We guess you could say that Life goes on only if you do not.

The EKG circuit that detects the heartbeat is made up of an IR transmitter shining through the tip of your finger to a receiver. An ATmega168 running the Arduino bootloader controls the EKG circuit and resets an ATmega48 which is responsible for Life. [Joe] admits that this is overkill but he’s currently without an AVR programmer; he went this route to make it work. The stylishly-geeky hoodie is taken for a test run (er… test-hop?) after the break.

[Read more...]

Capacitive buttons control all life

capacitive_game_of_life

Projects involving Conway’s Game of Life and utilizing a Nokia 3310 screen are quite popular with electronics hobbyists. [Droky] put these two together and went one step further by adding capacitive sensors to control the Game of Life. His work is a great example of how to use the Atmel QTouch capacitive sensor (QT100a datasheet). This chip does the heavy lifting that we’ve seen in other touch sensitive solutions. It operates from 2V-5.5V, requires only three capacitors and a resistor, has a one pin active high output, and sells for around $1 in low quantities. One thing [Droky] overlooked in his board layout is the ground pad on the bottom of the WSON6 chip. He was able to make it work by masking the trace that runs under the chip but you will want to alter the layout in your own designs.

If you’ve used the QT100a before we’d like to hear about your experience, and find out if button debounce handling is necessary with this chip. Let us know in the comments. You can see a video of it in action after the break.

[Read more...]

LED Life and Charlieplexing


Yesterday, we featured [Andrew]‘s orientation aware camera. We want to highlight another one of his projects: LED Life. It’s a 6×5 LED matrix playing Conway’s Game of Life. He used the low power MSP430 like our e-paper clock. The best part of the writeup is his explanation of how Charlieplexing works. Microcontroller GPIO pins generally have three possible states: output high, output low, and input. This combined with the directional nature LEDs and some creative wiring means you can run a large matrix of individually addressable LEDs with just a few IO pins. Instead of just flipping the IO pins on and off you change their assigned state. Have a look at [Andrew]‘s site for some great illustrations of how the system works. A video of his LED Life board is embedded below. [Read more...]

Follow

Get every new post delivered to your Inbox.

Join 93,799 other followers