Ted Yapo had a small problem. As an amateur atronomer and astrophotographer, he needed a way to mark his expensive equipment so that he wouldn’t trip over it in the dark. Glow-in-the-dark materials were out because of they only glow for a short time, and glow sticks were also less than ideal because of their single-use nature. Tritium light sources would be perfect, barring the small details that they’re radioactive, expensive, and in the US only a few uses are allowed, most are prohibited by law.
So Yapo instead came up with an LED light that can run for not 20 hours, or even 20 days, but 20 yearson a single CR2032 coin cell battery!
This project evolved from Splinter, the SMT cordwood project I did last summer/fall. The ring is powered by tiny size 10 hearing aide batteries which should give 4-6 weeks of intermittent use, once I come up with a design that doesn’t break after a few days of wear and update the firmware to put the ATtinyx5 to sleep. The first rev (labelled ‘blink-ring’) used deep red 650nm LEDs. Searching for particular component lengths gave me an excuse to use strange 0508 resistors. And somehow, this is my first Charlieplexing project. Yaay novelty soldering!
One reason is to take advantage of standardized, open source creativity. Anyone can share a model of their design for all to use as is, or to modify for their needs. A case in point is the ball and socket model which I downloaded for a helping hand. I then drew up and printed a magnifying glass holder with a matching socket, made a variation of the ball and socket joint, and came up with a magnetic holder with matching ball. Let’s take look at what worked well and what didn’t.
Our guests for this week’s Hack Chat are Pete Dokter and Toni Klopfenstein of SparkFun Electronics. Pete is formerly the Director of Engineering at SparkFun and now the Brand Ambassador for SparkFun Electronics.
He hosts the According to Pete video series expounding on various engineering principles and seriously needs a silverburst Les Paul and a Sunn Model T. Toni is currently the product development manager at SparkFun. She’s served on the Open Source Hardware Association Board and participates in the Open Hardware Summit yearly. In her free time, she spends fifty weeks out of the year finding dust in her art and electronics projects.
The Micro:bit is a pretty decent platform for teaching kids to program, but you can’t really make arcade-style games for it. You only have two buttons and a 5×5 display. Perhaps enough for a very small snake game, but that’s pretty much it. That’s why I started working on #PewPew FeatherWing as an alternative platform, but at some point I started wondering if it’s really impossible to do it on the micro:bit.
When the most recent version of micropython got the ability to use any pins for I2C, I realized that I can finally connect a display easily. I could use a HT16K33 and a 8×8 LED matrix like on the PewPew, but I decided to try something else — a monochrome OLED display, similar to the one used on many Arduino-based game consoles.
This project is based on my #reDOT project. Basicly it is a 5×7 SMD LED Matrix an a microcontroller on one PCB. I started wirh 0201 LEDs (see first project log), but this was not reliable. So a second version with 0402 is in development. 0402 LEDs do have some benefits over 0201:
bigger and you can solder them better
more colors availible
The microcontroller (a low coast STM8) drives all LEDs directly with multiplexing. For controlling a UART interface is available. The dimensions are like a DIP-6 package. For easy connection of multiple PCBs, the pads are castellated. Also the supply rails are available on both sides. So multiple of these display can be soldered together to a bigger display without the need of additional wiring.
This is a small blinky with 20 LEDs powered by one CR2032 coin cell
and with an ATTiny45 brain. The firmware is written in plain C and
compiled with the avr-gcc toolchain. The PCB is a two layer design made