Ken has two dogs, one of them ‘sunshine’ likes to run around when given the chance to go out. This gives him worries since she could be hit by a car. To lessen his worries he rigged up a bunch of LEDs into a dog collar. The LEDs are connected to an AVR ATTINY2313 microcontroller.

Current limiting resistors are used to regulate current that flows through the LEDs. The entire electronic set up including the ATTINY2313 and the LEDs are powered using 3 AAA batteries. The PCB was made using toner transfer method while an arduino was used as an ISP to program the ATTINY2313. The good thing about building DIY stuff in your home is that what ever you do you always find a way to utilize hot glue – the electronic components in the board is covered with hot glue, the LEDs are helt to place by hot glue and the PCB was mounted on the collar with [what else?] HOT GLUE!

While driving his car to pick up his wife Scott suddenly got an idea for a fun project to build. Inspired by the flashing of another vehicle’s emergency lights he planned to do an experiment on wireless data transfer between a microcontroller and his personal computer

Using a pair of photodiodes, a couple of transistors and a few resistors to serve as the sensors for his microcontroller, Scott was able to read data from a strip of black and white lines. When the photodiode passes a black strip it reads 0 while 1 for a white strip – this is following the reflection principle.

At first, he was using digital inputs however he ran into a few problems since the intensity of reflected light could either give all 1s or all 0s – to fix this he used an analog to digital converter (ADC) channel and used a range comparison – example 200-255 will be 1 while 199 below is zero.

During test, Scott was able to read the entire black and white strips and have them displayed using java script.

HackSkunk had and assignment to develop simple system that would allow to detect when sisters son leaves his place at night. So he came up with prototype of motion detector based buzzer alarm based on Attiny85 microcontroller. As circuit has to be active only at night so he put a LDR resistor that cuts power in daylight.

The other principle is obvious – microcontroller simply gets trigger signal from motion sensor and then rises alarm on buzzed. No more sneaking around!

Building an electronic dice is a piece of cake especially when MCU has sufficient number of I/O pins. But why waste powerful microcontroller for such simple task. It is possible to drive more LEDs than there are pins available. So using 5 attiny13 pins Mike specially connected 14 LEDs so they can be controlled like he wants.

Dice is triggered with single button and that’s it what you need. If you dig deeper you’ll find a nice description of working concept and of course ASM code that is quite rarely used these days.