by Francois AUGER & Philippe Fretaud:
Many previous Design Ideas [1, 2] have shown how to use the Charlieplexing technique  to drive as many LEDs as possible with a minimum number of I/O lines. This Design Idea shows how you can drive three LEDs and scan three switches with only three I/O lines instead of six. Using the same principle, it will also be possible to manage four switches and two LEDs, or five LEDs and one switch. It works well with Atmel ATmega microcontrollers including the Arduino, and could be of particular interest for any eight-pin devices, or when you’ve simply run out of I/O.
3 pins, 3 LEDs, 3 buttons - [Link]
Here’s a pool cleaner robot built on ATmega by Davide Gironi:
My replacement electronics it is based on ATmega8 micros.
The project is divided into two parts:
The timer contains the 220 AC to low voltage DC current, and it is out of water, his purpose is to start and stop the cleaning pool robot, which of course is inside the swimming pool.
ATmega based pool cleaner robot - [Link]
Dan over at HackAday documented his single chip computer project with the PCBs from DirtyPCBs:
A single AVR microcontroller (the ATmega 1284P) has been used to create a standalone computer system which runs the BASIC programming language. The 1284P runs TinyBASIC Plus, generates RCA video signals (using TVout) and reads PS/2 keyboard input. A single sided PCB was used to hold all the components meaning it is easy to manufacture the computer at home using processes such as photo-etching. Additionally, the component count is fairly low and only one IC is required (the 1284P).
Single chip AVR BASIC computer - [Link]
I recently stumbled across an interesting fact in the datasheet for the ATMEGA32u4, the microcontroller I am using for my Einstepper Project. I was surprised to find that Atmel had included a temperature sensor in the core of the device that you can read using the internal ADC. As it turns out, there are many megaAVR devices contain an internal temperature sensor. According to Atmel’s product finder, these devices are:
ATMEGA Core Temperature Sensor - [Link]
anool @ wyolum.com builds a pulse lamp controller for the parking light of his KTM bike. He writes:
My brother is a Mechanical Engineer who loves his KTM Duke 200 bike. He asked me to build this circuit : http://sunbizhosting.co.uk/~spiral/blog/?p=227 for a ‘heartbeat’ lamp controller for the parking light. A Neutral Detect (ND) signal controls the lamp pulsing. When ND is HIGH, the Lamp is fully lit. When ND goes LOW, the lamp starts pulsing.
I’m not familiar with PIC microcontrollers, and didn’t want to dabble in “C” code. I’d be comfortable with an Arduino, but even the smallest ATMega seemed too big (and overkill) for this simple requirement. How about an ATTiny ? A bit of Googling, and I found this excellent resource for running the Arduino environment on the ATTiny : http://hlt.media.mit.edu/?p=1695
p.u.l.s.e. – fader control for Motorcycle parking Lamp - [Link]
In this article, circuitstoday.com explain the basics surrounding arduino. As the title indicates, this article is for absolute beginners in the world of electronics and for people who are beginning with arduino boards.
Arduino is an electronics prototyping platform based on a micro controller. Arduino boards are usually made using Atmel’s Atmega series micro controllers or ARM micro controllers. Arduino is an open source hardware project which means the designs of board (the hardware architecture, CAD files) are available to public with open source license. Anyone can modify the hardware designs and the associated software.
What is Arduino – Introduction to Arduino for Beginners - [Link]
Davide Gironi writes:
This library is an update of the software PWM driver you can find here.
This update implements also progressive start / stop features. So, with this one, you can drive up to 4 motors independently controlling: speed, direction, slow start / stop
Driving a DC motor using software PWM with AVR ATmega - [Link]
Bajdi documented his Arduino self balancing bot build:
For the electronics I used one of my own PCB creations, a Bajduino of course It’s just a small (50x50mm) break out board for an ATmega328. I’m running the ATmega @ 16MHz and 3.3V. It’s out of spec according to the datasheet but it works… I also needed an IMU of course. I found a MP6050 sensor in my parts box. The MPU6050 combines a 3 DOF gyro and 3 DOF accelerometer in a small package, ideal for a self balancing bot.
Building a self balancing bot - [Link]
domiflichi @ instructables.com writes:
If you’re like me, after I got my Arduino and performed a final programming on my first chip, I wanted to pull it off my Arduino Duemilanove and put it on my own circuit. This would also free up my Arduino for future projects.
The problem was that I’m such an electronics newbie that I didn’t know where to start. After reading through many web pages and forums, I was able to put together this Instructable. I wanted to have the information I learned all in one place, and easy to follow.
Standalone Arduino / ATMega chip on breadboard - [Link]
Mizchief100 @ instructables.com writes:
I love robots. Normally the ones I build are quite large and wouldn’t fit in your pocket, but for a change of pace I decided I would try something small and fun! This robot is exactly that, and in fact fits inside of an altoids tin. It is inexpensive, versatile (so many different sensors can be used), and extremely entertaining. Check it out in action below! (Unfortunately I played with mine so much before I took any video I had used up my coin cell batteries and one motor started having issues, so I’m driving it with a 9V in the video)
Tiny Altoid Tin Robot With Personality - [Link]