I am working on a data logger for the wii nunchuck. I need something to record the accelerometer values that get output from the nunchuck. I had a Microchip 25LC080 eeprom handy and decided to hook it up to my Arduino.

The Arduino site has a great tutorial on working with serial eeproms http://www.arduino.cc/en/Tutorial/SPIEEPROM . I used it to get most of my information. The eeprom I am using is a just little different than the one in the tutorial.

The Wiimote makes a perfect control system for a fire fighting robot.

It has IR sensors which can detect a candle and a bluetooth transciever to communicate back to a host computer. I use a boebot as the robot platform, an arduino, wiimote and a Linux computer.

With a little hacking, data can be read from a wii nunchuck directly into an Arduino, using TWI (aka I2C). The nunchuck contains a 3 axis accelerometer, joystick and buttons for only $19.95. The same accelerometer in kit form, cost $34.95 at Sparkfun. Plus the nunchuck is already wired up in a nice clean case! So the wii nunchuck should fit nicely into anyones robotic project.

After some trying, I have been able to use a wiimote for two-way communication for an Arduino. So far I just have a proof of concept. The code is very rough. For the set up and wiring, first look at my earlier entry on using the wiimote for one way communication.

I recently switched from using plain Atmel chips to Arduino. Arduino is a development platform that uses an Atmel Atmege168 chip. It simplifies things a lot.

The Arduino board has a USB port. It has a built in FTDI chip for USB to serial conversions.

This HOWTO shows how to communicate between Perl/Linux and the Arduino. Because of the Arduinos FTDI chip, I can use regular serial communication, I just needed to first set up the USB serial adapter drivers. Most modern linux distro should come with them installed.

The perl script will transmit a number, starting at 0, to the Arduino. The Arduino will then echo that number back to your linux/perl computer.

With a little wiring a Wiimote can be made into a cheap bluetooth transmitter for your microcontroller project. Wiimote peripherals like the nunchuk, communicate with the wiimote over I2C (aka Two Wire Interface, TWI). A number of microcontrollers support TWI, such as the Arduino,the Make Controller and Atmels ATmega series. I am using an arduino with a ATmega168 for this project.

Here is how I controlled a stepper motor with an Atmel attiny2313. I found an old stepper motor in my junk box. I remembered it was a unipolar stepper but that was about it. Google couldn't find the part number, so I had no data sheet.

A unipolar stepper motor has four magnet/coils. Each coil must energize in sequence to spin the motor. The coils are in pairs. Each pair shares a common positive line.

The motor has 6 wires so I had to figure out what each was. The colors where: white, black, blue/red, white/blue, white/black. I pulled out my meter and checked the resistance between each set of wires.

The attiny2313 has a built in UART for serial communication. You need a few outside parts to allow it to communicate with a PC over a serial connection.

This article demonstrates how to use a Microchip 25LC080 serial eeprom with an attiny2313. The code was written using gcc. This code will write one byte to the eeprom, then read it back in.

Using a shift register latch can increase the number of output pins your AVR can use. It takes 3 avr pins to control a 74HC595N latch. The latch in turn controls 8 output pins. The latches can be daisy chained togther. So your 3 avr pins can control multiple latches greatly increasing the number of output pins available.

The 3 avr pins that connect to that latch are pins: 14 (serial input pin), 11 (clock pin) and 12 (latch). You must first shift the bits into the latch. First set pin 14 either high or low, then set pin 11 high. This sets the first bit. You repeat this 8 times to shift in all 8 bits. After the last bit you set pin 12 high and the output pins of the latch are activated. I also connected VCC to pin 16 of the latch. The diagram below doesn't show that. I used Eagle to design the circuit and their library did not show pin 16 for some reason.