The sensor ports on the NXT support a serial digital protocol called I2C, which was developed by Philips in the 1980’s for use in consumer electronics (in television sets, for example). This article describes the use of a simple I2C chip that provides 8 digital I/O ports with the NXT.
Each one of these eight ports can be used as either input or output (and in some restricted ways also as both). These inputs and outputs are binary: they are either on or off. Input ports can be used for touch sensor (switches), for example. Output ports can drive LEDs, and through relays or other devices they can turn motors on or off. In the setup that this article describes, two ports are used to drive LEDs, two other ports are used as inputs, connected to push switches, and four ports remain unused.
Interfacing I2C Chips To The NXT: [Link]
The circuit seems to be very popular because it is so simple and still has a very useful and practical application and It is considered by some the perfect circuit to get started with AVR microcontrollers.
This thermometer can be used as a standalone thermometer with LCD display or it can be read out with a PC running Linux, Windows, MacOSX or solaris. BSD Unix and others are probably also possible to use for reading the temperatures. No special drivers are needed.
Simple Digital Thermometer: [Link]
The aim of the following project is the construction and development of an interface between a CMOS camera and a computer. The interface will allow a use to get images from the camera and to change the properties of the camera as brightness, luminance, etc. from the computer. Also some image tracking technology is implemented allowing the camera to track white objects and follow them with a servomotor.
The interface is based on the Atmel AVR ATmega16 microcontroller. The Camera called c3088 uses a CMOS image sensor OV6620 from Omnivision . It has a digital video port that supplies a continuous 8/16 bit image data stream. All the camera functions, such as exposure, gamma, gain, white balance, windowing, can be changed through I2C interface by writing in some registers.
The communication from the microcontroller to the camera to change the properties of the camera is made using the I2C. The images from the camera are read following the Zoom Video Port Format implemented by the camera. The images read are in black and white because only the Y channel is read. To control all this communications the microcontroller is connected to the computer via serial port. The microcontroller read commands from the computer and perform the appropriate actions. The serial port is also used to receive the images in BMP format. If you would like to start building this project, head to authors page for full info.