In future articles we will see how we can build our own I2C devices, how to interface a Raspberry Pi and an Arduino using I2C and how to do some advanced I2C configurations, including using multiple masters on one I2C bus. This will be the first of four articles on I2C. We’ll also see how it can be used to exchange information between two Arduinos and how it can be used to allows one Arduino to control another one. Today we will correct that and learn more about I2C. There is a guide to using it from an independent source.Although we have used many I2C sensors and displays in previous articles we have not actually looked into how I2C works and how it can be used to communicate between microcontrollers. The interface cost $8 in kit form at 2/2010. Alternatively, they can be accessed through an interface which costs a little money, but reduces the workload inside the Arduino. MicroLans can be accessed directly by an Arduino, using the mature Arduino OneWire library.

Many 1-Wire chips can operate in both parasitic and normal power modes. The sample code below demonstrates how to interface with a 1-wire device using Jim Studt's OneWire Arduino library, with the DS18S20 digital thermometer as an example. They are more tolerant of long wires between sensor and Arduino. The 1-wire temperature sensors have become particularly popular, because they're inexpensive and easy to use, providing calibrated digital temperature readings directly. but it may also answer questions and inspire interest. (Devices drawing power from the 1-wire bus are said to be operating in parasitic power mode.) Tom Boyd's guide to 1-Wire may tell you more than you want to know. On a 1-Wire network, which Dallas has dubbed a 'MicroLan' (trademark), a single 'master' device communicates with one or more 1-Wire 'slave' devices over a single data line, which can also be used to provide power to the slave devices. There are no fees for programmers using the Dallas 1-Wire (trademark) drivers. It also needs a cleaning of the library paragraph that includes references to older versions of libraries.) Dallas Semiconductor (now Maxim) produces a family of devices that are controlled through a proprietary 1-wire protocol. 1-Wire Protocol (This page still needs some more generalisation to 1-Wire, as some code is specific to 'using the DS1820' and a specifc LCD.

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