Any I²C device can be attached to the common I²C bus and can talk to the other devices by passing information back and forth. This device can be an I/O expander, A/D or D/A converter, LCD driver, Real-Time clock, EEPROM, LED controller, etc. Each device is addressed individually by software. An I²C device is identified by a 7 or 10-bit address that is unique to each device. This address can be partially fixed and partially programmable or fully fixed. The advantage of the partially programmable address is that two or more of the same device can be used on the same bus. For 7-bit devices, typically the first four bits are fixed. The next three bits are set by hardware address pins (A0, A1, and A2) that allow the user to modify the I²C address allowing up to eight of the same devices to operate on the I²C bus. These pins are held high to VCC through a resistor or held low to GND. 112 different addresses are possible with the 7-bit format (others reserved) and an additional 1,024 addresses are available with the 10-bit format. With programmable pins several of the same device type can share the same bus. Because of this flexibility, new devices or functions can be easily “clipped" on to an existing bus. Addresses can be assigned for a fee by the NXP I²C-bus committee or an existing or similar address can be used without cost.