Hardware Reference
In-Depth Information
Introducing Wire
Connection wires I
2
C, short for Inter-IC bus, is a serial bus designed to enable
access to numerous devices. The Arduino's hardware serial bus can connect
only to one device at a time, and SPI (see Chapter 7) can talk to three devices.
In 1982, Philips created the I
2
C standard, capable of addressing hundreds of
devices, using only two wires. It was i rst used to connect peripherals together
in a television set, but since then, I
2
C has been used in cars, computer systems,
and hobbyist electronics, to name a few. It is an easy and inexpensive way to
interconnect dozens (if not hundreds) of devices on a same network.
Originally, only a few I
2
C devices existed, but today there are hundreds of
devices. Temperature sensors, pressure sensors, accelerometers, displays, and
even EEPROM memory can all be accessed by I
2
C, using simple reads and writes.
An EEPOM device controlled by I
2
C is illustrated in Figure 8-1.
Figure 8-1:
I
2
C EEPROM integrated circuit
I
2
C is based on a master slave system; the master addresses slaves and requests
information. The slave then replies and remains silent until again asked to com-
municate by the master. The original I
s
C specii cation allowed communications
Search WWH ::
Custom Search