Hardware Reference
In-Depth Information
Analog Input
As discussed in
Chapter 3
, a digital pin (input or output) represents infor-
mation as either on or off. But there are plenty of inputs that could have a
range of values. Dials, sliders, temperature sensors, and light sensors are all
examples of possible analog inputs to Galileo. Along with the function
ana
logRead()
, you can have Galileo get the value of these inputs and act on them.
On the Galileo, there are six dedicated analog input pins numbered 0 through
5 (
Figure 4-5
). They accept a range of voltages from 0 to 5 volts. Since Galileo
and all computers work in the digital realm, the range of voltages must be
converted into digital data. Therefore, these input pins connect to an
analog
to digital converter
, or ADC, which is a chip that allows Galileo to read what
voltage is being sent to each pin.
Figure 4-5.
The six analog input pins are numbered 0 through 5.
Thanks to Galileo and the Arduino software, you don't need to understand
how an ADC works in order to read the value of analog sensors in your
projects.
