Operation Manual

Human-computer interfacing
129
Notes:
Don’t worry, though, if you had your heart set on creating some real-time
applications. There is another small electronics prototyping platform, called an
Arduino, which contains a programmable microcontroller suitable for real-time
applications. It is quite easy to use a Raspberry Pi and an Arduino board together.
An Arduino can be used for the high-speed, real-time parts of the design and
a Raspberry Pi can run a higher-level GUI or web application that controls
the Arduino.
Although the Raspberry Pi can run fast I/O applications and the Arduino can use
web applications, this is not what they are best suited for. Remember: always use
the right tools for the job! There is an example of communicating between an
Arduino and a Raspberry Pi later in this guide.
For more information about Arduino boards, see http://www.aurduino.cc
GPIO hardware interfaces on the Raspberry Pi
There are several types of interface pins on the Raspberry Pi. They can be
configured and used for lots of applications. Note that because the pins on the
Raspberry Pi board are connected straight into the system on a chip (SOC), it is
quite easy to damage your Raspberry Pi or SD card if you are not careful. Make
sure you only use 3.3V on the pins, not 5V. For this reason, it is recommended
that you use an interface board, such as the Gertboard, between the Raspberry
Pi and any circuits you build.
The maximum permitted current draw from the 3.3V pin is 50mA. The maximum
current draw on the 5V pin depends on your power supply – you must leave
enough for the Raspberry Pi to run! Pins not listed in the table above are described
by type in the sections below. Note that some pins can be configured for more
than one type of interface.
DNC = Do Not Connect.
These pins are reserved
for future use.