Hardware Reference
In-Depth Information
Hobby Specialists
In addition to the major chains, there are smaller companies that specialise in working with
hobbyists. Although their selection is dwarfed by those of the larger chains, it's typically hand-
picked and comes with the personal recommendation of the people behind the company.
Many of these hobby shops sprang up in the wake of the Arduino, an open-source project to
create an educational-friendly microcontroller prototyping platform. With the Raspberry Pi
appealing to much the same audience as the Arduino—albeit for very diferent tasks—the
majority are investigating support for the Pi in addition to their existing product lines.
Buying from a hobby specialist has several advantages. If the products are sold as working
with the Pi, then they've been tested for that speciic reason—taking much of the guesswork
out of the equation. Several companies also design their own add-on hardware for various
platforms, with the Pi being no exception. hese devices, designed to address a need in the
community, may include additional ports and/or extra hardware, or can otherwise extend
the functionality of the target device.
In the UK, one of the most popular hobby specialists is oomlout. Founded by open-source
enthusiasts working with Arduino hardware, it's an excellent source of add-on kits as well as
common components including push-buttons, displays and transistors. Unlike the larger
retailers, oomlout equips its components with all necessary extras—such as pull-up resistors
for the push-buttons—and a circuit schematic for easy assembly. Where possible, sample
source code is also provided to get you up and running as quickly as possible.
In the US, Adafruit ofers a similar service. Founded with the intention of making open-
source add-ons for the Arduino boards, Adafruit ofers a wide selection of components and
kits—including one of the irst add-on boards designed speciically for the Raspberry Pi (see
Chapter 13, “Add-on Boards”, for more details).
he websites for both retailers can be found here:
oomlout:
http://www.oomlout.co.uk
Adafruit:
http://www.adafruit.com
The GPIO Port
he Raspberry Pi's GPIO port is located on the top-left of the printed circuit board, labelled
P1. It's a 26-pin port, itted with two rows of 13
male 2.54 mm headers
at the factory. he
spacing of these headers is particularly important: 2.54 mm pin spacing (0.1 inches in impe-
rial measurements) is a very common sight in electronics, and is the standard spacing for
prototyping platforms that include stripboards and breadboards.
