Hardware Reference
In-Depth Information
chemicals, or fabricated professionally. Luckily, when prototyping, you don't
need to do all that; there is a much simpler alternative: the breadboard.
Use of the term breadboard in this discussion may surprise you; normally it
is a l at, wooden board designed to cut bread (or other foods). In the early days
of amateur radio, amateurs would nail bare copper wire onto a wooden board
(more often than not a breadboard which was readily available), and solder
components onto the wires. Because components were much bigger in those
days, some components (tubes especially) could actually be screwed onto the
breadboard. Amateurs had created an easy prototyping device from an item
readily available at any supermarket.
Modern breadboards are sometimes called solderless breadboards , implying that
they can be reused. They exist in all sizes, from the smallest boards, designed
to hold a single component, all the way to huge prototyping boards, designed
to include an entire single board computer. Breadboards are normally classed
by their number of connection points , the number of holes on the board that can
accept wires and components.
Typical breadboards have two areas called strips . The terminal strip is the
main part of any breadboard and is designed to hold components and wires.
There is normally a notch in the middle, marking a separation between con-
nectors, but it is also designed to allow air to l ow beneath components helping
them cool down.
The terminal strip is normally numbered: numbers horizontally and letters
vertically. What is important to know is that a single number is connected to all
the letters; A0, B0, C0, D0, and E0 are all connected electronically. A component
pin placed in E0 connects to a wire connected to A0 but does not connect to a
wire placed in A1.
The bus strip is located along the side of the terminal, and serves as a power
rail. Normally, two rows are available: one for the supply voltage and one for
the ground.
The holes are not placed at random; their spacing is exactly 0.1”, or 2.54 mm,
accommodating many electronic components, and all Dual In-Line Package
(DIP) chips. Most of the AVR chips exist in DIP format, making it possible to
build an Arduino directly on a breadboard.
Inputs and Outputs
The Arduino's digital pins can be coni gured to be inputs or outputs to either
write information or to read it.
There are two types of inputs on Arduino boards, digital and analog. On
the digital pins, the Arduino “reads” either a logical zero (0 volts), or a logical 1
(equivalent to the power supply of the Arduino itself). Most Arduinos are pow-
ered by 5 volts, but a few are powered by 3.3 volts. If using a 3.3 voltboard like
the Due, don't put 5 V on an input pin; you could damage the microcontroller.
 
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