AIM: a. To identify the parts of Arduino board
APPARATUS:
1. Arduino Uno Board – 1 No.
2. LED - 1No.
3. Resistor-100 Ohm -1 No.
4. Bread Board – 1 No.
5. Connecting Wires
6. USB Cable.
THEORY:
There are many varieties of Arduino that can be used for different purposes. Some boards look a bit
different from the one below, but most Arduinos have the majority of these components in common:
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Power (USB / Barrel Jack)
Every Arduino board needs a way to be connected to a power source. The Arduino UNO can be
powered from a USB cable coming from your computer or a wall power supply (like this) that is
terminated in a barrel jack. In the picture above the USB connection is labelled (1) and the barrel jack is
labelled (2).
The USB connection is also how you will load code onto your Arduino board. More on how to program
with Arduino can be found in our Installing and Programming Arduino tutorial.cccccp
NOTE: Do NOT use a power supply greater than 20 Volts as you will overpower (and thereby destroy)
your Arduino. The recommended voltage for most Arduino models is between 6 and 12 Volts.
Pins (5V, 3.3V, GND, Analog, Digital, PWM, AREF)
The pins on your Arduino are the places where you connect wires to construct a circuit (probably in
conjunction with a breadboard and some wire. They usually have black plastic ‘headers’ that allow you
to just plug a wire right into the board. The Arduino has several different kinds of pins, each of which is
labelled on the board and used for different functions.
• GND (3): Short for ‘Ground’. There are several GND pins on the Arduino, any of which can be
used to ground your circuit.
• 5V (4) & 3.3V (5): As you might guess, the 5V pin supplies 5 volts of power, and the 3.3V pin
supplies 3.3 volts of power. Most of the simple components used with the Arduino run happily
off of 5 or 3.3 volts.
• Analog (6): The area of pins under the ‘Analog In’ label (A0 through A5 on the UNO) are
Analog In pins. These pins can read the signal from an analog sensor (like a temperature sensor)
and convert it into a digital value that we can read.
• Digital (7): Across from the analog pins are the digital pins (0 through 13 on the UNO). These
pins can be used for both digital input (like telling if a button is pushed) and digital output (like
powering an LED).
• PWM (8): You may have noticed the tilde (~) next to some of the digital pins (3, 5, 6, 9, 10,
and 11 on the UNO). These pins act as normal digital pins, but can also be used for something
called Pulse-Width Modulation (PWM). We have a tutorial on PWM, but for now, think of
these pins as being able to simulate analog output (like fading an LED in and out).
• AREF (9): Stands for Analog Reference. Most of the time you can leave this pin alone. It is
sometimes used to set an external reference voltage (between 0 and 5 Volts) as the upper limit
for the analog input pins.
Reset Button
Just like the original Nintendo, the Arduino has a reset button (10). Pushing it will temporarily connect
the reset pin to ground and restart any code that is loaded on the Arduino. This can be very useful if
your code doesn’t repeat, but you want to test it multiple times. Unlike the original Nintendo however,
blowing on the Arduino doesn't usually fix any problems.
Power LED Indicator
Just beneath and to the right of the word “UNO” on your circuit board, there’s a tiny LED next to the
word ‘ON’ (11). This LED should light up whenever you plug your Arduino into a power source. If this
light doesn’t turn on, there’s a good chance something is wrong. Time to re-check your circuit!
TX RX LEDs
TX is short for transmit, RX is short for receive. These markings appear quite a bit in electronics to
indicate the pins responsible for serial communication. In our case, there are two places on the Arduino
UNO where TX and RX appear -- once by digital pins 0 and 1, and a second time next to the TX and
RX indicator LEDs (12). These LEDs will give us some nice visual indications whenever our Arduino
is receiving or transmitting data (like when we’re loading a new program onto the board).
Main IC
The black thing with all the metal legs is an IC, or Integrated Circuit (13). Think of it as the brains of
our Arduino. The main IC on the Arduino is slightly different from board type to board type, but is
usually from the AT mega line of IC’s from the ATMEL company. This can be important, as you may
need to know the IC type (along with your board type) before loading up a new program from the
Arduino software. This information can usually be found in writing on the top side of the IC. If you
want to know more about the difference between various IC's, reading the datasheets is often a good
idea.
Voltage Regulator
The voltage regulator (14) is not actually something you can (or should) interact with on the Arduino.
But it is potentially useful to know that it is there and what it’s for. The voltage regulator does exactly
what it says -- it controls the amount of voltage that is let into the Arduino board. Think of it as a kind
of gatekeeper; it will turn away an extra voltage that might harm the circuit. Of course, it has its limits,
so don’t hook up your Arduino to anything greater than 20 volts.
