Arduino is a small-sized microcontroller board with supplementary components that has been designed to facilitate the use of a microcontroller in control projects. The basic board, Arduino UNO Revision 3, uses the 8-bit Atmel microcontroller, ATmega328P.
The board has a universal serial bus (USB) plug to enable it to be directly connected to a computer and a number of connection sockets to enable it to be connected to external items such as motors, relays, etc. The board can be powered by connection to an external power supply such as 9 V battery, or through the USB connection from the computer.
Pre-programmed into the on-board microcontroller chip is a bootloader that directly allows the uploading of programs into the microcontroller memory. The basic boards are supplemented by accessory boards, referred to as shield boards, such as an LCD display board, a motor board, and an Ethernet board, that can be plugged on top of the basic Arduino board and into board pin headers. Multiple shields can be stacked. By default, all Arduino pins are set for inputs. If outputs are needed, then the pins require to be configured.
The board is open source. This implies that anyone is permitted to make Arduino-compatible boards. Starter kits are available, typically including items like the Arduino board, a USB cable so that the board can be programmed from a computer, a breadboard to use for assembly of an external circuit with wires and commonly used components such as resistors, photoresistors, potentiometers, capacitors, push-buttons, temperature sensors, LCD alphanumeric display, LEDs, dc motor, H-bridge motor drive, optocouplers, transistors, and diodes.
The figure below demonstrates the basic elements of the Arduino UNO Revision 3 board:
Contents
Analogue Inputs
These are labelled A0 to A5 and can be used to detect voltage signals.
Digital Connections
Labelled Digital 0 to 13, these can be used for either inputs or outputs. The first two of these connections are also labelled RX and TX for receive and transmit respectively in communication.
USB connector
This is used to connect the board to a computer.
Serial Programming Connector
This offers a way of programming the Arduino without using the USB port.
LEDs
The board is equipped with three LEDs: one to indicate serial transmission (TX), one to indicate reception (RX) and one extra LED for use in projects.
Power supply connector
An external power supply can be connected to the board via a connector at the bottom left corner of the board. However, the board may be powered from the USB port during connection to a computer.
Microcontroller
The microcontroller ATmega328 comes pre-burned with a bootloader that allows a new program code to be uploaded to it without the use of an external hardware programmer.
Reset pin in the section power connectors
This resets the microcontroller so that it begins the program from the start. To perform a reset, this pin needs to be momentarily set low, that is, connected to 0 V. This action can also be initiated by using the reset switch.
Other pins in the power connectors
These can provide different voltages, that is, 3.5 V, 5 V, GND, and 9 V.
Arduino board, when purchased, has a sample program pre-installed. This program is to make an LED on the board flash. To start the program all you required to do is to supply power, which can be done by plugging into the USB port of a computer. The LED should then flash, so verifying that the board is working.
To install new software, referred to as sketches for Arduino boards, you need to install the Arduino software and load the USB drivers in your computer. Instructions on how to do this can be found on the Arduino website. Once this is done, you can upload a program to the Arduino board.
We have a range of Arduino boards available, in addition to the Arduino Uno board, which is the most standard board. The board is compatible with more shields (add-on boards) than other board models. The Uno’s main limitation is its ATmega328 chip, which does not have a lot of SRAM or flash memory, and this limits the kinds of program that can be loaded on the chip.
The Arduino Leonardo is a minor upgrade to the Uno and uses the ATmega32u4 chip. Its main advantage is the chip’s built-in USB compatibility that allows the Leonardo to interface with a PC.
The Arduino Due uses an Atmel SAM3X8E based on the ARM Cortex-M3 processor chip and this gives it 32-bit CPU, 84 MHz clock speed, 96 KB SRAM, 512 KB flash storage, with 54 digital I/O pins, 12 analogue input pins, 2 analog output pins and a USB port. The Arduino Due is primarily for more complicated projects that can make use of its more powerful processor, or that need more I/O pins than what is found on the smaller Arduino boards.
Other boards include the Arduino Mega 2560 which is based on the ATmega2560 chip, a high performance 8-bit microcontroller, and the Arduino Zero based on the Atmel 32-bit microcontroller SAMD21, featuring a 32-bit ARM cortex M0 processor core. We also have a range of configuration boards, that include, the Arduino Robot, which is Arduino on wheels. The robot is equipped with two processors, one for each of its two boards. The motor board drives the motors on the two drive wheels, while the control board reads sensors and determines how the robot is to operate.
You may also read:
- Software Development Tools for a Microcontroller Programmer
- How to Create a PIC Project using MPLAB X IDE
- The Basic Structure of Intel 8051 Microcontroller
