Arduino 101
Introduction to Microprocessors

Nick Borko

September 21, 2013

Except where otherwise noted, this work is licensed under
http://creativecommons.org/licenses/by-nc-sa/3.0

Agenda

• Introduction
• What is a microprocessor?
• What's so great about the Arduino?
  • History of the Arduino
  • Overview of the Arduino hardware
  • Overview of the Arduino IDE
  • Overview of Arduino programming
• Hands on: Oooh, Blinky!

What is a Microprocessor?

There are 5 basic functions units of a computer system:

• Control Unit (CU)
• Arithmetic-Logical-Unit (ALU)
• Memory (ROM, RAM, Registers)
• Input
• Output

What is a Microprocessor?

What is a Microprocessor?

• The classical definition of a microprocessor is the combination of the Control Unit, Arithmetical-Logical-Unit and Registers in a single package, a.k.a. CPU
• Modern microprocessors also integrate input and output ports and on-chip memory (cache, EEPROM, flash, RAM)
• The Arduino is controlled by a microprocessor called the AVR

General Microprocessor
Architecture (8080, 6502)

Atmel AVR Architecture

What's so great about the Arduino?

Arduino isn't just hardware, it's a complete development environment:

• An open-source electronics prototyping platform based on inexpensive hardware
• A free, easy to use software integrated development environment (IDE)
• A familiar programming language based on Processing and C/C++
• An active, diverse, inclusive development community

History of the Arduino

• Developed by Massimo Banzi and David Cuartielles at the Interaction Design Institute Ivrea, Italy in 2005
  • Designed to be an inexpensive prototyping system for student interactive design projects
  • Built upon the Wiring Platform, by Hernando Barragán, based on the AVR and Processing
• See the full length documentary video at http://vimeo.com/18539129

Arduino Hardware Overview

• Based on the Atmel Atmega168/328[P], an 8-bit AVR running on 5V at 16MHz
• Programmed with a bootloader to bootstrap loading programs from USB
• Microprocessor pins are broken out to headers in a standard configuration
• Additional "shield" boards can be "stacked" on the headers for extended functionality

Arduino UNO R3 (~$30)

Arduino IDE Overview

• The Arduino IDE (Integrated Development Environment) is all you need to develop programs for the Arduino
• Written in Java, based on the Wiring IDE
• Runs on Windows, OSX and Linux
• Automates the entire AVR development toolchain: editor, compiler/linker (avrgcc), uploader (avrdude), terminal emulator, and more

Arduino IDE (1.0.5)

Arduino Programming Overview

• The Arduino programming language is actually C++, written on top of the Arduino Core
• A programmer doesn't have to know how to write C++ programs, only the conventions for writing Arduino programs
• The Arduino IDE takes care of compiling, linking and uploading the program, so you don't have to know how to use any of those tools

What is the Arduino Core?

• The Arduino Core provides the main entry function, data types, and high level functions to program the AVR
• It is a library that abstracts low level microprocessor programming concepts into high level function calls
• It is based on Processing, a language designed to teach programming in a visual context to non-programmers

What is the Arduino Core?

• The Arduino Core assigns a set of standard numbers to the generic I/O pins of the microprocessor for use in programs
• The Arduino Core is automatically included in and linked to your Arduino programs
• You can extend the Arduino Core with regular C and C++ libraries

What is the Arduino Core?

// http://hackaday.com/2010/10/25/avr-programming-02-the-hardware/
#include <avr/io.h>
#include <avr/interrupt.h>

int main(void) {
  //Setup the clock
  cli();               //Disable global interrupts
  TCCR1B |= 1<<CS11 | 1<<CS10; //Divide by 64
  OCR1A = 15624;       //Count 15624 cycles for 1 second interrupt
  TCCR1B |= 1<<WGM12;  //Put Timer/Counter1 in CTC mode
  TIMSK1 |= 1<<OCIE1A; //enable timer compare interrupt
  sei();               //Enable global interrupts

  DDRD |= (1<<0);      //Set PortD Pin0 as an output
  PORTD |= (1<<0);     //Set PortD Pin0 high to turn on LED

  while(1) { }         //Loop forever, interrupts do the rest
}

//Interrupt Service Routine
ISR(TIMER1_COMPA_vect) {
  PORTD ^= (1<<0);     //Use xor to toggle the LED
}

What is the Arduino Core?

void setup() {
  // initialize the digital pin as an output.
  // Pin 13 has an LED connected on most Arduino boards:
  pinMode(13, OUTPUT);
}
void loop() {
  digitalWrite(13, HIGH); // set the LED on
  delay(1000);            // wait for a second
  digitalWrite(13, LOW);  // set the LED off
  delay(1000);            // wait for a second
}

Advantages of the Arduino Core

• You don't have to write boilerplate code usually required for microprocessor programming
• Interaction with microprocessor functions is done through high level function calls rather than looking up bits to set in registers from a data sheet
• Code is readable and understandable by humans, even by non-programmers

Hands On: Blink a LED

• Build an LED circuit on your breadboard to blink using the Arduino
• Connect the circuit to the headers on the Arduino board
• Upload the "Blink" example sketch from the Arduino IDE

Sample LED Circuit Layout

• 1 Red LED
• 1 220Ω Resistor

Connecting to the Arduino

Loading the Blink Sketch

Upoading the Blink Sketch

Conclusion

• What is a microprocessor?
• What's so great about the Arduino?
  • History of the Arduino
  • Overview of the Arduino hardware
  • Overview of the Arduino IDE
  • Overview of Arduino programming
• Hands on: Oooh, Blinky!
• Next Steps: Basic Circuit Theory

This presentation is available online at:
http://nborko.github.io/arduino101/

All source files used for this workshop are available online at:
https://github.com/nborko/arduino101