18 KiB

Raw Blame History

UnPacked / Unlondon

\begin{center} {\huge Enabling Exploration, Creativity, and Excellence In Art+Make+Tech} \end{center}

Challenging and embracing ideas related to new technologies and social platforms through the education, entertainment and engagement of our membership and the community-at-large.

121Studios: Coworking for Creatives
STEAM Outreach & Education
ExplodeConf
Nuit Blanche

Shawn: Day Job

Embedded Systems Designer, Monadnock Systems

Indoor location tracking w/ Bluetooth
Keychain / Fitness Band Widgets
Joystick for VR
Remote Controls
Internet of S*#t

Shawn: The Fun Stuff

Hacker, Church of the Weird Machine, Odd Duck

\begin{columns}[c] \column{0.50\textwidth}

\begin{itemize} \item Arduino compatible implant \item EEG Games / Toy Hacking \item Brain Stimulation \item Be Weird, Make Weird, Have Fun! \end{itemize}

\column{0.50\textwidth} \begin{center} \includegraphics[width=0.95\textwidth]{images/timbo.jpg} \vspace{5mm} \includegraphics[width=0.95\textwidth]{images/circadia.jpg} \end{center} \end{columns}

Titus: Day Job

Executive Director, UnPacked

121Studios
St. Thomas STEM Centre
&c

Titus: The Fun Stuff

Thinker, Jack of all Trades

What's in your kit?

Kit Contents

###Arduino Uno R3

###Solderless Breadboard

###Connecting wires

###Sensors

Temperature / Humidity
Light Sensor

What is Arduino?

It's a kit (on a board) with the bare minimum components to easily use the $\mu$C hardware. They do the basic, boring design needed for any board, so users only need to add the neat stuff.

Arduino Software

The Arduino folks also adapted an Integrated Development Environment (IDE) to their boards. This IDE allows us to easily write programs for their boards and then write the programs to the $\mu$C.

\Large Get the Arduino IDE: https://www.arduino.cc/en/Main/Software

Circuit Basics

Current

Current is the flow of charge through a circuit. Measured in Amperes (\si{\ampere}).

Resistance / Impedance

Circuits have a resistance to current flow that depends on the parts in the circuit.

Measured in Ohms (\si{\ohm})

Voltage

Voltage is a potential (akin to a pressure) pushing the current through a circuit. Current is said to flow from higher (+) voltage to lower (-) voltage.

Measured in Volts (\si{\volt})

Ohm's Law; Light

Voltage, Current and Resistance are related to each other.

As voltage increases, current increases
As voltage decreases, current decreases
As resistance increases, current decreases
As resistance decreases, current increases

\si{\volt}, \si{\ohm}, \si{\ampere}: The Water Analogy

If charge were water, then:

resistance = obstacles blocking flow
current = flow rate
voltage = change in height or pressure.

Diode

\begin{columns}[c] \column{0.50\textwidth}

\begin{itemize} \item One way value for current\footnotemark[1] \item LED \equiv Light Emitting Diode \item Band marks (-)\footnotemark[2] \item Longer leg marks (+) \end{itemize}

\column{0.50\textwidth} \begin{center} \includegraphics[width=0.75\textwidth]{images/diode.png} \vspace{5mm} \includegraphics[width=0.50\textwidth]{images/led.jpg} \end{center} \end{columns}

\footnotetext[1]{\tiny \url{https://learn.sparkfun.com/tutorials/diodes}} \footnotetext[2]{\tiny \url{https://learn.sparkfun.com/tutorials/polarity/diode-and-led-polarity}}

Diode Problems

Diodes don't limit current
Diodes aren't perfect (some current turned to heat)
Too much current \rightarrow Too much heat \rightarrow

\center{ \huge{\emph{What's that smell?} } }

Resistor

\begin{columns}[c] \column{0.50\textwidth}

\begin{itemize} \item \emph{Resists}/limits the flow of current \item Needed for LEDs: \approx\SI{1000}{\ohm}\ \item Button Pull-up/down: \ge\SI{10}{\kilo\ohm} \item Color coded, Google it \end{itemize} \column{0.50\textwidth}

\includegraphics[width=0.98\textwidth]{images/resistor.png}

\end{columns}

Buttons

Buttons connect or disconnect two wires/parts
Momentary Switch: Normally Closed (NC), Normally Open (NO)
Toggle Switch

Circuits

A circuit is a completed loop from HIGH potential (voltage) to LOW, which causes current to flow through some other components along the way.

Transducers

Often these other components are transducers, which convert electrical energy into another sort of energy:


Speaker	Electrical `\rightarrow` Sound
Microphone	Sound `\rightarrow` Electrical
LED	Electrical `\rightarrow` Light
LED	Light `\rightarrow` Electrical
Piezoelectric	Electrical `\rightarrow` Motion

Power

The power supply provides the energy to drive the system.

Can be a:

Voltage Regulator (converts one potential to another)
Batteries
Solar Panel

In our circuits, your laptop is converting it's power source to \SI{5}{\volt} and delivering power to our circuit via USB.

$\mu$Controller

Microcontroller ($\mu$C) is a processor, memory and a few peripherals on a standalone chip.

Processor: is a group of transistors that understands a dozen or so commands (ADD, SUB, JUMP..)
Memory: a circuit that can hold values.
Peripherals: Vary chip to chip, but often include timers, communications and ADC, DAC.

Seems complicated, but really simple. They read a command from the start of memory, then execute the command. At the end of the command, read the next command from the next memory cell and repeat^[some commands change the address of the next fetched command]

Digital Signals

Vcc: The power supply of the circuit elements
GND: The reference voltage (usually \SI{0}{\volt})
Connecting a part to Vcc = Logical 1 or High
Connecting to GND = Logical 0 or Low
Connecting various pins to Vcc or Ground is all the $\mu$C can do to talk to the world ¹

$\mu$Controller INPUT and OUTPUT

Most of the pins on the Arduino can be set for INPUT or OUTPUT mode.

INPUT mode pins listen for a signal (0 or 1) from another device
OUTPUT mode pins drive the pin High or Low

Floating Pins

What's happens if an INPUT mode pin tries to read the value of a pin that is connected to nothing? Is that a 1 or 0?

\center{\huge {No one knows!}}

It's dependant of transient charges, static, nearby electric fields, the phase of the moon, \ldots Whenever you want to check a digital signal, make sure that something is driving it (ensuring Vcc or GND).

$\mu$C + Digital Signals as Switches

If one end of an LED is connected to ground, and the other end is connected to an OUTPUT pin on a $\mu$Controller, then:

If the \mu$C sets the pin High (Vcc, \SI{5}{\volt}$) then current will flow from the pin through the LED and turn it on.
If \mu$C sets the pin Low (GND, \SI{0}{\volt}$) then the current will not flow and the LED is off.

Let's start programming

Configure Arduino

\begin{center} \includegraphics[width=0.98\textwidth]{images/arduino-board.png} \end{center}

Board: Arduino/Genuino UNO
Port: \ldots

The Code Environment

\begin{center} \includegraphics[width=0.95\textwidth]{images/arduino-toolbar.png} \end{center}

Your first Program

#define LED 13

/* the setup function runs once on reset / power */
void setup() {
  pinMode(LED, OUTPUT);
}

/* loop() repeats until reset or power off */
void loop() {
  digitalWrite(LED, HIGH);   // turn on LED
  delay(1000);              // wait for a second
  digitalWrite(LED, LOW);    // turn the off LED
  delay(1000);
}

Add Some Parts

Breadboard

Connectors gently pinch component leads, wires.
Have internal connections

Power Up the Rails

We use the long rows to distribute power. The Arduino outputs \SI{5}{\volt} on the pin marked 5V, the reference (GND) is marked GND.

Buzzer & Button: Hardware

\begin{center} \includegraphics[width=0.98\textwidth]{images/buzzer-breadboard.png} \end{center}

Push Button: Zoom

\begin{center} \includegraphics[width=0.98\textwidth]{images/bb+switch+zoom.png} \end{center}

Pullup / Pulldown Resistors

Reading a floating pin is bad. A switch only connects and disconnects a wire. When the wire is disconnected... the INPUT pin is floating!

\vfill

Solution:

Connect the pin to Vcc so that it reads High; use a resistor to prevent short circuit (limit current).

Buzzer: Zoom

\begin{center} \includegraphics[width=0.98\textwidth]{images/buzzer-zoom.png} \end{center}

Buzzer / Button: Software (Part 1)

#define BUTTON 2
#define BUZZER 8

int button_state;

void setup() {
  pinMode(BUTTON, INPUT);
  pinMode(BUZZER, OUTPUT);
  digitalWrite(BUZZER, LOW); /* Start w/ LED off */
}

Programming Note: Variables

Declare a variable:

int button_state = HIGH;

<type> <name> [= <initial value>]; (value optional)

It's a name, like a preprocessor #define, but the value can change at runtime

Programming Note: If Statement

if (condition) {
	// body: Runs if condition true ( != 0)
} else {
	// Runs if condition false ( == 0 )
}

body code inside curly braces: { }
condition evaluates to 0 \rightarrow body code skipped
else section is optional, runs if condition evaluates to 0
condition evaluates to not 0 \rightarrow body code runs

Programming Note: `==`

In C-like languages, the == operator checks if two things (statements, variables, \ldots) are equal to each other.

It returns 1 if the items are equal, or
It returns 0 if the items are not equal

Programming Note: Functions

Functions make it easy to reuse code. You already know / use several functions:

pinMode
digitalWrite
delay

digitalRead(pin number) returns HIGH or LOW depending on current state of any INPUT pin.

You can write your own functions!

Programming Note: Writing Functions

void my_function(int arg1, ...) {
	// Do fun things
}

void:: Return type. Void means nothing returned. Can be any type.
my_function:: A name for your function
arguments:: A type and name for any parameters you want to use in your function from the outside.

Define a function once, you can use it again and again. Better than copy/pasting.

Push Button: Software (Part 2)

void buzz(int ms) {
	digitalWrite(BUZZER, HIGH);
	delay(ms);
	digitalWrite(BUZZER, LOW);
}
void loop() {
  button_state = digitalRead(BUTTON);
  if (button_state == LOW) {
	buzz(100);
  }
}

More Parts

Potentiometer

Puh - ten - she - ometer

Pot for short
A Voltage Divider
Voltage at Wiper is somewhere between potential at the two terminals.
The exact wiper potential depends on the position of the knob/lever.

ADC: Analog to Digital Converter

A peripheral of the $\mu$Controller
Measures Potential, outputs a number
In our case, \SI{0}{\volt}\rightarrow0 and \SI{5}{\volt}\rightarrow1023
A0-A5 pins on Arduino can be used
Fun uses: Reading pot position, sampling audio, reading from sensors

The Pot Hookup

\begin{center} \includegraphics[width=0.98\textwidth]{images/bb+switch+pot.png} \end{center}

Connect center pin to A0, outer pins to (+) and (-) rails

Pot Code

analogRead(pin) returns the voltage at the pin (0--1023), it can be used directly or via variable.

#define LED 13
void setup() {
  pinMode(LED, OUTPUT);
}
void loop() {
  digitalWrite(LED, HIGH);
  delay(analogRead(A0));
  digitalWrite(LED, LOW);
  delay(analogRead(A0));
}

Since the delay() calls use the result of analogRead (0-1023), the blink rate changes with knob position.

Shall we play a game?

Hooking up a bunch of LEDs

\begin{center} \includegraphics[width=0.65\textwidth]{images/bb+switch+pot+leds.png} \end{center}

LEDs, the first one

Looks complicated, but for each LED: The short leg goes to ground, the long leg goes to one end of a resistor, and the other end of the resistor goes to the arduino pin.

\begin{center} \includegraphics[width=0.55\textwidth]{images/one-led.png} \end{center}

Programming Note: `for` Loop

for ( initializer ; condition; increment ) {
	// This body will repeat while condition != 0
}

initializer: Executed once at beginning of loop. Often used to declare a local variable.
condition: Loop will repeat while condition is true (\neq0)
increment: Runs after each loop. Often used to increment variables.

\center{All fields are optional}

Cylon Simulator: Part. 1; Pin Setup

int delay_ms;
void setup() {
	pinMode(3, OUTPUT);
	pinMode(4, OUTPUT);
	pinMode(5, OUTPUT);
	pinMode(6, OUTPUT);
	pinMode(7, OUTPUT);
}

Cylon Simulator: Part. 2

void loop () {
	for (int i = 4; i <= 7; i++) {
		delay_ms = analogRead(A0);
		digitalWrite(i - 1, LOW);
		digitalWrite(i, HIGH);
		delay(delay_ms);
	}
	for (int i = 6; i >= 3; i--) {
		delay_ms = analogRead(A0);
		digitalWrite(i + 1, LOW);
		digitalWrite(i, HIGH);
		delay(delay_ms);
	}
}

Programming Note: `while` Loop

while ( statement ) {
	// This body will repeat while condition is true
	// True means statement != 0
}

initializer: Executed once at beginning of loop. Often used to declare a local variable.
condition: Loop will repeat while condition is true (\neq0)
increment: Runs after each loop. Often used to increment variables.

\center{All fields are optional}

Winner, Winner, Chicken Dinner

#define WINNER 5
void check_delay(int cur_led, int delay_ms) {
  unsigned long start = millis();
  while (millis() < start+delay_ms) {
    if (digitalRead(BUTTON) == LOW) {
      if (cur_led == WINNER) {
        do_winner();
      } else {
        while (digitalRead(BUTTON) == LOW) {
          do_loser();
        }
      }
    }
  }
}

More functions, pt. 1

void set_all_leds(int state) {
  for (int i = 3; i <= 7; i++) {
    digitalWrite(i, state);
  }
}

void do_loser(void) {
  buzz(500);
}

More functions, pt. 2

void do_winner(void) {
  set_all_leds(HIGH);
  buzz(100);
  delay(100);
  buzz(100);
  set_all_leds(LOW);
}

Putting it Together

loop () {
	for (int i = 4; i <= 7; i++) {
		delay_ms = analogRead(A0);
		digitalWrite(i - 1, LOW);
		digitalWrite(i, HIGH);
		check_delay(i, delay_ms);
	}
	for (int i = 6; i >= 3; i--) {
		...
		check_delay(i, delay_ms);
	}
}

The End?

Extra Credit

Ohm's Law

Ohm's Law relates current to potential and resistance.

 V = IR

 I=\frac{V}{R}

 R = \frac{V}{I}

V = Potential in Volts (\si{\volt})
I = Current in Amperes (\si{\ampere})
R = Resistance in Ohms (\si{\ohm})

Ohm's Law: Example

The datasheet for an LED says that the maximum continuous current is \SI{15}{\milli\ampere}. Your circuit operates at \SI{5}{\volt}\footnotemark[1]. How big should your resistor be?

 \si{\ohm} = \frac{\SI{5}{\volt}}{\SI{0.015}{\ampere}} = 333.\overline{3}\si{\ohm}

How much current for our cheet sheet value?

 \si{\ampere} = \frac{\SI{5}{\volt}}{\SI{1}{\kilo\ohm}} = \SI{5}{\milli\ampere}

\footnotetext[1]{\tiny Actually, this calculation is inaccurate. LEDs will have a forward voltage drop of between \SI{1.8}{\volt} and \SI{3.3}{\volt} this should be subtracted from \si{\volt} above... but it's not critical.}

Current Limits, Arduino

No single pin should source more that \SI{20}{\milli\ampere} (\SI{40}{\milli\ampere} is absolute max)
Pins are ganged together in groups of 8, no group should source more than \SI{150}{\milli\ampere} total
The whole board cannot source more than \SI{200}{\milli\ampere} total

Practically speaking, this means that the Arduino cannot drive speakers, most motors, or anything normally mains powered.

So\ldots no Arduino smart blender?

You can control almost anything with an arduino, you just can't power it with the Arduino. There are various devices that let you switch highier powered devices:

Transistors
Relays
Solid State Relays
Triac

HIGHs and LOWs

Many different logic levels are in common use: \SI{1.2}{\volt}, \SI{1.8}{\volt}, \SI{2.5}{\volt}, \SI{3.3}{\volt}, and \SI{5}{\volt}. The voltage cited is the nominal Vcc of the system.

A HIGH signal is generally any voltage \geq \frac{2}{3}V_{cc}.

A LOW signal is generally any voltage \leq \frac{1}{3}V_{cc}.

HIGHs and LOWs, pt. 2

In your travels, you're likely to see both \SI{5}{\volt} and \SI{3.3}{\volt} sensors and peripherals.

Since \SI{3.3}{\volt}\geq\frac{2}{3}V_cc your Arduino will accept input from a \SI{3.3}{\volt} peripheral without issue.

If you drive an output to \SI{5}{\volt} while it's connected to a \SI{3.3}{\volt} peripheral with an Arduino it will blow up your peripheral.^[In the datasheet for the sensor, it'll have a section called Absolute Maximums. Generally \SI{3.3}{\volt} parts won't accept more that \approx\SI{3.6}{\volt}, but some will.]

HIGHs and LOWs, pt. 3

Solutions:

Level Shifter: A dedicated chip that translates between voltages. Available as uni or bidirectional.
Buy a 3.3V Arduino Compatible. Arduinos are available that operate at the lower voltage.

w/o fancy peripherals or dirty tricks ↩︎

18 KiB Raw Blame History

UnPacked / Unlondon

Shawn: Day Job

Shawn: The Fun Stuff

Titus: Day Job

Titus: The Fun Stuff

What's in your kit?

Kit Contents

What is Arduino?

Arduino Software

Circuit Basics

Current

Resistance / Impedance

Voltage

Ohm's Law; Light

\si{\volt}, \si{\ohm}, \si{\ampere}: The Water Analogy

Diode

Diode Problems

Resistor

Buttons

Circuits

Transducers

Power

$\mu$Controller

Digital Signals

$\mu$Controller INPUT and OUTPUT

Floating Pins

$\mu$C + Digital Signals as Switches

Let's start programming

Configure Arduino

The Code Environment

Your first Program

Add Some Parts

Breadboard

Power Up the Rails

Buzzer & Button: Hardware

Push Button: Zoom

Pullup / Pulldown Resistors

Buzzer: Zoom

Buzzer / Button: Software (Part 1)

Programming Note: Variables

Programming Note: If Statement

Programming Note: ==

Programming Note: Functions

Programming Note: Writing Functions

Push Button: Software (Part 2)

More Parts

Potentiometer

ADC: Analog to Digital Converter

The Pot Hookup

Pot Code

Shall we play a game?

Hooking up a bunch of LEDs

LEDs, the first one

Programming Note: for Loop

Cylon Simulator: Part. 1; Pin Setup

Cylon Simulator: Part. 2

Programming Note: while Loop

Winner, Winner, Chicken Dinner

More functions, pt. 1

More functions, pt. 2

Putting it Together

The End?

Extra Credit

Ohm's Law

Ohm's Law: Example

Current Limits, Arduino

So\ldots no Arduino smart blender?

HIGHs and LOWs

HIGHs and LOWs, pt. 2

HIGHs and LOWs, pt. 3

18 KiB

Raw Blame History

Programming Note: `==`

Programming Note: `for` Loop

Programming Note: `while` Loop