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Developing Software for Open
Source Hardware
© Prof. Dr. Michael Stal, 2014
Engineers never fail
I have not failed. I've
just found 10,000
ways that won't
work.
[Thomas A. Edison]
The Rise of Physical Computing
Definition: Building interactive
physical systems by the use of
software and hardware that ...
Maker Movement
Modern version of DIY (DoIt-Yourself)
extends the idea of open
source software
build things with free
hardw...
Portals with Public Domain Projects
Examples
Thingiverse
http://www.thingiverse.com
Instructables
http://www.instructables...
Instructions and Design Documents
Includes
Design CAD files
Part list
Instructions how to
assemble the parts
Useful Things – well, not always that useful
Design provided as STL
(Standard Triangulation
Format) documents in
verbose A...
Production of 3D Objects
How?
Either yourself using a 3D
printer (from under 1000
€ to 10.000s of €)
Or by cheap commercia...
So, What?
Increasing number of open
source microcontroller
boards
Excellent and cheap tools for
prototyping
Useful to lear...
Intel goes Arduino
Even large companies support Arduino:
headline on October, 3rd, 2013:
Intel launches Galileo, an Arduin...
Open Source Hardware Boards
The most important ones:
Arduino
(microcontroller board)
Raspberry Pi (controller
plus a Linux...
Prerequisites
Which prerequisites are necessary for building
such systems?

Small Systems, Medium Systems with
Low Complex...
Arduino & Friends

HAL (powered by Arduino)
Back to the Future
2005: Started as project at the
Interaction Design Institute
Ivrea, Italy
2006: Won a price at Prix Ars...
The Arduino Family
Arduino comes in a lot of
flavors, e.g.,
LilyPad Arduino (Arduino for
your clothes)
Arduino Uno Rev. 3 ...
Arduino Board Design
Analog
Reference
USB Used to load
programs
(=sketches) to the
board, to power the
board, and for seri...
I2C* – The Low-Speed Bus
LowMulti-master serial single-ended
computer bus invented by
Philips Semiconductors
Used in most ...
Processors
Newer boards (Due): ARM
with Cortex-M3 (32 Bit
Architecture)
Previous Boards (Uno, Mega.
Leonardo, Duemillenova...
Solderless Breadboards
Connecting the Arduino to a
breadboard is very useful for
designing circuits without
soldering
When...
Standard Components
You‘ll need a basic set of
components:

WRONG

Resistors, Potis, Capacitors
Transistors, Diodes, LEDs
...
Sensor & Actuator Components
Pressure Sensor

Ultrasonic

Gyro

Hall Sensor
Temperature Sensor

Developers needs to add sp...
Shields, Shields, Shields
Arduino shields (incl. program
libraries) add advanced logic
Built to fit on top of an
Arduino b...
Circuit Design with Fritzing
Fritzing, an open
source editor for
circuit design
developed by
University of
Applied Science...
Programming an Arduino
When coding a sketch (=
program) for microcontroller
boards like Arduino, two steps
are necessary:
...
The Arduino IDE*
Available for MacOS X,
Windows, Linux at no cost
Based on Processing, built with
Java
Subset of C/C++,
(i...
„Hello World“
I respect the old
tradition and
present the
embedded cousine
of „Hello, World“...
... which results in a
bli...
Programming Models

generate

In general, there are three
programming models for
embedded devices:

Arduino IDE based on c...
Reactor Pattern
If the event-driven model is not supported, you may use the
Reactor pattern to avoid the command-driven mo...
Recommended Design Approach
In most projects, finite state machines (FSM) (together with timing
diagrams) are the best cho...
Host/Target Development
Host

Target
USB

Test Environment
IDE

Bootloader
starts on reset

Command
Line
ICSB port for pro...
Developer Ecosystems
Arduino native IDE
MariaMole: alternative IDE
CodeBlocks for AVR &
Arduino
Arduino for Microsoft
Visu...
Java VM on Arduino
HaikoVM runs on Arduino and
implements Java 6 bytecode
Runs on AVR ATmega8, AVR
ATmega328p (and Windows...
Learning by Example
Examples are helpful to
introduce Arduino concepts
Thanks to Mike McRoberts for
providing a free manua...
Arduino Projects
I will demo one of my own
experiments
The other projects are
actually taken from the
Arduino Playground:
...
Project Traffic Light
Building a Traffic Light with LEDs and a Piezo speaker that signals
red or green.
Example 1: Debouncing
Problem: when pressing a
switch or button the signal
can bounce for a while
Solution: Debouncing pat...
Example 1 – Code (Setup)
// constants won't change. They're used here to set pin numbers:
const int buttonPin = 2;
// the ...
Example 1 – Code (Loop)
void loop() {
// read the state of the switch into a local variable:
int reading = digitalRead(but...
Alternative Solution
Using the Debounce Library (DRY)
Available in the Arduino IDE
Implements the same functionality in an...
Example 2: Pull-Up Resistors
PullProblem: circuits are
subject to electrical
fluctuations which may lead
to an undefined s...
Example 2 – Code
void setup(){
Serial.begin(9600); // start serial connection
pinMode(2, INPUT_PULLUP); // pin 2 is input ...
Example 3: Using PWM
Problem: for dimming a
led, ..., we need to change
the actual current
continuously, but how?
Solution...
Example 3 – Code
int ledPin = 9;

// LED connected to digital pin 9

void setup() {
// nothing happens in setup
}
void loo...
Example 4: Using Libraries
Problem: How can we
access the LiquidChrystal
display
Solution: we need to
import the LiquidChr...
Example 4 – Code
#include <LiquidCrystal.h> // the library for using LCDs
// initialize the library with the numbers of th...
Example 5: Control Speed of DC
Motor
Problem: Connecting a
low current Arduino with a
high current consumer
Solution:
Tran...
Example 5 – Code
int
int
int
int

potPin = A0; // potentiometer on analog pin A0
motorPin = 9; // motor on digital pin 9
p...
Alternative Solution
Use a motor shield (several available)
Can support multiple motors (brushed dc motor, stepper, servo)...
Alternative – Code (Setup)
const int
PWM_A
=
DIR_A
=
BRAKE_A =
SNS_A
=

3,
12,
9,
A0;

void setup() {
// Configure the A o...
Alternative – Code (Loop 1)
void loop() {
// Set the outputs to run the motor forward
digitalWrite(BRAKE_A, LOW);
digitalW...
Alternative – Code (Loop 2)
// … continued
// Set the outputs to run the motor backward
Serial.println("Backward");
digita...
Example 6: Interface to Processing
Problem: How can we
access Arduino from
Processing?
Solution: use the
Processing librar...
Example 6 – Code
import processing.serial.*;
import cc.arduino.*;
Arduino arduino;
int ledPin = 13;
void setup()
{
//print...
Libraries
If you want to provide a library you need to program in C/C++
Interface defined in header file, implementation i...
Arduino Simulators
Simulator for those with limited tinkering capabilities or without interest
Virtronics not perfect, but...
Netduino
„Arduino.NET“

Shield-compatible with Arduino Uno
Rev. 3
Based on .NET Micro Framework
Supports C#, VB, ...
STMic...
Blinking LED in Netduino
In Visual Studio:
Change deployment
target from emulator
to the real board (in
the „project menu“...
EventEvent-Driven Netduino
Event-driven system-level example using .NET eventhandlers

/* imports as in the Blinking LED e...
Raspberry Pi
more a cheap ARM6-based PC to go
with size of a credit card
With 1 GHz, 512 MB RAM, separate
Broadcom Graphic...
Using the GPIO Pins
Different choices:
Python, favourite
language of the RPi
creators
Unix Shell: writing 1 to
the port 17...
Expanding the Raspberry Pi
Limited capabilities compared with
Arduino
Various shields available, e.g.:
Shield to connect R...
beagleboard.org
beagleboard.org - BeagleBone
BeagleBone Black, the sprinter:
Powered by Embedded Linux
CPU AM335x 1GHz ARM...
BeagleBone External Interface Pins

Satisfaction guaranteed
BeagleBone Programming
Supports Python, Perl,
C/C++, JVM
Languages, JavaScript
+ BoneScript Library,
Shell commands, ...
C...
And the rest?
pcDuino: Arduino + Android
or Linux
Nanode: Actually, an extended
Arduino
Libelium Waspnode: Designed
for Wi...
What we didn‘t hear
This was the tip of the iceberg
In practice, we face additional
challenges:
Multitasking and Synchroni...
Robotics
For robotics applications you may
use Arduino, Raspberry Pi,
BeagleBone et al. but that is
tedious
Often, special...
State-of-theState-of-the-Art
Software is essential for
embedded devices
Only a few systems today aren‘t
based on software
...
Future Trends
The Future is Embedded
Modern cars contain a network
with several dozens
interconnected embedded
systems
In ...
Conclusions
Open source hardware boards offer a cheap and
easy way to dive into embedded systems
Arduino & Raspberry Pi & ...
Some folks won‘t ever give
away their Arduino board
Others would shamelessly
steal it
It is like a precious ring
So, keep ...
Last Words:The Pain of Engineering
The major difference
between a thing that
might go wrong and a
thing that cannot
possib...
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Transcript of "Oop 2014 embedded systems with open source hardware v2"

  1. 1. Developing Software for Open Source Hardware © Prof. Dr. Michael Stal, 2014
  2. 2. Engineers never fail I have not failed. I've just found 10,000 ways that won't work. [Thomas A. Edison]
  3. 3. The Rise of Physical Computing Definition: Building interactive physical systems by the use of software and hardware that can sense and respond to the analog world […] In practical use, the term most often describes handmade art, design or DIY hobby projects that use sensors and microcontrollers to translate analog input to a software system, Arduino-based Laser Harp: visit and/or control electro-mechanical http://makezine.com/projects/laserharp/ for detailed instructions devices such as motors, servos, lighting or other hardware.
  4. 4. Maker Movement Modern version of DIY (DoIt-Yourself) extends the idea of open source software build things with free hardware and donate the design to the community FabLabs* for tinkerers who share tools as opposed to owning them Increasing number of s * FabLab = Fabrication Laboratory
  5. 5. Portals with Public Domain Projects Examples Thingiverse http://www.thingiverse.com Instructables http://www.instructables.com
  6. 6. Instructions and Design Documents Includes Design CAD files Part list Instructions how to assemble the parts
  7. 7. Useful Things – well, not always that useful Design provided as STL (Standard Triangulation Format) documents in verbose ASCII or in compact binary format Example: solid name facet normal n1 n2 n3 outer loop vertex p1x p1y p1z vertex p2x p2y p2z vertex p3x p3y p3z endloop endfacet endsolid name
  8. 8. Production of 3D Objects How? Either yourself using a 3D printer (from under 1000 € to 10.000s of €) Or by cheap commercial fabrication companies (on-demand production) Main benefit: feasible even for small amounts of items Liability: may make piracy easier
  9. 9. So, What? Increasing number of open source microcontroller boards Excellent and cheap tools for prototyping Useful to learn basics of software development for embedded systems Scope are systems w/o stringent realtime/dependability requirements
  10. 10. Intel goes Arduino Even large companies support Arduino: headline on October, 3rd, 2013: Intel launches Galileo, an Arduino-compatible development board with x86 CPU
  11. 11. Open Source Hardware Boards The most important ones: Arduino (microcontroller board) Raspberry Pi (controller plus a Linux PC) NetDuino (layout compatible with Arduino but .NET based) BeagleBone (microcontroller board, Embedded Linux) Typical price range from 20€ to around 50€ Main focus of this talk
  12. 12. Prerequisites Which prerequisites are necessary for building such systems? Small Systems, Medium Systems with Low Complexity: For implementing existing designs, only basic knowledge of electronics/mechatronics Some rather inexpensive tools Sets like the Arduino Starter Kit Hint: many open source projects available in the Internet and in books Larger and/or complex systems: Knowledge about electrical engineering/mechatronics Soldering skills and Soldering station (except if only prototyping on breadboards) Electronic test instruments (oscilloscope, frequence analyzer, power generator, voltmeters...) A collection of components and ICs Tools, Cables, Breadboard, Hansaplast, ... David L. Jones publishes excellent videos on electronics in his blog: EEVBlog (Electronics Engineering Video Blog)
  13. 13. Arduino & Friends HAL (powered by Arduino)
  14. 14. Back to the Future 2005: Started as project at the Interaction Design Institute Ivrea, Italy 2006: Won a price at Prix Ars Electronica in 2006 Name taken from Arduino d'Ivrea (King of Italy around 1002 AC) * Goal: up-to-date board for students as an alternative to BASIC Stamp & Wiring framework „Processing for Hardware“ Creative Common License Watch documentary on http://vimeo.com/18539129 * well, that‘s the romantic version. Actually, it was named after a local pub Arduino Web Site http://arduino.cc Creators of Arduino with Massimo Banzi (to the right): First prototype board, made in 2005
  15. 15. The Arduino Family Arduino comes in a lot of flavors, e.g., LilyPad Arduino (Arduino for your clothes) Arduino Uno Rev. 3 (the „reference model“) Arduino Yun and Arduino Tre (microcontroller + separate Linux system on one board) Commercial companies sell their own implementations: e.g., SainSmart, Seed, AdaFruit BYO: You can even build your own Arduino board
  16. 16. Arduino Board Design Analog Reference USB Used to load programs (=sketches) to the board, to power the board, and for serial communication Digital Ground CPU with 16MHz Digital I/O Pins 2-13 (9, 10, 11with PWM = Pulse Width Modulation) Pins 1 & 2: Digital I/O. When used for communication then Serial In/Out, TX/RX Jumpers: Toggling between USB power and external power (jumpers) Boards (i.e., their pins) have a maximum current they can handle. Most Arduino boards define a maximum of 40 mA. Higher values will cause damage. In-Circuit Serial Programmer: if you need to upload another bootloader Reset Button: on reset the bootloader restarts External Power Supply Power Connectors connected with your board. Not all boards use 5V! Analog In: 0-5
  17. 17. I2C* – The Low-Speed Bus LowMulti-master serial single-ended computer bus invented by Philips Semiconductors Used in most open source hardware boards for attaching low-speed peripherals (speed 10 Kb/s-100Kb/s; newer versions even up to 3.6 Mb/s) Two bidirectional open-drain lines: Serial Data Line (SDA) und Serial Clock (SCL) Pull-up resistors to prevent data floating Wire library available (for accessing I2C) Master generates the clock and initiates communication Slave receives clock and responds when addressed by master Master sends only if it detects no start or stop bit sent by another master Single Message or Multi Message License free; only slave addresses must be bought * I2C = Inter-Integrated Circuit, invented by Philips Semiconductor Division, now NXP
  18. 18. Processors Newer boards (Due): ARM with Cortex-M3 (32 Bit Architecture) Previous Boards (Uno, Mega. Leonardo, Duemillenova, ...): based on Atmel‘s chip family ATMega xxx, 8 Bit Architecture A bridge connects both worlds Arduino Yun and Tre: additional but separate on-board unit (Atheros resp. ARM Cortex A8) running Linux (OpenWRT) Arduino Yun Architecture
  19. 19. Solderless Breadboards Connecting the Arduino to a breadboard is very useful for designing circuits without soldering When finished you may use a PCB (Printed Circuit Board) instead Breadboards consist of pin holes to place components (terminal strip) as well as bus strips: Terminal strip: all pin holes Bus strips for power supply (red = voltage, blue = ground) Notch in the middle (where mostly ICs such as DIPs are placed)
  20. 20. Standard Components You‘ll need a basic set of components: WRONG Resistors, Potis, Capacitors Transistors, Diodes, LEDs Buttons, Switches Relays,Transformators Motors Standard ICs such as OpAmps, L298 bridges App for looking up resistor color codes Wires, wires, wires A 9V block battery with a connector BETTER
  21. 21. Sensor & Actuator Components Pressure Sensor Ultrasonic Gyro Hall Sensor Temperature Sensor Developers needs to add specific code for reading or writing actuator/sensor values Usually attached through an analog port Specification of chip/component explains how to map between sensor values and physical units PWM (Pulse Width Modulation) often used in digital outputs to vary intensity of speed, volume, brightness, ...
  22. 22. Shields, Shields, Shields Arduino shields (incl. program libraries) add advanced logic Built to fit on top of an Arduino board Typically, provide the same pins like the Arduino (stacking of boards) Examples: Motor Shield (Arduino) LCD Shield (Sparkfun) Proto Shield (Seeed Studio) GPS Shield (Adafruit) WiFi Shield (AsyncLabs) See http://shieldlist.org/
  23. 23. Circuit Design with Fritzing Fritzing, an open source editor for circuit design developed by University of Applied Sciences, Potsdam Fritzing.org: nonprofit organization Supports, Mac OS X, Windows, Linux You can directly order a PCB board from within the editor
  24. 24. Programming an Arduino When coding a sketch (= program) for microcontroller boards like Arduino, two steps are necessary: Initialization Controlling & Monitoring 1. 2. Initialization phase executed once at start-up time: definitions and initialization of ports, connections, ... Controlling & Monitoring happens in an „endless“ loop. Sketch can monitor and control the board Application may terminate itself on specific events start Initialization Controlling & Monitoring exit
  25. 25. The Arduino IDE* Available for MacOS X, Windows, Linux at no cost Based on Processing, built with Java Subset of C/C++, (implementation of Wiring) Uses gcc & avr-gcc libraries in the build process C/C++ Libraries import You may use gcc directly or within Eclipse for C++ Other languages such as Java can remotely connect to Arduino using a wrapper on top of a RxTx native library * Free guide available at http://www.me.umn.edu/courses/me2011/arduino/arduinoGuide.pdf
  26. 26. „Hello World“ I respect the old tradition and present the embedded cousine of „Hello, World“... ... which results in a blinking LED Language based on C/C++ // Pin 13 has an LED connected on most boards int led = 13; // the setup routine - runs after each reset: void setup() { // initialize digital pin as an output pin pinMode(led, OUTPUT); Serial.begin(9600); // start serial port } // infinite loop; HIGH & LOW are voltage levels! void loop() { Serial.println(“Hello, World”); // send string digitalWrite(led, HIGH); // shine a light delay(1000); // wait for a second digitalWrite(led, LOW); // switch off LED delay(1000); // wait for a second } Serial stream received by host and displayed on the IDE‘s Serial Monitor if available
  27. 27. Programming Models generate In general, there are three programming models for embedded devices: Arduino IDE based on command-driven mode. Command-Driven (proactive, polling) +ü´ßw saeqq Event-Driven* (reactive, Pub/Sub) Model-Driven (e.g., Matlab + Simulink, Labview) Command Driven All of these models have strengths and limitations Select the right one for your environment Model-Driven generates code for one of the other models * It is also called Behaviour-driven or Reactive Model
  28. 28. Reactor Pattern If the event-driven model is not supported, you may use the Reactor pattern to avoid the command-driven model. dispatches * Reactor owns maintains select notifies * Event_ Handler * Consider whether you have timing constraints before use! Handle Handler 1 Reactor (central component) waits for incoming events and demultiplexes & dispatches each event (i.e., calls your Handler which is supposed to deal with this event) Handlers must implement a predefined interface Handle is a unique value of a particular type (e.g., interrupts, Unix handles) that determines to which handler an event will be dispatched Handler 2 Handlers are interested in certain types of events and register for this type with the Reactor or are hardwired • • • Events can be prioritized Handlers may run concurrently Dispatching tasks to a thread in a multicore system is possible, but very complex (to do it right)
  29. 29. Recommended Design Approach In most projects, finite state machines (FSM) (together with timing diagrams) are the best choice for design activities 1. 2. 3. 4. 5. Define the problem (space) and check the requirements Elaborate all program flows that are necessary (but also consider error scenarios!) Determine the states the system must support as well as the transitions incl. the actions to be called for a particular transition Check and optimize the FSM Implement it with the table approach or generate it
  30. 30. Host/Target Development Host Target USB Test Environment IDE Bootloader starts on reset Command Line ICSB port for programming other firmware CrossCompiler Development Environment Developing Cross-Compiling Testing on Simulator or Physical Target
  31. 31. Developer Ecosystems Arduino native IDE MariaMole: alternative IDE CodeBlocks for AVR & Arduino Arduino for Microsoft Visual Studio and Atmel Studio (free). Plug-In with features of the Arduino IDE, optional USB/WiFi debugger Arduino Eclipse Plug-In Arduino-Devel: ant-scripts for Eclipse instead of plug-in Eclipse & AVR PlugIn embedXcode: Apple’s Xcode MiniBloq: Graphical UI More details on the Arduino Playground: http://playground.arduino.cc/
  32. 32. Java VM on Arduino HaikoVM runs on Arduino and implements Java 6 bytecode Runs on AVR ATmega8, AVR ATmega328p (and Windows, UNIX) A lot of nice features: Preemptive threads & Synchronization Exceptions ... Workflow 1. 2. 3. 4. Java to Class Class to C C to Binary Upload and Run Work still ongoing
  33. 33. Learning by Example Examples are helpful to introduce Arduino concepts Thanks to Mike McRoberts for providing a free manual with various experiments (see below) In theory, theory and practice are the same. In practice, they are not. http://math.hws.edu/vaughn/cpsc/226/docs/askmanual.pdf
  34. 34. Arduino Projects I will demo one of my own experiments The other projects are actually taken from the Arduino Playground: http://playground.arduino.cc// main/projects ... so that you can find detailed instructions, part lists, etc. on the Web. Uncountable Arduino projects availabe that may give you inspiration for your own experiments But don‘t go too far!
  35. 35. Project Traffic Light Building a Traffic Light with LEDs and a Piezo speaker that signals red or green.
  36. 36. Example 1: Debouncing Problem: when pressing a switch or button the signal can bounce for a while Solution: Debouncing pattern
  37. 37. Example 1 – Code (Setup) // constants won't change. They're used here to set pin numbers: const int buttonPin = 2; // the number of the pushbutton pin const int ledPin = 13; // the number of the LED pin // Variables will change: int ledState = HIGH; int buttonState; int lastButtonState = LOW; // the current state of the output pin // the current reading from the input pin // the previous reading from the input pin long lastDebounceTime = 0; // the last time the output pin was toggled long debounceDelay = 50; // the debounce time; increase if output flickers void setup() { pinMode(buttonPin, INPUT); pinMode(ledPin, OUTPUT); // set initial LED state digitalWrite(ledPin, ledState); }
  38. 38. Example 1 – Code (Loop) void loop() { // read the state of the switch into a local variable: int reading = digitalRead(buttonPin); // If the switch changed, due to noise or pressing: if (reading != lastButtonState) { // reset the debouncing timer lastDebounceTime = millis(); } if ((millis() - lastDebounceTime) > debounceDelay) { // whatever the reading is at, it's been there for longer // than the debounce delay, so take it as the actual current state: // if the button state has changed: if (reading != buttonState) { buttonState = reading; // only toggle the LED if the new button state is HIGH if (buttonState == HIGH) { ledState = !ledState; } } } digitalWrite(ledPin, ledState); // set the LED lastButtonState = reading; // this will be the lastButtonState in the next loop }
  39. 39. Alternative Solution Using the Debounce Library (DRY) Available in the Arduino IDE Implements the same functionality in an elegant way // This code turns a led on/off through a debounced switch #include <Debounce.h> #define SWITCH 5 #define LED 13 // Instantiate a Debounce object with a 20 millisecond debounce time Debounce debouncer = Debounce( 20 , SWITCH ); void setup() { pinMode(SWITCH,INPUT); pinMode(LED,OUTPUT); } void loop() { // Update the debouncer debouncer.update ( ); // Get the update value digitalWrite(LED, debouncer.read() ); }
  40. 40. Example 2: Pull-Up Resistors PullProblem: circuits are subject to electrical fluctuations which may lead to an undefined state. Solution: use a pull-up resistor so that when unpressed, 5V will be on pin 2, and when pressed will be low to connection with ground Arduino internally provides Pull-Up resistors for digital pins
  41. 41. Example 2 – Code void setup(){ Serial.begin(9600); // start serial connection pinMode(2, INPUT_PULLUP); // pin 2 is input and uses the pull-up resistor pinMode(13, OUTPUT); } void loop(){ //read the pushbutton value into a variable int sensorVal = digitalRead(2); //print out the value of the pushbutton Serial.println(sensorVal); // send current value via serial communication to host // // // // if Keep in mind the pull-up means the push-button's logic is inverted. It goes HIGH when it's open, and LOW when it's pressed. Turn on pin 13 when the button's pressed, and off when it's not: (sensorVal == HIGH) { digitalWrite(13, LOW); } else { digitalWrite(13, HIGH); } }
  42. 42. Example 3: Using PWM Problem: for dimming a led, ..., we need to change the actual current continuously, but how? Solution: Use PWM (PulseWidth-Modulation) to simulate an analog output with variable current Done by swítching the signal on and off for specific time intervals (duty cycles)
  43. 43. Example 3 – Code int ledPin = 9; // LED connected to digital pin 9 void setup() { // nothing happens in setup } void loop() { // fade in from min to max in increments of 5 points: for(int fadeValue = 0 ; fadeValue <= 255; fadeValue +=5) { // sets the value (range from 0 to 255): analogWrite(ledPin, fadeValue); // analog write on digital pin! // wait for 30 milliseconds to see the dimming effect delay(30); } // fade out from max to min in increments of 5 points: for(int fadeValue = 255 ; fadeValue >= 0; fadeValue -=5) { // sets the value (range from 0 to 255): analogWrite(ledPin, fadeValue); // wait for 30 milliseconds to see the dimming effect delay(30); } }
  44. 44. Example 4: Using Libraries Problem: How can we access the LiquidChrystal display Solution: we need to import the LiquidChrystal Library
  45. 45. Example 4 – Code #include <LiquidCrystal.h> // the library for using LCDs // initialize the library with the numbers of the interface pins LiquidCrystal lcd(12, 11, 5, 4, 3, 2); void setup() { // set up the LCD's to 16 numbers and 2 rows lcd.begin(16, 2); // Print a message to the LCD. lcd.print("hello, world!"); } void loop() { // set the cursor to column 0, line 1 // (note: line 1 is the second row, since counting begins with 0): lcd.setCursor(0, 1); // print the number of seconds since reset: lcd.print(millis()/1000); }
  46. 46. Example 5: Control Speed of DC Motor Problem: Connecting a low current Arduino with a high current consumer Solution: Transistor (npn) to separate both circuits Potentiometer to let user avry the speed Diode to prevent any current caused by induction damaging the circuit Source: http://www.dummies.com/how-to/content/how-to-control-the-speed-of-a-dc-motor-with-the-ar.html
  47. 47. Example 5 – Code int int int int potPin = A0; // potentiometer on analog pin A0 motorPin = 9; // motor on digital pin 9 potValue = 0; motorValue = 0; void setup() { Serial.begin(9600); } void loop() { potValue = analogRead(potPin); // map maps from [0, 1023] to [0, 255] motorValue = map(potValue, 0, 1023, 0, 255); analogWrite(motorPin, motorValue); // set speed Serial.print("potentiometer = " ); Serial.print(potValue); Serial.print("t motor = "); Serial.println(motorValue); delay(2); }
  48. 48. Alternative Solution Use a motor shield (several available) Can support multiple motors (brushed dc motor, stepper, servo) Motor shields leverage the H-bridge L298P
  49. 49. Alternative – Code (Setup) const int PWM_A = DIR_A = BRAKE_A = SNS_A = 3, 12, 9, A0; void setup() { // Configure the A output pinMode(BRAKE_A, OUTPUT); pinMode(DIR_A, OUTPUT); // Brake pin on channel A // Direction pin on channel A // Open Serial communication Serial.begin(9600); Serial.println("Motor shield DC motor Test:n"); }
  50. 50. Alternative – Code (Loop 1) void loop() { // Set the outputs to run the motor forward digitalWrite(BRAKE_A, LOW); digitalWrite(DIR_A, HIGH); // setting brake LOW disable motor brake // setting direction to HIGH: motor will spin forward analogWrite(PWM_A, 255); // Set the speed of the motor, 255 is the max value delay(5000); // hold the motor at full speed for 5 seconds Serial.print("current consumption at full speed: "); Serial.println(analogRead(SNS_A)); // Brake the motor Serial.println("Start brakingn"); // raising the brake pin the motor will stop faster than the stop by inertia digitalWrite(BRAKE_A, HIGH); // raise the brake delay(5000); // to be continued
  51. 51. Alternative – Code (Loop 2) // … continued // Set the outputs to run the motor backward Serial.println("Backward"); digitalWrite(BRAKE_A, LOW); digitalWrite(DIR_A, LOW); // setting againg the brake LOW to disable motor brake // now change the direction to backw: LOW DIR_A pin analogWrite(PWM_A, 255); // Set the speed of the motor delay(5000); Serial.print("current consumption backward: "); Serial.println(analogRead(SNS_A)); // now stop the motor by inertia, motor will stop slower than with brake function analogWrite(PWM_A, 0); // turn off power to the motor Serial.print("current brake: "); Serial.println(analogRead(A0)); Serial.println("End of the motor shield test with DC motors. Thank you!"); while(1); }
  52. 52. Example 6: Interface to Processing Problem: How can we access Arduino from Processing? Solution: use the Processing library Based on Firmata: generic protocol for communicating with microcontrollers like the Arduino from software on a host computer. Guess, where the Arduino IDE came from. Processing was developed as a subset of Java to support visual artists, designers, young programmers, .... It provides stunning Animation, Simulation, Graphics.
  53. 53. Example 6 – Code import processing.serial.*; import cc.arduino.*; Arduino arduino; int ledPin = 13; void setup() { //println(Arduino.list()); // we assume it is the first device arduino = new Arduino(this, Arduino.list()[0], 57600); arduino.pinMode(ledPin, Arduino.OUTPUT); } void draw() // draw is the Processing cousin of loop { arduino.digitalWrite(ledPin, Arduino.HIGH); delay(1000); arduino.digitalWrite(ledPin, Arduino.LOW); delay(1000); }
  54. 54. Libraries If you want to provide a library you need to program in C/C++ Interface defined in header file, implementation in c++ file /* Header file specifies public contract */ /* The Implementation File */ #ifndef Loudspeaker_h #define Loudspeaker_h #include <Loudspeaker.h> const byte SPEAKER_PIN = 0x8; class Loudspeaker { Loudspeaker(); ~Loudspeaker(); public: void playTone(int freq); void shutUp(); } #endif Compile with gcc-avr //constructor Loudspeaker::Loudspeaker() { pinMode(SPEAKER_PIN, OUTPUT); } Loudspeaker::~Loudspeaker() { /* NOP */ } void Loudspeaker::playTone(int freq) { /* ... */ } void Loudspeaker::shutUp() { /* ... */ }
  55. 55. Arduino Simulators Simulator for those with limited tinkering capabilities or without interest Virtronics not perfect, but so far the best solution I found (14,95 AUD) Running my Traffic Lighht example
  56. 56. Netduino „Arduino.NET“ Shield-compatible with Arduino Uno Rev. 3 Based on .NET Micro Framework Supports C#, VB, ... STMicro 32-bit microcontroller Speed: 168MHz, Cortex-M4 Code Storage: 384 KB RAM: 100+ KB 10 mbps Ethernet Micro SD card support up to 2 GB Input Voltage: 7.5 - 9.0 VDC or USB powered 25 mA max. current per pin Digital I/O 3.3 V but 5 V tolerant 12 bit ADC (Analog Digital Converter) USB For both images: (c) Microsoft
  57. 57. Blinking LED in Netduino In Visual Studio: Change deployment target from emulator to the real board (in the „project menu“ visit „Hello_LED properties“. There you‘ll find the „.NET Micro Framework“ where you eventually change the transport type to „USB“) using System; using System.Threading; using Microsoft.SPOT; using Microsoft.SPOT.Hardware; using SecretLabs.NETMF.Hardware; using SecretLabs.NETMF.Hardware.Netduino; namespace Hello_LED { public class Program { public static void Main() { OutputPort LED = new OutputPort(Pins.ONBOARD_LED, false); while (true) { LED.Write(true); Thread.Sleep(250); LED.Write(false); Thread.Sleep(250); } /* while */ } /* Main() */ } //* Program */ } //* Hello_LED */
  58. 58. EventEvent-Driven Netduino Event-driven system-level example using .NET eventhandlers /* imports as in the Blinking LED example */ namespace EventDrivenLED { public class Program { static OutputPort LED = new OutputPort(Pins.ONBOARD_LED, false); public static void Main() { InterruptPort button = new InterruptPort(Pins.ONBOARD_SW1, false, Port.ResistorMode. Disabled, Port.InterruptMode.InterruptEdgeBoth); button.OnInterrupt += new NativeEventHandler(button_OnInterrupt); Thread.Sleep(Timeout.Infinite); } //* Main() */ static void button_OnInterrupt(uint inf1, uint inf2, DateTime time) { // inf1: id of the button, inf2: button state LED.Write(inf2 == 0); // true => button was pushed } /* button_OnInterrupt */ } /* Program */ } /* EventDrivenLED
  59. 59. Raspberry Pi more a cheap ARM6-based PC to go with size of a credit card With 1 GHz, 512 MB RAM, separate Broadcom Graphics processor, HDMI. Often used as media center (XBMC) Created by the Raspberry Pi Foundation. „PI“ originally came from „Python Interpreter“. Not fully open source! GNU/Linux (Raspbian), or other OS loaded from a SD card Voltage 5V (Micro-USB or batteries) Ports: 17 Digital GPIO-Pins, SPI, I²C, UART, EGL Caution: Ports can only handle 3.3V GPIO = General Purpose I/O SPI = Serial Peripheral Interface EGL = Programming Interface: shields APIs (OpenGL, ...) from the underlying windowing system
  60. 60. Using the GPIO Pins Different choices: Python, favourite language of the RPi creators Unix Shell: writing 1 to the port 17 with the program gpio: gpio -g write 17 1 C/C++ Javascript Java HTML5 Perl import RPi.GPIO as GPIO import time /* use board pin numbers */ GPIO.setmode(GPIO.BOARD) /* use it as an output port */ GPIO.setup(11, GPIO.OUT) def helloRPi(pin): GPIO.output(pin,GPIO.HIGH) time.sleep(1) GPIO.output(pin,GPIO.LOW) time.sleep(1) return Erlang for i in range(0,1000): helloRPi(11) ... GPIO.cleanup()
  61. 61. Expanding the Raspberry Pi Limited capabilities compared with Arduino Various shields available, e.g.: Shield to connect Raspberry Pi & Arduino Shield to expand the capabilities of RPi The Gert Board is a well known expansion board Sold assembled and not assembled 12 x Buffered I/O 3 x Push Buttons 6 x Open collector drivers (50V, 0.5A) 18V, 2A motor controller 28-pin dual in line ATmega microcontroller 2 -channel 8, 10, or12 bit Digital to Analog converter 2- channel 10 bit Analog to Digital converter
  62. 62. beagleboard.org beagleboard.org - BeagleBone BeagleBone Black, the sprinter: Powered by Embedded Linux CPU AM335x 1GHz ARM® Cortex-A8 512MB DDR3 RAM 2GB 8-bit eMMC on-board flash 3D graphics accelerator NEON floating-point accelerator 2x PRU 32-bit microcontrollers Connectivity USB client for power & communications USB host Ethernet HDMI 2x 46 pin headers • PRU • PMIC = Programmable Realtime Unit = Power Management IC
  63. 63. BeagleBone External Interface Pins Satisfaction guaranteed
  64. 64. BeagleBone Programming Supports Python, Perl, C/C++, JVM Languages, JavaScript + BoneScript Library, Shell commands, ... Can interact with Arduino serially using Java RxTx Eclipse,Visual Studio, Cloud9 support JavaScript + BoneScript var b = require('bonescript'); var state = b.LOW; b.pinMode("USR0", b.OUTPUT); b.pinMode("USR1", b.OUTPUT); b.pinMode("USR2", b.OUTPUT); b.pinMode("USR3", b.OUTPUT); setInterval(toggle, 1000); function toggle() { if(state == b.LOW) state = b.HIGH; else state = b.LOW; b.digitalWrite("USR3", state); }
  65. 65. And the rest? pcDuino: Arduino + Android or Linux Nanode: Actually, an extended Arduino Libelium Waspnode: Designed for Wireless Sensor Networks, uses the Arduino IDE, for Arduino sketches - only some adjustments necessary ... CubieBoard, PandaBoard, ... Mona Lisa built with hardware (c) http://karachi.olx.com.pk/
  66. 66. What we didn‘t hear This was the tip of the iceberg In practice, we face additional challenges: Multitasking and Synchronization Board-to-Board Communication Native tools „ilities“ such as Safety Real-time requirements Developing Drivers Evolution and Update Product Families Testing & Debugging ... Nonetheless, the capabilities of open source hardware as well as its wide acceptance are more than promising. Wiring is fun!
  67. 67. Robotics For robotics applications you may use Arduino, Raspberry Pi, BeagleBone et al. but that is tedious Often, special robotics kits may be the better choice, e.g., Lego Mindstorms EV3 Not open source but often used for prototyping or demos Contains NI LabVIEW, a graphical programming environment.You may also use: LeJOS implements Java and provides its own firmware RobotC ... many further options ...
  68. 68. State-of-theState-of-the-Art Software is essential for embedded devices Only a few systems today aren‘t based on software Today‘s microcontrollers are several orders of magnitudes more powerful than an Intel 8051 Open Source Hardware helps to learn the fundamentals of embedded systems (development) to build prototypes to create commercial systems to implement physical computing devices that interact with users and the Web to have fun Most systems can be programmed using comfortable IDEs But don‘t let the IDEs fool you. Embedded systems differ significantly from desktop systems, e.g., Hard resource constraints (small memory, short battery lifetime, less speed, ...) Time as a first order concept Integration with electronics, mechatronics, mechanics, ... Dependability and Safety Testing & Simulators Updates of (mobile) devices
  69. 69. Future Trends The Future is Embedded Modern cars contain a network with several dozens interconnected embedded systems In „hardware“-companies like Siemens two thirds of revenues depend on software. And this number is increasing. There are far more embedded systems than other systems, but they are usually hidden in a box Connected embedded systems become commodity products (example: cars, home automation) New types of HMI (Human Machine Interaction) Robotics on the rise Arduino-based or not? Resistance is futile Human-Machine Interaction
  70. 70. Conclusions Open source hardware boards offer a cheap and easy way to dive into embedded systems Arduino & Raspberry Pi & Beaglebone are the VIPs Arduino is superior for pure electronics projects, but Arduino Yun and Arduino Tre provide a Linux system, a microcontroller, and a bridge Raspberry Pi comprises a small Linux system BeagleBone: Arduino-like GPIO and Linux-based like Raspberry PI Netduino: interesting for .NET developers compatible with the Arduino board layout (shield compatible) BeagleBone and other boards http://hacknmod.com/hack/make-a-uav-spyplane-using-the-arduino/ • Dear NSA, the community strikes back with an Arduinobased Drone! • Already available and much cheaper than the Euro-Hawk! are powerful but have less distribution Board selection based on need and available support Lego Mindstorms EV3 is excellent for learning robotics albeit commercial Solutions for connecting Arduino/Raspberry Pi, Arduino/ Mindstorms, ... already available Boards help to learn the pitfalls of developing embedded software without needing a safety net
  71. 71. Some folks won‘t ever give away their Arduino board Others would shamelessly steal it It is like a precious ring So, keep an eye on your ring micro controller board
  72. 72. Last Words:The Pain of Engineering The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at and repair. [Douglas Adams]
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