Arduino

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Hardware

Uno

The Arduino Uno is a microcontroller board based on the ATmega328 (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

This means that the Uno can execute 16 million 8 bit instructions per second.

Due

The Arduino Due is a microcontroller board based on the Atmel SAM3X8E ARM Cortex-M3 CPU (datasheet). It is the first Arduino board based on a 32-bit ARM core microcontroller. It has 54 digital input/output pins (of which 12 can be used as PWM outputs), 12 analog inputs, 4 UARTs (hardware serial ports), a 84 MHz clock, an USB OTG capable connection, 2 DAC (digital to analog), 2 TWI, a power jack, an SPI header, a JTAG header, a reset button and an erase button.

Since UNO is 8-bit and DUE is 32-bit, there is difference in terms of storage. On the Arduino Uno (and other ATMega based boards) an int stores a 16-bit (2-byte) value. This yields a range of -32,768 to 32,767 (minimum value of -2^15 and a maximum value of (2^15) - 1).

On the Arduino Due, an int stores a 32-bit (4-byte) value. This yields a range of -2,147,483,648 to 2,147,483,647 (minimum value of -2^31 and a maximum value of (2^31) - 1). See http://arduino.cc/en/Reference/int and Discussion of comparing UNO & Due.

Another interesting point is neither of them have floating point support (Beaglebone bone and Rasp Pi do have FP).

Comparison of Boards

Memory

  1. Flash memory (program space), is where the Arduino sketch is stored. Flash memory is the same technology used for thumb-drives and SD cards. It is non-volatile, so your program will still be there when the system is powered off.
  2. SRAM (static random access memory) is where the sketch creates and manipulates variables when it runs. This memory includes 3 kinds of space: static data, heap and stack.
  3. EEPROM is memory space that programmers can use to store long-term information.

Arduino IDE

Source code in Github

https://github.com/arduino/Arduino/tree/master/hardware/arduino/cores/arduino

Install Arduino IDE under Ubuntu

Using source code (For some reason, I cannot find ~/.arduino/preference.txt file with this approach) 

sudo apt-get install arduino-core
sudo apt-get install openjdk-7-jre
# Go to http://arduino.cc/en/main/software to download the latest software
tar xzvf arduino-1.0.5-linux32.tgz
cd arduino-1.0.5
sudo ./arduino

The 2nd approach is (I think it is better since I can find and modify ~/.arduino/preference.txt file). 

sudo apt-get update && sudo apt-get install arduino arduino-core

After Arduino IDE is installed, I can change the font (Line 11 of preference.txt file) from Monospaced DejaVu Sans Mono,plain,12 to something like 

editor.font=DejaVu Sans Mono,bold,16
OR
editor.font=Courier New,bold,16

PS. Open AbiWord to check available fonts in Ubuntu OS.

Arduino Reset Button

To "reset" the Uno power it down, hold down the reset button, and, while still holding the reset button down, power it up again. This will prevent the existing sketch from running. You can then upload a new sketch.

C users

Programming using Scratch

http://s4a.cat/

Since this will involve uploading a firmware to Arduino, we now can only do programming using S4A. We can go back to use Arduino IDE for programming if we want to discard using S4A.

s4a is available as deb package.

Simple example (button & LED)

  1. Connect wires according to http://s4a.cat/. I use 330 Ohm resistor. The digital pin I use is 3, not 2.
  2. sudo s4a to launch S4A
  3. Follow the instruction in instructables.com to try 1. LED blinking and 2. LED and button in S4A.

One problem with this idea is the arduino board needs to be connected to computer all the time.

Tutorials

StepperMotor.jpg

MicroServo.jpg

  • Check google to see the difference between dc motor and servo. This site explains the difference among dc motor, servo motor and step motor.

Arduino IDE, Books, Forums

IDE

Books

Forums

Processing/Graph

It is possible to send a byte of data from the Arduino to a personal computer and graph the result. This is called serial communication because the connection appears to both the Arduino and the computer as a serial port, even though it may actually use a USB cable.

  • First, download and install Processing software (currently 2.0.3)
  • Check out http://arduino.cc/en/Tutorial/Graph for wiring. Very simple. Just one potentiometer and 3 wires (one goes to gnd, 2nd one goes to 5v and the 3rd one connects to A0).
  • Check out http://www.dustynrobots.com/news/seeing-sensors-how-to-visualize-and-save-arduino-sensed-data/ for the idea of how to plot the analog data using Processing. It contains 2 steps: 1. Open Arduino IDE (sudo is necessary if OS is not Windows) and compile/run a code to print byte to serial using Serial.write(). 2. Open Processing (sudo is necessary if OS is not Windows) and run a code. We shall be able to see a beautiful streaming graph appearing on screen. Both codes are attached below.

Arduino 

int sensorPin = A0;    // analog input pin to hook the sensor to
int sensorValue = 0;  // variable to store the value coming from the sensor
 
void setup() {
  Serial.begin(9600); // initialize serial communications
}
 
void loop() {
  sensorValue = analogRead(sensorPin)/4; // read the value from the sensor
  Serial.write(sensorValue); // print bytes to serial
  delay(10);
}

Processing 

import processing.serial.*;
Serial myPort;        // The serial port
float xPos = 0;             // horizontal position of the graph
 
void setup () {
  size(800, 600);        // window size
 
  // List all the available serial ports
  println(Serial.list());
 
  String portName = Serial.list()[0];
  myPort = new Serial(this, portName, 9600);
 
  background(#EDA430);
}
 
void draw () {
  // nothing happens in draw.  It all happens in SerialEvent()
}
 
void serialEvent (Serial myPort) {
  // get the byte:
  int inByte = myPort.read();
  // print it:
  println(inByte);
 
  float yPos = height - inByte;
  // draw the line in a pretty color:
  stroke(#A8D9A7);
  line(xPos, height, xPos, height - inByte);
 
  // at the edge of the screen, go back to the beginning:
  if (xPos >= width) {
    xPos = 0;
    // clear the screen by resetting the background:
    background(#081640);
  }
  else {
    // increment the horizontal position for the next reading:
    xPos++;
  }
}

ProcessingPotentiometer.png


More:

Robot based on BOE shield for Arduino

My robot is based on 'Shield for Arduino' which means I can use Arduino IDE + C code style to write my code instead of using PBASIC programming which is used in another similar robot.

Projects from each chapters

Chapter 3. Activity 2: Re-test the servos

We can use Pins 11 and 12 instead of 12 and 13. Be sure to adjust your code accordingly.

Chapter 4. Activity 2

First time we disconnect robot from the computer and let it go (forward, left turn, right turn and back ward).

Chapter 5 (Whiskers). Activity 3 or 4

See my robot is in action on http://www.youtube.com/watch?v=sjzQI6GHe3w.

Robot whisker.jpg

Chapter 7 (Infrared headlight). Activity 4

Similar to Chapter 5 but IR detectors are used. See the robot in action on http://www.youtube.com/watch?v=K5pIZ5XcP7Y.

Activity 7: Drop-off detection (Very Cool).

Robot Infrared.jpg

This site contains some more information to use infrared LED to avoid object by testing on arduino board.

Using regular IR remote controll

The Arduino code provided for this project makes the BOE Shield-Bot recognize Sony IR remote signals only! For example, the BRIGHTSTAR universal remote sold by Parallax is programmed by holding the SET-UP button down until an LED on the remote lights up, then entering the code 605. Different models of remotes may use different codes and configuration methods. Check your remote's docs! See the instruction and arduino code in IR Remote Controlled Shield-Bot.

Using ping))) with BOEShield

Information and arduino code from Parallax. I find the code by searching within parallax.com. See http://thoughtfix.com/blog/2012/3/25/arduino-boe-shield-ping-and-a-servo.html for arduino code. Some modified code here. My recorded video is available on Youtube.

Robot ping.jpg

Other robots

Video

The astounding athletic power of quadcopters from TED.

Projects

Simple LED

GND --- wire --- 300 Ohm --- short end of LED --- long end of LED --- wire --- 5v/3.3v.

The 300 Ohm resistor can be replaced by anyone between 100 Ohm and 10K Ohm.

7 Segment LED

7segmentLED.jpg

Using Web to read/write GPIO (it works)

http://uggettif.blogspot.com/2012/11/controlling-arduino-from-web-page.html

Using Node/Websocket to create a Web page and control Arduino

Test Ethernet Shield

Use sketch_12_01_dhcp from Programming Arduino Next Steps. Or 

// sketch_12_01_dhcp
#include <SPI.h>
#include <Ethernet.h>

byte mac[] = { 0x00, 0xAA, 0xBB, 0xCC, 0xDE, 0x02 };

void setup() 
{
  Serial.begin(9600);
  while (!Serial){};

  if (Ethernet.begin(mac)) 
  {
    Serial.println(Ethernet.localIP());
  }
  else
  {
    Serial.println("Could not connect to network");
  }
}

void loop() 
{
}

Open Serial Monitor. Mine shows 10.42.0.37 when I use ethernet 1 from PC to share the internet connection.

Arduino with bluetooth

Bluetooth.jpg

Accelerometers & Gyroscopes

Adxl345.jpg

Python and Arduino

Monitor a movement (serial port) and send an email

http://learn.adafruit.com/arduino-lesson-17-email-sending-movement-detector/python-code

The arduino program is launched first. The arduino is used to send messages and python is used to read messages. So arduino program can be run without a Python program.

Monitor files and send signals to LED

Write one arduino and one python file http://www.joakimlinde.se/microcontrollers/arduino/ or http://www.olgapanades.com/blog/controlling-arduino-with-python/

See also arduino.cc website for mire info about Python talking to Arduino via a serial interface.

Electronics

Clock cycles

The following code was used to measure the time spent on running 2 statements: one is delay(1000) and the other is Serial.println(). I got an output of 8 (most of time) or 4 (few times) microseconds. The code was modified from Arduino Reference, this discussion or another discussion.

Recall that nano second=10^(-9) second and micro second = 10^(-6) second. On 16 MHz Arduino boards (e.g. Duemilanove and Nano), this function has a resolution of four microseconds (i.e. the value returned is always a multiple of four). 

unsigned long time;

void setup(){
  Serial.begin(9600);
}
void loop(){
  Serial.print("Time: ");
  time = micros();
  delay(1000);    // wait a second so as not to send massive amounts of data
                        // We can also move this line to the end of loop() function to see the difference
  Serial.println(micros() - time);
}

If loop is empty, it will run at 16 MHz. If toggling a PIN is only line inside loop, it will run 16x10^6/2 loops since toggling a PIN took 2 clock cycles.

On a slightly more complex example, 

unsigned long time;

void setup(){
  Serial.begin(9600);
}
void loop(){
  Serial.print("Time: ");
  time = micros();
  int angle = 0;
  while(angle < 180)
    Serial.println(sin(angle++/57.295));    
  Serial.println(micros() - time);
  
  // wait a second so as not to send massive amounts of data
  delay(1000);
}

it took 1061804 microseconds on my Arduino UNO; that is 16*10^6/10^6 * 1061804/ instructions to execute. Here, 16*10^6 number denotes 16 MHz of the CPU and 10^6 denotes the number of micro seconds. In other words, there are billions of instructions were executed in 4 lines.

Instruction <> Cycle

http://forum.arduino.cc/index.php/topic,4324.0.html

Calculate resistor value for LED

To figure out which resistor to use I used the formula: R = (V1 - V2) / I

where: V1 = power supply voltage, V2 = LED voltage, I = LED current (usually 20mA which is .02A).

For example, my LED is 1.7V, it takes 20mA (which is .02 A) of current and my supply is 4.5V. So the math is...

R = (4.5V - 1.7V) / .02 A = 140 ohms

Also putting LEDs in series would add voltages together while in parallel won't add voltages but draw more current. That is if we put LEDs together, we need to multiply the current that one LED draws by the total number of LEDs I was using.

If we putting resistors in series, it would add ohms. But we put resistors in parallel, it would reduce resistance.

Timer

http://www.nunoalves.com/classes/spring_2012_cpe355/cpe355-02-f.pdf

Battery

http://gammon.com.au/power

Ah (Amp Hour)

http://overlandresource.com/what-is-an-amp-hour-and-how-to-calculate-battery-capacity

Interrupt

http://www.nunoalves.com/classes/spring_2012_cpe355/cpe355-02-b.pdf

See Chapter 3 of Programming Arduino Next Steps. On Arduino UNO, there are 2 interrupts (PIN 2 and 3). A simple sketch to test interrupts (using attachInterrupt function) is 

// sketch 03_01_interrupts
int ledPin = 13;
void setup()
{
  pinMode(ledPin, OUTPUT);
  attachInterrupt(0, stuffHapenned, FALLING;
}

void loop() { }

void stuffHapenned()
{
  digitalWrite(ledPin, HIGH);
}

Note that PIN 13 has an LED (also know "L" LED since there is a label "L" next to it) connected on UNO board so we don't need to manually connect another LED. See Arduino.cc website.

PWM/Analog Output

See Chapter 1 of Programming Arduino Next Steps - Analog output. It also teaches how to use multimeter to measure analog output <Sketch_01_07_pwm>. It is noted that UNO does not have true analog output (Arduino Due has). On Arduino UNO board, the pins marked with little "~" (pins 3,5,6,9,10 and 11) can be used as analog outputs (with the analogWrite function).

See Chapter 3 of Programming Arduino Next Steps <Sketch_03_03_1kHz>.

Memory

I2C/TWI

SPI

UART

USB Programming

Network Programming

Digital Signal Processing

Writing Library

Relay module shield

Embedded System

Introduction to Embedded Systems: Using ANSI C and the Arduino Development Environment by David Russell (Author), Mitchell Thornton (Series Editor)

Seller, Community

The CanaKit's Sparkfun inventor's kit for Arduino (SX10173) contains lots of stuff like 1N4148 diode, P2N222AG NPN transistor (youtube, potentiometer, 5V relay, temperature sensor, 74HC595 shift register, hobby servo and photo resistor/photocell. Circ-03 (or Circ-12 on the new guide) teaches how to use P2N222AG transistor and 1N4001 Diode to spin a motor. See the SIK guide in pdf from the above link. The resistors it has included have 330 ohm, 10K. I also purchased 3.3M resistors for another application.

In the Arduino budget pack, it includes 100 ohm, 1k and 10k resistors and photocell.

http://lifehacker.com/how-can-i-get-into-a-new-hobby-without-breaking-the-ban-489189582

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