Proyek Teknologi: Maret 2014

Sabtu, 29 Maret 2014

Xathrya Sabertooth

Posted: 28 Mar 2014 04:44 AM PDT

Traffic lights, also known as traffic signals, traffic lamps, signal lights, stop lights, or technically as traffic control signals are signalling device positioned at road intersection, pedestrian crossings, and other locations to control competing flows of traffic.

In this project we will create a simple “traffic light”, imitating what traffic light does and program it using Arduino.

Objective

Three light switch each other to perform a simple traffic light.
Multiple digital signal output.
The order of light in one cycle: red – yellow – green – yellow

Prerequisite

Blinking LED

Requirement

Following is all materials I use for this tutorial.

Arduino Uno R3
LEDs ( red x1, yellow x1, green x1 )
Resistor 10k ohm x3

You can change the Arduino board to higher specification if you like.

Because we want to do this as realistic as we can, we will use three different LED: one red LED, one yellow LED, one green LED.

The resistors should be 1/4 Watt resistors with resistance value of 10k ohm. You can use resistors of any band.

You also need an USB A to B cable for upload our program to our Arduino.

Circuit

Here is the circuit image, created using Fritzing.

We use three LED at once. The first LED is red, the second LED should be yellow, and the last one is green LED. Remember which one is the positive leg and which one is negative leg (anode and cathode) for each LED. Connect attach the long leg of an LED (positive leg or anode) with resistor and then connect it to corresponding pin. Red one will use pin 12, yellow will be in 11, and green would use pin 10. Connect the short leg (negative leg or cathode) to the ground (GND).

Code

Let’s see what code we use for this project and discuss it later.

#define RED_PIN 12  #define YELLOW_PIN 11  #define GREEN_PIN 10      // timeout for each LED in second  int timeout[3] = {10, 1, 20};  int currentLED = 0;  int alternate = -1;    int enumLED[3] = { RED_PIN, YELLOW_PIN, GREEN_PIN };    void setup() {    pinMode(RED_PIN, OUTPUT);    pinMode(YELLOW_PIN, OUTPUT);    pinMode(GREEN_PIN, OUTPUT);  }    void loop() {    digitalWrite(enumLED[currentLED], LOW);    if (currentLED == 0) {      alternate = 1;    } else if (currentLED == 2) {      alternate = -1;    }    currentLED = currentLED + alternate;    digitalWrite(enumLED[currentLED], HIGH);      delay(timeout[currentLED] * 1000);  }

We define three constant here: RED_PIN, YELLOW_PIN, and GREEN_PIN for red, yellow, and green LED respectively. However this time we only define it using macro not as constant. Then we create an array of LED as enumLED. This array will be our shortcut to switch between LED. For indexing we use currentLED variable.

The timeout array is an array which stored delay interval for each LED in seconds. This means our lights won’t turned on in same duration.

The alternate variable is used to increment the currentLED index. Remember that in one cycle, we define the LED switching as red – yellow – green – yellow.

Result

LED is turned on in following order:

red for 10 seconds
yellow for 1 second
green for 20 seconds
yellow for 1 second
red for 10 seconds at another cycle.

Why it Works

Our code is as simple as turned off current LED and turned on the next LED. The previous, current, and next LED are defined in an array and we use currentLED variable as an index. The alternate is used to increase or decrease the index and make our LED obey our pattern.

Jumat, 28 Maret 2014

Xathrya Sabertooth

Arduino Project: Toggle the LED with Push Button
Arduino Project: Push Button
Arduino Project: Software Serial Communication
Arduino Project: Turn On/Off LED using Serial Communication
Arduino Project: Simple Serial Communication

Arduino Project: Toggle the LED with Push Button

Posted: 27 Mar 2014 06:13 PM PDT

This project is upgrade of previous project (Simple Push Button). In this project, we just need to press the push button once to turn it on or off, instead of hold it.

Objective

Make the LED turn on or off by pressing the push button.

Prerequisite

Requirement

Following is all materials I use for this tutorial.

Arduino Uno R3
LED
Push button

You can change the Arduino board to higher specification if you like. The LED I use will emit red light as it is powered by electricity.

There are some kind of push button exists. In our project, we need only push button with four legs.

You also need an USB A to B cable for upload our program to our Arduino and also for serial communication.

Circuit

Here is the circuit image, created using Fritzing.

To build the circuit, attach the LED as shown in the figure. Attach the long leg of an LED (positif leg or anode) to pin 13. Attach the short leg (negative leg or cathode) to the ground (GND). On Arduino Uno, there is also a built in status LED which connected to pin 13. When our Arduino running successfully, both status LED and external LED will start to blink.

The push button has four legs (or four pins) as shown above. Two opposite pins connect when the button is pushed; otherwise, they are disconnected. In one side, we connect one leg to Arduino pin 7. In other side, we supply 5V electricity to one leg. The other leg is connected to a 10k ohm resistor before going to ground.

Code

Let’s see what code we use for this project and discuss it later.

const unsigned int BUTTON_PIN = 7;  const unsigned int LED_PIN = 13;    int old_button_state = LOW;  int led_state = LOW;    void setup() {    pinMode(LED_PIN, OUTPUT);    pinMode(BUTTON_PIN, INPUT);  }    void loop() {    const int CURRENT_BUTTON_STATE = digitalRead(BUTTON_PIN);      if (CURRENT_BUTTON_STATE != old_button_state &&        CURRENT_BUTTON_STATE == HIGH)    {      led_state = (led_state == LOW ? HIGH : LOW);      digitalWrite(LED_PIN, led_state);      delay(50);    }    old_button_state = CURRENT_BUTTON_STATE;  }

Notice that we define two constant here, LED_PIN which is for LED, and BUTTON_PIN for the push button. Both are defined as different purpose, the LED is output pin while the push button is input.

There is no significance change to our code from previous project. Things we can notice are the existence of two new variables: old_button_state and led_state.

Result

You should see that LED is turned on or off whenever we press the button.

Why it Works

We define a global variable named led_state to store the current state of our LED. It will be LOW when the LED is on and HIGH otherwise. In loop() we check the button’s current state. When we press the button, the switches is in HIGH logic and we toggle the content of led_state.

The global variable old_button_state is used to store the old state of push button. If we don’t do this, when we press and hold the button, the state will constantly be HIGH and we’d toggle the LED’s state continuously. Because this happens so fast it seems like the LED’s constantly on. When we release the button, the LED is in a more or less arbitrary state. Therefore we use previous push button to guard the state of LED.

Arduino Project: Push Button

Posted: 27 Mar 2014 05:17 PM PDT

Pushbutton is one of common component found in projects. The mechanism is simple, we press push button and we got a signal, otherwise it (should) gives nothing.

Objective

Make the LED turn on when we press the push button.
Make the LED turn off when we release the push button.

Prerequisite

Blinking LED

Requirement

Following is all materials I use for this tutorial.

Arduino Uno R3
LED
Push button

You can change the Arduino board to higher specification if you like. The LED I use will emit red light as it is powered by electricity.

There are some kind of push button exists. In our project, we need only push button with four legs.

You also need an USB A to B cable for upload our program to our Arduino and also for serial communication.

Circuit

Here is the circuit image, created using Fritzing.

Code

Let’s see what code we use for this project and discuss it later.

const unsigned int BUTTON_PIN = 7;  const unsigned int LED_PIN = 13;    void setup() {    pinMode(LED_PIN, OUTPUT);    pinMode(BUTTON_PIN, INPUT);  }    void loop() {    const int BUTTON_STATE = digitalRead(BUTTON_PIN);      if (BUTTON_STATE == HIGH) {      digitalWrite(LED_PIN, HIGH);    } else {      digitalWrite(LED_PIN, LOW);    }  }

Notice that we define two constant here, LED_PIN which is for LED, and BUTTON_PIN for the push button. Both are defined as different purpose, the LED is output pin while the push button is input.

Our code is as simple as checking the push button state and then output the corresponding voltage to LED.

Result

You should see that LED is turned on whenever we press the push button and turned off when we don’t. To keep the LED turned on, we have to keep pressing the push button.

Why it Works

Why do we need resistor for push button?

The problem is that we expect the push button to return a default value (LOW) in case it isn't pressed. But when the button isn't pressed,it would not be directly connected to ground and would flicker because of static and interference. A little bit of current flows through the resistor,and this helps prevent random noise from changing the voltage that the input pin sees.

When the button is pressed, there will still be 5 volts at Arduino’s digital pin, but when the button isn’t pressed, it will cleanly read the connection to the ground. We call this a pull-down resistor. That is, we have to connect the Arduino’s signal pin to power through the pushbutton and connect the other pin of pushbutton to ground using a resistor.

You can also wire this circuit the opposite way, with a pullup resistor keeping the input HIGH, and going LOW when the button is pressed. If so, the behavior of the sketch will be reversed, with the LED normally on and turning off when you press the button.

Arduino Project: Software Serial Communication

Posted: 27 Mar 2014 08:04 AM PDT

In most case, our device are stand-alone application, which means we don’t involve any additional computer for operation. However, we can still make Arduino interact with our computer in such nice way. We use serial communication to achieve this.

Most possible reason for communication is debugging purpose. We analyze Arduino state for various input and condition given, by reading output shown by Arduino. The serial communication can also be used for communication of two devices.

Arduino have built-in support for serial communication on pin 0 and 1, but what if we need more serial ports? Here come SoftwareSerial Library to rescue. This library has been developed to allow serial communication to take place on the other digital pins of our Arduino board, using software to replicate the functionality of the hardwired RX and TX lines. This can be extremely helpful when the need arises to communicate with two serial enabled devices, or to talk with just one device while leaving the main serial port open for debugging purpose.

Objective

Use pin 10 and 11 as virtual RX and TX serial lines.
Echo data received from main RX serial line to virtual TX line.
Echo data received from virtual RX line to main TX serial line.

Prerequisite

Simple Serial Communication

Requirement

Following is all materials I use for this tutorial.

Arduino Uno R3

You can change the Arduino board to higher specification if you like.

You also need an USB A to B cable for upload our program to our Arduino and also for serial communication.

Circuit

Here is the circuit image, created using Fritzing.

We don’t need any extra component to do this project.

Code

Let’s see what code we use for this project and discuss it later.

#include <SoftwareSerial.h>    SoftwareSerial EuSerial(10, 11);        // Bind RX and TX to pin 10 and 11    void setup() {    // Open serial communications and wait for port to open    Serial.begin(57600);    // Wait for serial port to connect. Needed for Leonardo only    while(!Serial);      Serial.println("Arduino SoftwareSerial Demo");      // Set the data rate for the SoftwareSerial port    EuSerial.begin(4800);    EuSerial.println("Hello, world?");  }    void loop() {    // Echo data from virtual RX to main TX    if (EuSerial.available())      Serial.write(EuSerial.read());    // Echo data from main RX to virtual TX    if (Serial.available())      EuSerial.write(Serial.read());  }

Here we have two serial line: Arduino serial and virtual serial by SoftwareSerial. Both have difference baud rate, the main lines have baud rate 57600 while the virtual lines have baud rate 4800.

The initialization of both lines are similar. We use begin() function to set the baud rate of both lines.

In loop(), we will echo every input we got. To do that, we should check the availability first. This is done by executing available(). To read data, Arduino use read() function. To send data to other end, Arduino provide print() and println() function. These functions are slight different where println() send extra new line character at the end of transmission.

Result

You need two serial lines connected to your PC. The result should be similar to Simple Serial Communication project. It is strongly recommended to use PuTTY and connect to both port recognized by your computer.

Why it Works

We have demonstrate serial communication in this project. The word serial means “one after the other”. Serial data transfer is a transmission method where data is transferred one bit at a time, one right after the other.

Information is passed back & forth between the computer and Arduino, by essentially, setting a pin high or low.

There are two condition of logic in circuit, HIGH and LOW. Some microcontrollers might define HIGH and LOW difference, but in Arduino Uno we have HIGH logic as 5V and LOW logic as 0V. If you know boolean value, yes this is boolean value with HIGH is true and LOW is false.

Arduino Project: Turn On/Off LED using Serial Communication

Posted: 27 Mar 2014 07:34 AM PDT

Objective

Input/Output from and to Arduino.
Make the LED turn on when we input certain command.
Make the LED turn off when we input certain command.

Prerequisite

Requirement

Following is all materials I use for this tutorial.

Arduino Uno R3
LED

You can change the Arduino board to higher specification if you like. The LED I use will emit red light as it is powered by electricity.

You also need an USB A to B cable for upload our program to our Arduino and also for serial communication.

Circuit

Here is the circuit image, created using Fritzing.

We don’t need extra resistor for this project, but make sure you are using pin 13. If you do connect it to other pin, it might be destroyed. The reason is that pin 13 has an internal resistor that other pins don’t have which limit current to our LED.

Code

Let’s see what code we use for this project and discuss it later.

const unsigned int LED_PIN = 13;  const unsigned int BAUD_RATE = 9600;    char command;    void setup() {     pinMode(LED_PIN, OUTPUT);     Serial.begin(BAUD_RATE);  }    void loop() {     if (Serial.available() > 0) {        command = Serial.read();        if (command == '1') {           Serial.println("Led on");           digitalWrite(LED_PIN, HIGH);        } else if (command == '2') {           Serial.println("Led off");           digitalWrite(LED_PIN, LOW);        } else {           Serial.println("Led pattern 1");           digitalWrite(LED_PIN, HIGH);           delay(250);           digitalWrite(LED_PIN, LOW);           delay(500);           digitalWrite(LED_PIN, HIGH);           delay(250);           digitalWrite(LED_PIN, LOW);        }        Serial.print("You enter: ");        Serial.println(command);     }  }

Notice that we define two constant here, LED_PIN which is pin we use, and BAUD_RATE for the baud rate. Baud rate is the rate of character transferred every second. Notice that 1 character is 1 byte, which is also 8 bit. Both party who communicate must agree on same baud rate before transmission began. If baud rate is not equal, data can’t be transferred correctly.

Here we introduce a object called Serial. This object handles input output in serial communication. To use this object we should initialize which baud rate we use. In this case we use 9600, which is common baud rate used.

To do input, we should check the availability first. This is done by executing Serial.available(). Single character can be read by read() function. To send data to other end, Arduino provide print() and println() function. These functions are slight different where println() send extra new line character at the end of transmission.

We define three commands: ’1′, ’2′, and ’3′. If we enter 1, we turn the LED on. If we enter 2, we turn the LED off. If we enter 3, we make the LED on/off in certain pattern.

Result

Once the program is uploaded, open “Serial Monitor” window in Arduino IDE. It is our tool to do serial communication using Arduino IDE. You can open it by navigate to Tool > Serial Monitor. Another way to do it is press CTRL + SHIFT + M at once.

To give input to Arduino, type in to the text box and click on “Send” button. Now give input of number 1, 2, 3 and see the result. You should see the LED are turned on and off according to your command.

Why it Works

It similar to project Simple Serial Communication where we received some commands from serial communication. This command are then processed to determine which routine should we do.

Arduino Project: Simple Serial Communication

Posted: 27 Mar 2014 06:27 AM PDT

Objective

Input/Output from and to Arduino.
Doing simple math operation and output the result.
Echoing the user inputs.

Prerequisite

none

Requirement

Following is all materials I use for this tutorial.

Arduino Uno R3

You can change the Arduino board to higher specification if you like.

You also need an USB A to B cable for upload our program to our Arduino and also for serial communication.

Circuit

Here is the circuit image, created using Fritzing.

We don’t need any extra component to do this project.

Code

Let’s see what code we use for this project and discuss it later.

const unsigned int BAUD_RATE = 9600;    int a = 5;  int b = 10;  int c = 20;    void setup() {    Serial.begin(BAUD_RATE);    Serial.println("Arduino Serial Communication Demo");      Serial.print("a = ");    Serial.println(a);      Serial.print("b = ");    Serial.println(b);      Serial.print("c = ");    Serial.println(c);      Serial.print("a + b = ");      // addition    Serial.println(a + b);      Serial.print("a * c = ");      // multiplication    Serial.println(a * c);      Serial.print("c / b = ");      // division    Serial.println(c / b);    Serial.print("b - c = ");      // subtract    Serial.println(b - c);  }    void loop() {    if (Serial.available()) {      Serial.write(Serial.read());    }  }

In the first line we declare a constant, BAUD_RATE, which has value 9600. Baud rate is the rate of character transferred every second. Notice that 1 character is equal to 1 byte or 8 bit. Both party who communicate using serial communication must agree on same baud rate before transmission began. If baud rate is not equal, data can’t be transferred correctly.

We declare three variables for our math operation: a, b, and c with their respective value. In setup() we do some basic math operation over these three variables. The result will be presented every time we initiate serial connection.

Result

Here we will be presented with the result of our math operation.

To give input to Arduino, type in to the text box and click on “Send” button. You will see nice similar message you type. Here is the result after I type “Satria Ady Pradana”:

Alternatively, you can use puTTY in Windows or Linux terminal in Linux. However we won’t cover this subject.

Why it Works

Information is passed back & forth between the computer and Arduino, by essentially, setting a pin high or low.

Rabu, 26 Maret 2014

Xathrya Sabertooth

Arduino Project: Simple Blinking LED

Posted: 25 Mar 2014 06:43 AM PDT

Blink LED, like what it should be, we make certain LED blinking. We can define “blinking” as continuous condition switching between ON and OFF condition. This is the simplest project we can do for Arduino.

Objective

Make LED blinking.

Prerequisite

Basic understanding of LED

Requirement

Following is all materials I use for this tutorial.

Arduino Uno R3
LED

You can change the Arduino board to higher specification if you like. The LED I use will emit red light as it is powered by electricity.

You also need an USB A to B cable for upload our program to our Arduino.

Circuit

Here is the circuit image, created using Fritzing.

Code

Let’s see what code we use for this project and discuss it later.

const unsigned int LED_PIN = 13;  const unsigned int PAUSE = 500;    void setup() {     pinMode(LED_PIN, OUTPUT);  }    void loop() {     digitalWrite(LED_PIN, HIGH);     delay(PAUSE);     digitalWrite(LED_PIN, LOW);     delay(PAUSE);     }

Notice that we define two constant here, LED_PIN which is pin we use, and PAUSE for the delay interval which is 500 ms.

The heart of this project is pin 13. We use this pin as output pin. Therefore we initialize pin 13 as an output pin with the statement:

pinMode(LED_PIN,OUTPUT);

Next in the main loop, we turn the LED on by:

digitalWrite(LED_PIN, HIGH);

and turn it off by:

digitalWrite(LED_PIN, LOW);

And we now know that digitalWrite() function is used to output signal on a pin.

The delay() command is used to tell Arduino to do nothing for given time. In our case, we make Arduino wait for 500 miliseconds.

Result

LED is blinking.

Why it Works

The LED we use is active-high LED, which means it can turn on when it is given HIGH voltage.

Selasa, 25 Maret 2014

Xathrya Sabertooth

Arduino and List of Arduino Boards

Posted: 24 Mar 2014 06:19 PM PDT

Arduino is an open source electronics prototyping platform based on flexible, easy-to-use hardware and software. It is a single board microcontroller intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environment.

A microcontroller (sometimes abbreviated as µC, uC, or MCU) is an integrated circuit contain a processor core, memory, and programmable input/output peripherals. One can program microcontroller for various purpose especially for control machinery, for example: robotics, automobile engine control systems, remote controls, toys, and other embedded systems. In short, microcontroller is similar to our brain, controlling input, process, and output of electronic device. This behavior similar to computer, however microcontroller already have memory, timer, and storage for store executable program.

A microcontroller can’t be used directly. It is a IC chip and we can’t use it immediately, which means we have to supply a minimum system to run it. That is analogically same with processor and motherboard. Fortunately, Arduino has provide all we need to utilize a microcontroller. Arduino has wrapped all the complicated things and provide us with nice programmable board without us to do extra work to create a system minimum.

The Boards

When we talk about Arduino, we are actually talking about Arduino family. There are some boards released by Arduino, designed using either Atmel AVR processor and ARM-based processor. The main differences between those boards are the:

Type of processor
Number of inputs and outputs
Form factor

An Arduino board is basically a single board with appropriate system and components enough to power and run a microcontroller. One Arduino product (Arduino board) might differs in some aspects when compared to another Arduino product. Arduino boards use megaAVR series of chips, specifically the ATmega8, ATmega 328, ATmega 1280, and ATmega 2560; and also ARM Cortex chips.

The boards include a 5 volt linear regulator. We can power Arduino board from power connector or from USB connector when we program it.

Most of Arduino products include 16MHz crystal oscillator (or ceramic resonator in some variants). Although some designes such as the LilyPad run at 8 MHz.

As stated before, Arduino is an open-source. Arduino exposed the schematics for all of their products, open to everyone. Anyone who interested can make their own arduino board. However, Arduino restricts that no one should use Arduino brand name for third party maker. That means, any company who create the Arduino clone cannot use Arduino name.

The Shields

Shields are printed circuit expansion boards that plug into the normally supplied Arduino pin-headers. Shields can provide motor controls, GPS, ethernet, LCD display, or any function specific to that shield. These peripherals are sold separately and can also be made by ourselves.

Programming in Arduino

Microcontroller is programmable, so does Arduino board which use microcontroller to run its awesomeness.

Arduino has official Integrated Development Environment (IDE) in use of programming for Arduino. The IDE is a cross-platform application written in Java and derived from the IDE for the Processing programming language and Wiring projects. It is designed to introduce programming to artists and other newcomers unfamiliar with software development. There are also alternative to Arduino IDE which you can see from this list.

Arduino programs are written in C or C++, however the structure is simplified. Arduino use software library called Wiring from original Wiring project which makes many common input/output operations much easier. We at minimum only need to define two function to make a runnable cyclic executive program:

setup(): a function run once at the start of a program that can initialize settings.
loop(): a function called repeatedly until the board powers off.

An example for simple source code (also called as “sketch”) which will blinks a LED on and off:

const unsigned int LED_PIN = 13;    void setup() {     pinMode (LED_PIN, OUTPUT);    // Enable pin 13 for digital output  }    void loop() {     digitalWrite(LED_PIN, HIGH);  // Turn on the LED     delay(1000);                  // Wait 1 second or 1000 miliseconds     digitalWrite(LED_PIN, LOW);   // Turn off the LED     delay(1000);                  // Wait 1 second  }

The programs compiled or created are in binary format which executable by the microcontroller. However this binary program is different with binary program in our computer. These programs use the different format, the mnemonic used by microcontroller.

The last step in programming Arduino is “upload” the program to Arduino. In common practice, uploading a program to microcontroller need external device called “programmer”. The fancy thing is, Arduino needs no external programmer. It has built component in board which allow our ordinary computer as programmer.

List of Boards

Arduino release numbers of board. This list might not be up to date. Please refer this page for more accurate Arduino product.

Arduino Uno
Arduino Leonardo
Arduino Due
Arduino Yùn
Arduino Tre
Arduino Micro
Arduino Robot
Arduino Esplora
Arduino ADK
Arduino Ethernet
Arduino Mega 2560
Arduino Mini
Arduino BT (BlueTooth)
LilyPad Arduino USB
LilyPad Arduino Simple
LilyPad Arduino SimpleSnap
LilyPad Arduino
Arduino Nano
Arduino Pro Mini
Arduino Pro
Arduino Fio

For quick comparison:

Name	Processor	Operating Voltage/Input Voltage	CPU Speed	Analog In/Out	Digital IO/PWM	EEPROM [KB]	SRAM [KB]	Flash [KB]	USB	UART
Uno	ATmega328	5 V/7-12 V	16 Mhz	6/0	14/6	1	2	32	Regular	1
Due	AT91SAM3X8E	3.3 V/7-12 V	84 MHz	12/2	54/12	-	96	512	2 Micro	4
Leonardo	ATmega32u4	5 V/7-12 V	16Mhz	12/0	20/7	1	2.5	32	Micro	1
Mega 2560	ATmega2560	5 V/7-12 V	16Mhz	16/0	54/15	4	8	256	Regular	4
Mega ADK	ATmega2560	5 V/7-12 V	16Mhz	16/0	54/15	4	8	256	Regular	4
Micro	ATmega32u4	5 V/7-12 V	16Mhz	12/0	20/7	1	2.5	32	Micro	1
Mini	ATmega328	5 V/7-9 V	16Mhz	8/0	14/6	1	2	32	-	-
Nano	ATmega168 ATmega328	5 V/7-9 V	16Mhz	8/0	14/6	0.512 1	1 2	16 32	Mini-B	1
Ethernet	ATmega328	5 V/7-12 V	16Mhz	6/0	14/4	1	2	32	Regular	-
Esplora	ATmega32u4	5 V/7-12 V	16Mhz	-	-	1	2.5	32	Micro	-
ArduinoBT	ATmega328	5 V/2.5-12 V	16Mhz	6/0	14/6	1	2	32	-	1
Fio	ATmega328P	3.3 V/3.7-7 V	8 Mhz	8/0	14/6	1	2	32	Mini	1
Pro (168)	ATmega168	3.3 V/3.35-12 V	8 Mhz	6/0	14/6	0.512	1	16	-	1
Pro (328)	ATmega328	5 V/5-12 V	16Mhz	6/0	14/6	1	2	32	-	1
Pro Mini	ATmega168	3.3 V/3.35-12 V 5 V/5-12 V	8 Mhz 16 MHz	6/0	14/6	0.512	1	16	-	1
LilyPad	ATmega168V ATmega328V	2.7-5.5 V/2.7-5.5 V	8 Mhz	6/0	14/6	0.512	1	16	-	-
LilyPad USB	ATmega32u4	3.3 V/3.8-5V	8 Mhz	4/0	9/4	1	2.5	32	Micro	-
LilyPad Simple	ATmega328	2.7-5.5 V/2.7-5.5 V	8 Mhz	4/0	9/4	1	2	32	-	-
LilyPad SimpleSnap	ATmega328	2.7-5.5 V/2.7-5.5 V	8 Mhz	4/0	9/4	1	2	32	-	-
Yùn	ATmega32u4	5 V/5 V you should provide regulated 5V	16 MHz	7/0	20/7	1	2.5	32	Regular Micro	1
Tre	ATmega32u4		16 MHz	6/0	14/7 (5 V) 12/4 (3.3 V)	1	2.5	32

We might cover some Arduino models. To get start, you can check following models:

Arduino Uno, basic one with a replaceable chipset.
Arduino Mega 2560, provides a bunch of inputs and output.
Arduino LilyPad, wearable as clothes.
Arduino Nano, very small device.

For my series of tutorials unless told otherwise, I will use Arduino Uno and sometime Arduino Mega.

Reference

Arduino official site – http://arduino.cc/