Arduino based applications part 2

Liquid Crystal Display
(LCD)
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LCDs are available to display characters, arbitrary images (as in
a general-purpose computer display) or fixed images which
can be displayed or hidden, such as preset words, digits, and
7-segment displays as in a digital clock. They use the same
basic technology, except that arbitrary images are made up of
a large number of small pixels, while other displays have larger
elements.
Some types of LCDs:
1- Character LCD
2- Graphic LCD
3- Graphic LCD with Touch Panel

1- Character LCD
Character LCDs are ideal for displaying text. They can also be
configured to display small icons but the icons must be only
5x7 pixels (very small!).
If you look closely to your LCD you can see little rectangles
where the characters are displayed. Each rectangle is a grid of
pixels.
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2- Graphic LCD
The graphical LCD has one big grid of pixels (in this case
128x64 of them) - It can display text but its best at displaying
images. Graphical LCDs tend to be larger, more expensive,
difficult to use and need many more pins because of the
complexity added.
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3- Graphic LCD with Touch Panel
This type of LCD also has one big grid of pixels and in addition
to that, it can be used as input screen too, so the user can
select some functionality to be done by using the touch
feature of this LCD.
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Character LCD
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:Character LCD pin out
The LCDs have a parallel interface, meaning that the microcontroller has to
manipulate several interface pins at once to control the display. The
interface consists of the following pins:

• Register Select (RS) pin:
It controls where in the LCD's memory you're writing data to.
You can select either the data register, which holds what goes
on the screen, or an instruction register, which is where the
LCD's controller looks for instructions on what to do next.
• Read/Write (R/W) pin:
It selects reading mode or writing mode.
• Enable (E) pin:
It enables writing to the registers
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• Display Contrast (Vo) pin:
To control the display contrast.
• Power supply (+5V and GND) pins:
To power the LCD.
• LED Backlight (BKlt+ and BKlt-) pins:
To turn on and off the LED backlight.
• 8 Data (D0 -D7) pins:
The states of these pins (high or low) are the bits that you're
writing to a register when you write, or the values you're
reading when you read
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The process of controlling the display involves putting the data of
what you want to display into the data registers, then putting
instructions in the instruction register.
The LiquidCrystal Library simplifies this for you so you don't need
to know the low-level instructions.
The Liquid Crystal Library allows you to control LCD displays that
are compatible with the Hitachi HD44780 driver.The Hitachi-
compatible LCDs can be controlled in two modes:
4-bit or 8-bit. The 4-bit mode requires seven I/O pins from the
Arduino, while the 8-bit mode requires 11 pins. For displaying
text on the screen, you can do most everything in 4-bit mode.

Example:
The following example shows how to control a 2x16 LCD in 4-bit
mode.
Hardware Requirement
To build such application, you need the following components:
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• Arduino Uno
• USB cable
• 16×2 Character LCD
• Jumper wires

11
LCD to Arduino Uno Connections:

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#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd( 12 , 11 , 5 , 4 , 3 , 2 );
int backlightPin = 10;
int ContrastPin = 6;
void setup( )
{
pinMode( backlightPin , OUTPUT );
analogWrite( backlightPin , 100 );
pinMode(ContrastPin,OUTPUT);
analogWrite( ContrastPin , 255 );

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// set up the LCD's number of columns and rows:
lcd.begin( 16, 2 );
// set the cursor to column 0, row 0
lcd.setCursor( 0 , 0 );
// Print a message to the LCD.
lcd.print( "Hi" );
lcd.setCursor( 0 , 1 );
// Print a message to the LCD.
lcd.print( "CS Students... " );
}
void loop( )
{
}

Speaker
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A speaker, buzzer, or beeper is an audio signaling device
(making beeps, tones and alerts). Typical uses of this device
include alarm devices, timers, and confirmation of user input
such as a mouse click or keystroke.
To build such application, you need
the following components:
• Arduino Uno
• USB cable
•Breadboard
• Speaker
• Jumper wires

Inter the Code
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int speakerPin =6;
int numTones = 10;
int tones[ ] = {261, 277, 294, 311, 330, 349, 370, 392, 415, 440};
void setup( )
{
for ( int i = 0; i < numTones; i++ )
{
tone( speakerPin, tones[ i ] );
delay( 500 );
}
noTone( speakerPin );
}
void loop( )
{
}

Speaker
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To play a note of a particular pitch, you specify the frequency.
The different frequencies for each note are kept in an array.
An array is like a list. So, a scale can be played by playing each
of the notes in the list in turn. The 'for' loop will count from 0
to 9 using the variable 'i'. To get the frequency of the note to
play at each step, we use 'tone[i]'. This means, the value in
the 'tones' array at position 'i'. So, for example, 'tones[0]' is
261, 'tones[1]' is 277 etc.
The Arduino command 'tone' takes two parameters, the first
is the pin to play the tone on and the second is the frequency
of the tone to play.

Speaker
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When all the notes have been played, the 'noTone' command
stops that pin playing any tone. We could have put the tone
playing code into 'loop' rather than 'setup', but frankly the
same scale being played over and over again gets a bit
tiresome. So in this case, 'loop' is empty. To play the tune
again, just press the reset button.
Sound waves are vibrations in the air pressure. The speed of
the vibrations (cycles per second or Hertz) is what makes the
pitch of the sound. The higher the frequency of the vibration,
the higher the pitch.

Speaker
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To hear the output, we need to attach something that will
convert the electrical signal into sound waves. This can be done
with a loudspeaker or as we have used here a piezo sounder.
Piezo sounders use a special crystal that expands and contracts
as an electrical signal passes through it. This will generate a tone
that we can hear.

Arduino based applications part 2

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