This is a microcontroller course for atmega328 (the chip used in Arduino Uno) explained very simply .

1. AVR Interfaces
Eng:Mohamed Loay Ali
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2. Contents
• 7 Segments
• LCD
• Keypad
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3. 7-Segements
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4. Liquid Crystal Display(LCD)
LCD Interfacing:
The LCD has the ability to display (Numbers, Characters and
graphics) so they are widely used in AVR real word applications.
LCD Description:
The following table shows the pin description of the LCD
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5. Liquid Crystal Display(LCD)
RS (Register Select):
When RS=0, this allow the user to send command such as (clear
screen, go home, blink cursor).
When RS=1, this allow the user to send data.
Enable:
It used to latch the information to the data pins, this done by send a
high to low pulse (of width of 450 ns) so the LCD latches the data
presented on the data pins.
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6. Liquid Crystal Display(LCD)
The Instruction Command for the LCD:
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7. Liquid Crystal Display(LCD)
Sending Commands and data to the LCD:
The following steps should be done to send the
command and data to the LCD:
1) Initialized the LCD.
2) Sending Commands to the LCD.
3) Sending data to the LCD.
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8. Liquid Crystal Display(LCD)
1)Initialized the LCD :
For example to initialize LCD [2 lines 5*7 matrix 8bit mode]
the following commands should be used:
1. 0x38 to select the type and mode of operation
2. 0x0E to display the cursor blinking.
3. 0x01 to clear the LCD display.
Note: After powering up the LCD a 15 ms should be waited
to send the commands.
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9. Liquid Crystal Display(LCD)
2)Sending Commands to the LCD :
To send commands to the LCD the following steps should be done:
1. RS=0, RW=0.
2. The command number should be put on the data pins (D0 to
D7).
3. A pulse (high to low) should be sent on the Enable pin.
After each command a delay of (100us) should be placed.
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10. Liquid Crystal Display(LCD)
3) Sending data to the LCD :
To send data to the LCD the following steps should be done:
RS=1, RW=0.
1. The data should be put on the data pins (D0 to D7).
2. A pulse (high to low) should be sent on the Enable pin.
After each data a delay of (100us) should be placed.
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11. Liquid Crystal Display(LCD)
Typical Connection of LCD(8bit mode) :
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12. Liquid Crystal Display(LCD)
Typical Connection of LCD(4bit mode) :
 Remember that there are a special pins on the AVR for example (ADC
pins, Interrupt pins, Communication pins).
 If one of those purposes is required in the application try to not connect
the LCD with those special pins required for the application.
 See 4bit and 8bit examples of LCD.
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13. KeyPad
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