01 GPIO||General Purpose Input Output.2016

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01-General Purpose Input/ Output

By : Mohamed Fawzy

Programming AVR Microcontrollers

© Mohamed F.A.B 2015

Lecture Notes:

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o Set Your Phone To Vibration Mode.

o Ask any time.

o During labs, Feel Free To Check Any Materials or

Internet.

o Slides are self content.

o Feel Free To Share This Materials With Your Friends.

o Work Hard For Achieving Most Benefits Of This Course.

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Don't Forget !!!!


Any Expert Was Once A Beginner

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Agenda.

Lesson (4):

ATMEGA32 Overview and Main Hardware

Connections.

Lesson (5):

GPIO (General Purpose Input Output) Module.


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Lesson (4) Topics.


Lesson (4):

ATMEGA32 Overview and Main Hardware Connections.

► Take a look in Datasheet.

► ATMEL Code Decoding.

► Main Hardware Connection.

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ATMEL Code Decoder (OLD).


AT-MEGA-8L-8PI

ATMEL

Family

Flash Size

Low Power(2.7V)

FOSC

PDIP

I:industerialC:comertialM:martial

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ATMEL Code Decoder (New).


AT-MEGA-32A-Px

ATMEL

Family

Flash Size

New Generation

PU:PDIPAU:SMD

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Main Hardware Connections.


RESET.

Power Pins (VCC,GND).

FOSC (XTAL1,XTAL2).

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Lesson (5)


Lesson (5):


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Lesson (5) Topics.


Lesson (5):


► GPIO in ATMEGA32.

► Control GPIO in ATMEGA32.

► Interfacing LED with MC.

► Interfacing Switch with MC.

► Project (1) Password.

► Project(2) The Game.

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ATMEGA32 GPIO.


o ATMEGA32 has 32 GPIO Pin.

o ATMEGA32 has PORTs (PORTA,PORTB,PORTC,PORTD).

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GPIO Characteristics in ATMEGA32.


o General Purpose Input Output (GPIO).

o Bi-directional I/O s with internal Pull Up

Resistors.

o Push Pull Outputs ( Source or Sink for current).

o GPIOs are Grouped Into Ports Of Up to 8 Pins.

o Each IO Pin Has Two Protection Diodes.

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I/O Equivalent Schematic.


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Control GPIO in ATMEGA32.


o DDRx To define if PIN or PORT is Input or Output.

o PINxTo receive output from out world.

o PORTxTo set value to be out from MC.

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Example (PORTA)-Datasheet Page 66


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Accessing I/O ports in CodeVision.


Controlling All PORT Pins:

Controlling Single Pin:

DDRC=0xFF;

//configure all PORTC as output (Hexadecimal Format).

DDRC=0b11111111;

//configure all PORTC as output (Binary Format).

DDRC=255;

//configure all PORTC as output (Decimal Format).

PORTC=0xF0;

PORTC=0b11110000;

PORTC=240;

DDRC.0=1;

//configure PORTC0 pin as output.

DDRC.1=0;

//configure PORTC1 pin as input.

PORTC.0=1;

//outing logic 1 (5V) on PORTC0 Pin.

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Interfacing LEDs with µC


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LED (Light Emitting Diode) .


o LED stands for Light Emitting Diode.

o LED has a polarity.(Anode & Cathode).

o LED need almost 10mA and 3V to work.

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Source & Sink Current.


Source Current. Sink Current

NOTES:

Source Current is better.

At high current:

Source: MC will hung up.

Sink: MC will be damaged.

See Datasheet page 297 (Electrical Characteristics).

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Interfacing LED with µC.


Now, We need to design a circuit of

interfacing LED with µC.

I led=10mA.

Vled= 3V.

V mc= 5V.

𝑅 =5−3

10𝑚𝐴=

2

10𝑚𝐴=200Ω.

Typical R Value=220Ω or 330 Ω.

We need to connect LED to PORTC0 and blinking it every 500 ms.

Exercise (1).

Don't forget to include delay library header file.#include <delay.h>

NOTE

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Interfacing Buttons with µC


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Pull Up and Pull Down Resistors.


Pull Up Resistor. Pull Down Resistor.

Why use Pull Up and Pull Down.

Why use R1?

R1 between 4.7K Ω and 10K Ω.

Why R1 10K Ω.

ATMEGA32 Has an Internal Pull Up Resistor.

NOTE

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Switch bounce and de-bounce.


o Switch De-Bounce

Software Solution.

Hardware Solution (RC Filter and schmitt Trigger).

We need to connect LED to PORTC0 and control it

using switch.

Exercise (2).

Predicted

True

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Switch Key Click Vs. Key Press.


EX:If (sw is pressed)

{

delay_ms (250); //debounce delay & press wait

//statements

}

o Key Click: A Function For This Button Doesn't Be Executed Until You

Release Your Hand From The Button.

EX:If (sw is pressed)

{

delay_ms (10); //debounce delay

//statements

while (sw is pressed); //still press do nothing

}

Key Press: A Function Of This Key will be executed as soon as you press the

Button.

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Projects.


We need to connect LED on PORTC0 and three

buttons (PORTC1,PORTC2,PORTC3)

When I press button1 one time,button2 two times

and button3 three times, LED on PORTC0 turn ON

for 0.5 second.

Project (1) Password.

We need to connect 8LEDs on PORTC , 8LEDs on

PORTB and two buttons (PORTA0 and PORTA1)

[the two players].

Every press on button1 (PORTA0) increment PORTC by 1 and Every press on button2 (PORTA1)

increment PORTB by 1 and first one reach 255 is the winner.

Project (2) The Game.

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Motivation.


We need to connect 5 LEDs to PORTD0 and Flashing it.

Exercise (3).

Let's Know what is Wrong Next Lecture.

NOTE

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Questions:


Thank You All

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[email protected]

01006032792

[email protected]


Date post:	14-Feb-2017
Category:	Engineering
Upload:	mohamed-fawzy
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01 GPIO||General Purpose Input Output.2016

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