1.Introduction to AVR.pdf

Introduction to AVR Microcontroller
by:
Eng. Mohamed Tarek.
© 2014 by Eng. Mohamed Tarek. 1

Micro-controller vs. Micro-processor
 Micro-controller
• Basically a microcontroller can be described as
a computer on a chip. a single chip containing
a CPU, non-volatile memory (RAM), volatile
memory(ROM), a timer and an I/O control unit.
• A microcontroller apart from the above mentioned
components usually also include serial
communication capabilities, interrupt controls and
analog I/O capabilities.
• Used for a few dedicated functions determined by
the system designer.

Many IC’s into one IC

 Microcontrollers don’t work alone in the circuit it must
interfaces with other on chip devices like Sensors,
Switches, Leds, LCD, Keypad and DC Motor
 Microcontroller can accept inputs from some
components and provide outputs to other components
within any given system.
 Differences in requirements, make the manufacturers
produce different microcontrollers with different
memory sizes, number of I/O lines and number of
integrated peripheral devices. Other wise they are all
similar to use.

 Micro-processor
• Just a CPU has to add externally memory, clock,
input/output interfaces, timer and all other
needed peripheral. This is the reason
a microprocessor has so many pins.
• The difference between a microcontroller and
a microprocessor is that the microprocessor is
a general purpose computer while a microcontroller
is a computer dedicated to one or just a few tasks.

Micro-Controller Components
 Processor:
The processor refers to the Central Processing Unit (CPU) of the
microcontroller. It contains the Arithmetic Logic Unit (ALU), Control
Unit, Instruction Decoder and some Special Registers (Stack
Pointer, Status Register, Program Counter, etc.).
 Volatile Memory(RAM):
This is memory used by the microcontroller for temporary data
storage, system setup and peripherals configurations. Memory in
this category includes SRAM and DRAM. AVR microcontrollers
utilize SRAM.
 Non-Volatile Memory:
This is memory used by the microcontroller to store programs. Data
can also be stored in this memory but the access time is much
slower than that of RAM. Memory in this category includes ROM,
PROM, EPROM, EEPROM and FLASH. The AVR microcontrollers
utilize Flash for program storage, some AVR controllers contains a
bit of EEPROM as well.

Micro-Controller Components(Cont.)
 Timer Module:
Most microcontrollers have at least one timer/counter peripheral.
Timer/Counter modules are used to perform timing or counting
operations in the controller. These include time stamping, measuring
intervals, counting events, etc.
 Interrupt Module:
Interrupts enable the microcontroller to monitor certain events in the
background while executing and application program and react to
the event if necessary pausing the original program. This is all
coordinated by the interrupt module.
 Digital I/O Module:
This module allows digital/logic communication with the
microcontroller and the external world. Communication signals are
that of TTL or CMOS logic.

Micro-Controller Components(Cont.)
 Analog I/O Modules:
These modules are use to input/output analog information from/to
the external world. Analog modules include Analog Comparators
and Analog-to-Digital Converters.
 Serial Modules:
These modules are used for serial communication with the external
world. An example is the USART peripheral which utilizes the
RS232 standard.

Manufacturers of Micro-controllers
 Atmel Corp. :
Manufacturers of the popular AVR series of microcontrollers.
 Microchip Technology Inc. :
Manufacturers of the PIC series of microcontrollers.
 Texas Instruments Inc. :
One of the world's largest semiconductor companies..
 Renesas Technology Corp. :
A joint merger of Hitachi and Mitsubishi product lines.
 Motorola company:
Manufacturers of the FreeScale series of microcontrollers

AVR History
 AVR was developed in the year 1996 by Atmel
Corporation.
 The architecture of AVR was developed by Alf-Egil
Bogen and Vegard Wollan.
 AVR derives its name from its developers and stands for
Alf-Egil Bogen Vegard Wollan RISC microcontroller.
 Also known as Advanced Virtual RISC.
 The first microcontroller to hit the commercial market
was AT90S1200 in the year 1997.

AVR Micro-controllers Categories
 1.TinyAVR :
• Less memory
• small size
• suitable only for simpler applications.

AVR Micro-controllers Categories(Cont.)
 2.MegaAVR :
• These are the most popular ones.
• having good amount of memory (up to 256 KB) higher
number of inbuilt peripherals
• suitable for moderate to complex applications.

 3.XmegaAVR :
• Used commercially for complex applications, which
require large program memory and high speed.

What’s special about AVR? (Cont.)
 AVR micro-controllers are fast executes most of the
instructions in single execution cycle.
 AVRs are about 4 times faster than PICs.
 They consume less power and can be operated in
different power saving modes.
 Free IDE.
 Available in Egyptian market.

 comparison between the three most commonly used
families of microcontrollers:

 8-bit Micro-controllers

What’s special about AVR?(Cont.)
 AVR follows Harvard Architecture
• the processor is equipped with separate memories and buses for
Program and the Data information. Here while an instruction is
being executed, the next instruction is pre-fetched from the
program memory.

Atmega16
 Naming Convention

Flavors of Atmega16
 There are two flavors for Atmega16 microcontroller:
1. Atmega16: Operating frequency range is 0 – 16 MHz.
2. Atmega16L: Operating frequency range is 0 – 8 MHz.
If we are using a crystal of 8 MHz = 8 x 106 Hertz =
8 Million cycles, then AVR can execute 8 million
instructions.

Atmega16 Architecture

Atmega16 Architecture(Cont.)
 General Purpose Registers:
Atmega16 is equipped with 32 general purpose registers
which are coupled directly with the Arithmetic Logical
Unit (ALU) of CPU.
 I/O Ports:
Atmega16 has four (PORTA, PORTB, PORTC and
PORTD) 8-bit input-output ports.
 ADC Interface:
Atmega16 is equipped with an 8 channel ADC with a
resolution of 10-bits.

 Timers/Counters:
Atmega16 consists of two 8-bit and one 16-bit
timer/counter.
 Watchdog Timer:
present with internal oscillator. Watchdog timer
continuously monitors and resets the controller if the
code gets stuck at any execution action for more than a
defined time interval.
 Interrupt:
consists of 21 interrupt sources out of which four are
external. The remaining are internal interrupts which
support the peripherals like USART, ADC, Timers etc.

 USART:
Universal Synchronous and Asynchronous Receiver
and Transmitter interface is available for interfacing
with external device capable of communicating serially
(data transmission bit by bit).
 SPI:
Serial Peripheral interface port is used for serial
communication between two devices on a common clock
source.
 ISP(In System Programmable ):
Flash Memory which can be programmed without
removing the IC from the circuit.

 Internal Calibrated Oscillator:
• Atmega16 is equipped with an internal oscillator for
driving its clock. By default Atmega16 is set to
operate at internal calibrated oscillator of 1 Mhz.
• The maximum frequency of internal oscillator is 8Mhz.
• ATmega16 can be operated using an external crystal
oscillator with a maximum frequency of 16MHz

 Memory: Atmega16 consist of three different
memory sections:
• Program flash EEPROM memory: Atmega16 is
available with 16KB of in system programmable Flash
EEPROM.
• Byte Addressable EEPROM: Atmega16 has 512
bytes of EEPROM.
• SRAM(data memory) :Atmega16 is equipped with
1KB of internal SRAM.
Note: A small portion of SRAM is set aside for general
purpose registers used by CPU and some for the
peripheral subsystems of the microcontroller.

Atmega16 pins

Active Low Reset circuit
R= 4.7KΩ
C= 0.1µf or 100nf

Internal Calibrated RC Oscillator

External Crystal Oscillator
C1 = C2 = 22pf

External Crystal Oscillator(Cont.)

External Crystal Oscillator(Cont.)
 Example: configure the µC to deal with 16Mhz Crystal
• CKSEL3  1
• CKSEL2  1
• CKSEL1  1
• CKSEL0  1
• CKOPT  0

How to program AVR Microcontroller using ISP

Contact Details
Eng. Mohamed Tarek.
Embedded Software Engineer
Tel: 01115154316
mtarek.2013@gmail.com

1.Introduction to AVR.pdf

More Related Content

What's hot (20)

Similar to 1.Introduction to AVR.pdf (20)

More from MostafaKhaled78 (11)

Recently uploaded (20)

1.Introduction to AVR.pdf