avr_course_day4 introduction to microcontroller

Introduction to Microcontroller

Eng:Mohamed Loay Ali Eng:Khaled Khamis

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Contents

• Types of Controllers.

• Types of Compilers.

• AVR DataSheet.

• AVR input/output Configuration.

• Writing First Code in AVR.

• Transfer First Program to AVR.

• Switch Debouncing (Case Study).


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Types of Controllers1)Microprocessor based Systems:Industrial PC, u computer , mainframes


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Microprocessor (CPU).


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Microprocessor Architecture:


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The MPU communicates with Memory and I/O using the System Bus

Address bus Unidirectional

Memory and I/O Addresses

Data bus Bidirectional

Transfers Binary Data and Instructions

Control lines Read and Write timing signals


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Example Microprocessor System



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Types of Controllers2) MCU:


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Types of Controllers2) MCU:

System hardware

Discrete components Microprocessor, Memory, and I/O

Components connected by buses Address, Data, and Control

System software

A group of programs that monitors the functions of the entire system


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Types of Controllers2) MCU:Example Microcontroller System


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CISCComplex Instruction Set Computer “High level" Instruction Set Executes several “low level operations” Ex: load, arithmetic operation, memory store

Features of CISC: Initially made to do very complex instructions. Instructions can operate directly on memory Small number of general purpose registers Instructions take multiple clocks to execute Few lines of code per operation

Types of Controllers2) MCU(Instruction Set):


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RISCReduced Instruction Set Computer RISC is a CPU design that recognizes only a limited number of

instructions Simple instructions Instructions are executed quickly

Features of RISC: Found to be more efficient in computing very complex instructions by using many of very short and simple instructions. Executes a series of simple instruction instead of a complex

instruction Instructions are executed within one clock cycle. Incorporates a large number of general registers for arithmetic operations to avoid storing variables on a stack in memory. Only the load and store instructions operate directly onto memory.

Types of Controllers2) MCU (Instruction Set):


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RISC Vs CISC

Types of Controllers2) MCU (Instruction Set):


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Register File: A (usually) relatively small memory embedded on the CPU. It is used as a scratchpad for temporary storage of values the CPU is working with you could call it the CPU’s short term memory.

Data Memory: For longer term storage, generic CPUs usually employ an external memory which is much larger than the register file. Data that is stored there may be short-lived, but may also be valid for as long as the CPU is running

Instruction Memory: Like the data memory, the instructionmemory is usually a relatively large external memory (atleast with general CPUs)

Types of Controllers2) MCU(Memory Types):


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Types of Controllers2) MCU (Memory Types):


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Volatile Memory RAM (Random access memory):1)SRAM (Static RAM):

SRAM consists of flip flops (Electronic component that can store data). Expensive. Exists in small sizes.

DRAM consists of capacitors (Electronic component that can store data by charging and discharging).

Needs refresh circuit to keep the capacitors charged (when holding ‘1’).

Inexpensive. Exists in larger sizes.

2)DRAM (Dynamic RAM):



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Non Volatile memories ROM (Read only memory):

PROM (Programmable ROM )1- One time programmable (OTP).2- Used to protect the data that can’t be erased and rewritten.

EPROM (Erasable PROM)1. Multi-time programmable.2. Can be erased using UV (Ultraviolet) rays from the sun.3. Needs long time to be erased (about 20 minutes).



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EEPROM (Electrically EPROM)1. Multi-time programmable.2. Can be erased using Electricity (from PC).3. Needs short time to be erased (few milliseconds).

Flash EEPROM1. Multi-time programmable.2. Can be erased using Electricity (from PC).3. Needs very short time to be erased (few microseconds).



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Types of Controllers2) MCU (Memories Located in MCUS):


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Types of Controllers2) MCU (Registers in MCUS): The memory in which the microcontroller stored data during the execution of the program.Classified into two types:

1. General purpose registers. There are 30 General purpose registers in microcontrollers rages from R1 to

R31. Any variables are declared in the program are stored in this registers, like the

variables of mathematical operations.

2. Special function registers.• Special function registers are registers defined by the manufacturer of the

microcontroller itself to give an access to the features of microcontroller like Timer, SPI, UART, ADC, IO ports and external interrupt modules.

• Ex:DDRA: determine the state of this port I/p or O/pPORTA: determine if the port generate logic 1 or 0.


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Types of Controllers2) MCU (Comparison between Different types of MCUs):


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Types of Controllers3)DSP (Digital Signal Processor):

Advantages of DSP Conventional DSP devices are well-suited to a wide range of

applications requiring mathematical processing power. This arises from the high-speed DSP cores of the devices and a number

of architectural features. DSPs typically support a single-cycle multiply-accumulate function,

crucial to efficient DSP algorithm implementations.

Disadvantages of DSP: Not Suitable for application requiring Computaional processing power and

interrupts. Doesn’t include automotive communication module (CAN,LIN). Very Expensive Compared with MCU.


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Types of Controllers3)DSC (Digital Signal Controller):

DSC series of devices specifically addresses two main application requirement areas.

First, computational requirements associated with complex control algorithms are met by a high-speed core, capable of executing up to 40 million multiply-accumulate operations per second.

Second, control system interface requirements are met by a rich integrated peripheral set, including PWM capability, analog-to-digital conversion, bit I/O, and multiple serial interfaces.

Examples:1) The 56F800 DSC series (Free Scale).2)The Lm4f123 DSC (Texas Instruments)


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Types of Compilers1) Atemel Studio (GCC Compiler):

The GNU Compiler Collection (GCC) is a compiler system produced by the GNU Project supporting various programming languages.GCC is a key component of the GNU toolchain.

The Free Software Foundation (FSF) distributes GCC under the GNU General Public License (GNU GPL)

GCC target processor families as of version 4.3 include:Alpha,ARM,AVR,Blackfin,H8/300,HC12,IA-32 (x86),IA-64,MIPS,Motorola 68000,PA-RISC,PDP-11,PowerPC,R8C / M16C / M32C,SPARC,SPU,SuperHSystem/390 / zSeriesVAX,x86-64


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Types of Compilers2)CodeVision:

Is the only integrated development environment on the market that features an automatic program generator for AVR Family.

It targets only the AVR Processor.


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ATmega8 - RISC Architecture

● 131 Instructions – Most Single-clock Cycle Execution● 32 x 8 General Purpose Working Registers● 64 x 8 Special Function Registers (I/O Registers)● Up to 16 MIPS Throughput at 20 MHz● On-chip 2-cycle Multiplier

Nonvolatile Program and Data Memories

● 4/8/16/32K Bytes of In-System Self-Programmable Flash 10,000 Write/Erase Cycles

● Optional Boot Code Section with Independent Lock Bits● 256/512/1 Bytes EEPROM (100,000 Write/Erase Cycles)● 1K Byte Internal SRAM● Programming Lock for Software Security

AVR Datasheet


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Peripheral Features

● Two 8-bit Timer/Counters● One 16-bit Timer/Counter with Capture Mode● Real Time Counter with Separate Oscillator● 6 PWM Channels● 8-channel ADC with 10 resp 8 Bit resolution (TQFP: 8 channels)● Two-wire Serial Interface (TWI)● Programmable Serial USART● Master/Slave SPI Serial Interface● Programmable Watchdog Timer with On-chip Oscillator● On-chip Analog Comparator

AVR Datasheet


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Special Microcontroller Features

● Programmable Brown-out Detection● Internal Calibrated RC Oscillator● External and Internal Interrupt Sources● 6 Sleep Modes

I/O and Packages

● 23 Programmable I/O Lines● 28-lead PDIP, 32-lead TQFP, and 32-pad MLF

AVR Datasheet


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Operating Voltages

1.8v to 5.5v

Speed Grades 0 - [email protected] - 5.5V, 0 - [email protected] - 5.5.V, 0 - 20MHz @ 4.5 - 5.5V

Power Consumption at 4 Mhz, 3V, 25°C● Active: 0.2 mA● Idle Mode: 0.1uA● Power-down Mode: 0.1 μA

AVR Datasheet


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AVR Pin Configuration (Atmega328)

AVR Datasheet


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Pin and Port Overview:

GND: Ground (0V)VCC: Digital Supply Voltage (2,7 – 5,5V)AVCC: Analog Supply Voltage

connect to low-pass filtered VCCAREF: Analog Reference Voltage, usually AVCC

/ Reset: Low level on this pin will generate a reset

Port B, Port C, Port D: General Purpose 8 Bit bidirectional I/O - Ports, optional internal pullup-resistors when configured as inputoutput source capability: 20mA

Special Functions of the Ports available as configured using the SFRs:

Port D: Uart, external Interrupts, Analog ComparatorPort B: External Oscillator/Crystal, SPIPort C: A/D converters, TWI

AVR Datasheet


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AVR Block Diagram (Atmega328)AVR Datasheet


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AVR DatasheetAVR Circuit (Atmega328)


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AVR DatasheetAVR Circuit Components (Atmega328)

1) Atemga328.2) Crystal Oscillator 16 MHz3) 2 Capacitor 22 pf.4) 10 Kilo ohm Resistor.5) Press Switch.6) Power Supply 5V


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AVR DatasheetAVR Clock Systems


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● Clock Muliplexer selects the clock source according to FUSE settings

● Clock Control Unit distributes clocksclocks can be halted to reduce powerconsumption

● CPU Clock: CPU, ALU, GPRs

● I/O Clock: Ports, Timers, SPI, UART

●ADC Clock: seperate cock for ADC noise reduction in sleep mode

●Asynchronous Timer Clock: external 32kHz Crystal for realtime clock, keeps timer module running during sleep mode

AVR DatasheetAVR Clock Systems(options)


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● The four CKSEL Bits of the FUSE – Byte select the main Clock Source

● The startup time to stabilize power supply and oscillator can be changed with the SUT fuses

● The device is shipped with internal RC oscillator at 8.0MHz and with the fuse CKDIV8 programmed, resulting in 1.0MHz system clock.

AVR DatasheetAVR Clock Systems(Fuse Bits)


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AVR DatasheetAVR Clock Systems(Using External Crystal)


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AVR Input/ Output Configuration

The following registers are related to the various port operations that we can perform with the GPIO pins.1) DDRx – Data Direction Register2) PORTx – Pin Output Register3) PINx – Pin Input Registerwhere x = GPIO port name (A, B, C or D)


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AVR Input/ Output ConfigurationPORTx Register:

The PORTx register determines whether the output should be HIGH or LOW of the pins.

DDRx initializes the port shown in the following figure.

Examples of setting the outputPORTD = 0b01001001;PORTD = 0x49; //suitable to define all pins of the port.PORTD = (1 << 0)|(1 << 3)|(1 << 6);PORTD|=(1<<PIND0) | (1<<PIND3) |(1<<PIND6);// using bitwise suitable to define one pin.


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AVR Input/ Output ConfigurationPINx Register:

The PINx register gets the reading from the input pins of the MCU. The register goes as follows:

Examples of setting the inputDDRC = 0b10110001;PINC = 0b01001011;


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Writing First Code in AVR

See the Appendix For information about Atmel StudioAlso, See the following Example (Led Blinking, Adding Button).


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Transfer First Program to AVR

The following programs are used to download the program (Hex file):1. Khazama2. Extreme Burner3. AVR Burn – O - Mat

Transfer the Program to AVR:


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Switch DebouncingThe Problem:


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Switch DebouncingThe Solution by Hardware:


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avr_course_day4 introduction to microcontroller

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