AVR_Course_Day4 introduction to microcontroller

Introduction to
Microcontroller
Eng:Mohamed Loay Ali Eng:Khaled Khamis
1

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 Controllers
1)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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2) MCU:
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2) 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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2) MCU:
Example Microcontroller System
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CISC
Complex 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
2) MCU(Instruction Set):
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RISC
Reduced 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.
2) MCU (Instruction Set):
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RISC Vs CISC
2) 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 instruction
memory is usually a relatively large external memory (at
least with general CPUs)
2) MCU(Memory Types):
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2) 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)
2. Can be erased using Electricity (from PC).
3. Needs short time to be erased (few milliseconds).
Flash EEPROM
2. Can be erased using Electricity (from PC).
3. Needs very short time to be erased (few microseconds).
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2) MCU (Memories Located in MCUS):
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2) 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/p
PORTA: determine if the port generate logic 1 or 0.
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2) MCU (Comparison between Different types of MCUs):
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3)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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3)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 Compilers
1) 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,SuperH
System/390 / zSeriesVAX,x86-64
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Types of Compilers
2)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 - 4MHz@1.8 - 5.5V,
 0 - 10MHz@2.7 - 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 VCC
AREF: 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 input
output source capability: 20mA
Special Functions of the Ports available as configured using the SFRs:
Port D: Uart, external Interrupts, Analog Comparator
Port B: External Oscillator/Crystal, SPI
Port C: A/D converters, TWI
AVR Datasheet
31

AVR Block Diagram (Atmega328)
AVR Datasheet
32

AVR Datasheet
AVR Circuit (Atmega328)
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AVR Datasheet
AVR Circuit Components (Atmega328)
1) Atemga328.
2) Crystal Oscillator 16 MHz
3) 2 Capacitor 22 pf.
4) 10 Kilo ohm Resistor.
5) Press Switch.
6) Power Supply 5V
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AVR Datasheet
AVR Clock Systems
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● Clock Muliplexer selects the clock
source according to FUSE settings
● Clock Control Unit distributes clocks
clocks can be halted to reduce power
consumption
● 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 Datasheet
AVR Clock Systems(options)
36

● 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 Datasheet
AVR Clock Systems(Fuse Bits)
37

AVR Datasheet
AVR Clock Systems(Using External Crystal)
38

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 Register
2) PORTx – Pin Output Register
3) PINx – Pin Input Register
where x = GPIO port name (A, B, C or D)
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40

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PORTx 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 output
PORTD = 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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PINx Register:
 The PINx register gets the reading from the input pins of the MCU.
 The register goes as follows:
Examples of setting the input
DDRC = 0b10110001;
PINC = 0b01001011;
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Writing First Code in AVR
See the Appendix For information about Atmel Studio
Also, 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. Khazama
2. Extreme Burner
3. AVR Burn – O - Mat
Transfer the Program to AVR:
46

Switch Debouncing
The Problem:
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Switch Debouncing
The Solution by Hardware:
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AVR_Course_Day4 introduction to microcontroller

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