Training PPT on AVR MICROCONTROLLER

1. AVR Microcontrollers

What is a microcontroller?
− microprocessor
− Read-write memory
− Flash memory
− EEPROM
− Input/Output Control
− Peripheral Devices (AD/DA)

Billions sold per year, most processors

Emphasis is on cost. (pennies)

Alternative/paired to ASIC/DSP

Emphasis on power consumption

2. ATMega32 Specifications

Low-Power 8-bit AVR Microcontroller

Modified Harvard Architecture

Around $4 individual, $2.50 in Volume

32 8-bit general-purpose registers

131 Instructions, Multi-cycle Implementation
− Most are single-cycle
− 2-cycle multiply, 2-cycle memory access
− Thus up to 1MIPS/MHz

20MHz, up to 20MIPS

16KB self-programmable Flash

512 Bytes EEPROM

1KB SRAM

3. Uses

Consumer electronics

Appliances

Automotive

Electrical/Heating

Computers / Hard Drives

Hobbyist projects!
− Installation art
− Musical instruments
− Home automation
− Audio Distribution
− Web Server!!
− MANY MORE!!

4. Manufacturers

Intel, Freescale, Microchip (PIC), TI, Zilog

Atmel AVR
− Many Types, tinyAT, megaAT, automotive
− Lighting, LCD
− Share unified platform
− Different #s of I/O control
− Built-in Pull-up resistors
− Ethernet, Serial Data, Auxiliary Power, USB
− Analog I/O, Packaging, Interrupts, Math, JTAG
− Get the right amount of memory for the job

5. Development Platforms

Everything Needed, All-In-One

Arduino / Diecimila
− ATMega8 / ATMega168 based
− Open source, multiplatform IDE
− Cheap ($33 assembled!)
− Great Online Community
− USB, power, protoshield available, breadboard,
LEDs

Parallax (PIC)

PICAXE (PIC)

ArmExpress

Many Others

6. Cheaper

A Transistor Saved is a Transistor Earned

No Lack Floating Point

Non-Pipeline

No cache

Limited Math / Branching

Very Slow (1 to 32MHz)

Very Little Memory (64bytes to 256KB)

From under a dollar to $20 for advanced
− Cheaper in volume
− Important for large product runs

7. AVR History

Conceived by two students at Norwegian
Institute of Technology (NTH)
− Alf-Egil Bogen and Vegard Wollan

Originally Known as μRISC (Micro RISC)

Sold to Atmel, continued working under
Atmel Norway subsidiary

AVR supposedly not acronym
− May mean Advanced Virtual RISC

Beauty in simplicity
− Can wrap mind around entire CPU

8. ATMega32 IO

6 PWM Shared Input/Outputs (Analog)

8 digital input/outputs

SPI-serial, 2-wire serial, ISP, others
− Monitoring, debugging, programming, power

USART serial interface
− (interfaces with USB on Arduino)

11. Instruction Set

Mostly unified across all AVR
− With exceptions for feature differences

32 or 16 bit instructions

8-bit fields, vary depending on instructions

I/O manipulation treated in similar fashion to
registers
− Allows for clean and simple usage

Parallel Instruction Fetch

Uses Skip instead of Branches

Use software libraries for more complex
functionality (divide)

12. Registers

32 general purpose registers

Addressable as first 32 memory addresses

4 Different Simultaneous Access Schemes

X, Y, Z registers for indirect memory
− Dual-purpose, 16 bit
− 26/27, 28/29, 30/31

200+ I/O, settings, timers, interrupts registers

Overflow at 256 / 65K!

13. Registers

14. Memories

3 different memories
− SRAM
− Flash
− EEPROM

Direct/Indirect Addressing (5 modes total)

Flash is divided into two 8KB sections
− Independently addressable

Flash has reserved Bootloader section for
software security

15. Additional Functionality

Registers for serial access

Interrupts

External Interrupts

Power Management

Timers

Analog Comparators

Other Goodies

All handled via special registers
− Some settings via bit-flags

16. Compilers

Meant for Assembly Programming
− Many environments available

BASIC and FORTRAN compilers available

Open Source Tools and Compilers

avr-GCC for C/C++ support

AVR Studio Assembler / Simulator
− Supported, official, Windows-only IDE

17. Operating System?

No common operating systems available

None would work!

EEPROM Bootloader / Initializer

Real-Time Operating Systems

Commercial Systems:
− Salvo
− AVRX
− NutOS
− Proc

18. FreeRTOS

Free and Open Source Operating System
− Portable across many platforms
− Royalty Free

1-2KB storage

50-100Bytes Memory

Can spawn off “tasks”
− Guaranteed timings, simple

“Coroutines”
− Less memory, more complex, coexist, portable

Commercial Sister Projects

19. Loading

EEPROM burner / custom Programmer

ISP-interface
− Serial / Parallel Programming (AVRdude)

USB tty support

Most IDE's available will make this job easy

20. Future

Smaller, Better, Faster, Cheaper

Many new products become possible
− Children's toys
− Ubiquitous Computing
− Physical Computing

Becoming very popular among Hobbyists

Great introduction for CS people into EE-land

21. A/D CONVERTER
An Analog-to-digital
converter (abbreviated ADC, A/D or A to D) is a device
that converts a continuous physical quantity (usually
voltage) to a digital number that represents the quantity's
amplitude. The conversion involves quantization of the
input, so it necessarily introduces a small amount of
error. Instead of doing a single conversion, an ADC often
performs the conversions (“samples" the input)
periodically. The result is a sequence of digital values
that have converted a continuous-time and continuous-
amplitude analog signal to a discrete time and discrete-
amplitude digital signal.