®

~ DESIGNING USING THE AVR ~

®

~ LOW POWER DESIGN ~

5/7/2003 3

® AVR: Designed to Save Power

AVR uControllers Designed to Minimize Power Consumption

Power-Saving Features Single Cycle Instruction ExecutionSix Power-Saving Sleep ModesMinimum Amplitude OscillatorsAdvanced Power Management1.8 – 5.5 Volts Operation

5/7/2003 4

® General Rules for Low Power Design

Rule #1Use Low VCC and Low Frequency Clock, orUse High Frequency Clock and Sleep Modes

Rule #2Use RC Oscillator or Resonator

Lower Startup Time

Rule #3Disable Peripherals Not In Use

Rule #4Use AVR Devices Targeted for Low Power Consumption

tiny12/13tiny2313tiny28mega48/88/168mega162mega169

5/7/2003 5

® Other Power Saving Tips...

All 1.8 Volt AVR Devices (Except tiny12V) have a Dynamically Adjustable System Clock

Prescaler Programmed by Writing a Single Byte to the CLKPR Register

CLKPR = $00 System Clock = 8 MHzCLKPR = $04 System Clock = 512 kHzCLKPR = $08 System Clock = 32 kHz

Programming CLKDIV8 Fuse Adjusts System ClockCLKDIV8 = ‘1’ CLKPR = $00CLKDIV8 = ‘0’ CLKPR = $03

uController in Active ModeSpeed Critical Activities can Operate at Higher Frequencies, Otherwise Operate at Lower Frequencies

5/7/2003 6

® Optimizing Clock When Using Power Down Mode

Sleep periods should be as Long as PossibleActive periods should be as Short as Possible

Run at High FrequencyOscillator Startup Time should be as Short as Possible

Run on Internal RC if Possible

Vcc Min

Vcc

Time0 V

PowerON

Minimum Reset Delay

Vcc Rise Time

OscillatorStartup Time

Active ModeReset

SLEEP Wakeup

Wakeup

OscillatorStartup Time

ActiveIcc Sleep

5/7/2003 7

® AVR Oscillator Types

Additional timer oscillator on some devices

Long (16k-32k cycles)

High(10-50 ppm)

Medium (≈$0.20)

External low frequency (32kHz) crystal

Short(6 cycles)

Dependingon R and C

Low(≈$0.02)

External R/C oscillator

Short(6 cycles)

Depending on other circuits in the system

External clock

May be re-calibrated by application at any time

Short(6 cycles)

1% or better after

calibration

NONECalibrated Internal R/C oscillator

Medium (200-1k cycles)

Medium(0.5-1%)

Medium(≈$0.10)

External ceramic resonator

Long (16k cycles)

High(10-50 ppm)

High (≈$0.50)

External high frequency crystal

NotesStartuptime

AccuracyCost

5/7/2003 8

® Using Sleep Modes

Lower Average Power Consumption may be Acquired by Optimum Usage of Power Down Modes

Running a Device at High Speeds may Yield Lower Average Power Consumption due to Shorter ’On’ Time

Power

Time

Average Average

5/7/2003 9

® AVR Sleep ModesIdle Mode

CPU Stopped, Oscillators & Most I/O Modules ActiveAllows for Fast Wakeup from Sleep

ADC Noise Reduction ModeLike Idle Mode with Fewer I/O Modules Active

Power Down ModeCPU & Oscillator Stopped, Most Functions InactiveSlow Wakeup from Sleep – Oscillator must be Restarted

Power Save ModeLike Power Down Mode with 32 kHz Oscillator Running

Standby ModeLike Power Down Mode but Main Oscillator RunningAllows for Fast Wakeup from Sleep

Extended StandbyBoth Main Oscillator and 32 kHz Oscillator RunningAllows for Fast Wakeup from Sleep

5/7/2003 10

®

tiny2313V

mega162V

mega169V

mega88V

mega48V

mega168V

New 1.8 Volt AVR Devices

tiny11Ltiny12Ltiny13Ltiny15Ltiny2313Ltiny26Ltiny28L

mega48Lmega8Lmega8515Lmega8535Lmega88Lmega16Lmega162Lmega168Lmega169Lmega32Lmega64Lmega128L

tiny11tiny12tiny13tiny2313tiny26

mega48mega8mega8515mega8535mega88mega16mega162mega168mega169mega32mega64mega128

1.8 Volts

tiny12V

tiny13V

3.3 Volts 5 Volts1.8 - 5.5 V 2.7 - 5.5 V 4.0 - 5.5 V

®

~ HARDWARE DESIGN ~

Avoid the Most Common Design Flaws

5/7/2003 12

® Proper Decoupling of VCC

Insufficient Decoupling of VCC causes VCC to Drop when Switching I/O Lines

Place Decoupling Capacitors as Close to the AVR as Possible to Reduce Noise on VCC

5/7/2003 13

® Protecting the Oscillator

Crystals & Ceramic ResonatorsMount as Close to the AVR as PossibleUse Balanced Capacitive LoadIncreasing Capacitive Load, Increases Noise Immunity

Conversely, Decreasing Capacitive Load, Decreases Power Consumption

Always Surround the Circuit by Ground

5/7/2003 14

® Take Control of the Reset Signal

Internally RESET is Pulled HighTypical Value 100KExternal 4K7 Pull-Up Resistor Recommended

Enable Internal Brown-Out DetectorOr, Use External BOD Circuit (See Application Note AVR180)

5/7/2003 15

® AVR Hardware Design Hints

AVR040: EMC Design ConsiderationsVCC & GND ConnectionsReset Input

12 Volt Programming Voltage on RESET LineRESET is Asynchronous

AVR042: General Design ConsiderationsXTAL1 Capacitor Effects Higher Immunity Against BurstsXTAL2 Capacitor Effects Higher Current

5/7/2003 16

® Design Question

What is the minimum number of I/O pins required to control twelve LEDs, using no other components except current limiting resistors?

A) 3B) 4C) 6D) 12Using the Tri-State Capabilities of the I/O Pins, it is

possible to control up to Twelve LEDs with Four I/O Pins!

5/7/2003 17

® Design QuestionExample –

PB0 = ‘0’, PB1 = ‘1’, PB2/3 = HiZD10 = On, All Other LEDs Off

PB1

PB3

PB0

PB2

D10LED

D20LED

D01LED

D21LED

D31LED

D02LED

D12LED

D32LED

D03LED

D13LED

D23LED

R1270

R2270

R3270

R4270

D30LED

®

Efficient C-coding for AVR

Hints & Tricks to Reduce Code Size

5/7/2003 19

® Created for ‘C’

Instruction Set Designed for CExcellent 16 and 32-Bit SupportEfficient Bit Manipulation

Architecture Designed for CRegister File Reduces Data Handling OverheadLarge and Linear Memory MapMany Memory Pointers

The AVR Architecture and Instruction Set was Designed in Conjunction with IAR Systems:

Compiler Development Project Initiated before Architecture and Instruction Set FrozenCompiler Experts’ Advice Implemented in HardwarePotential HLL Bottlenecks Identified and Removed

5/7/2003 20

® AVR Benefits with ‘C’

Up to 50% Smaller Code Footprint Compared to Other Architectures

No Code Size Penalty Over Assembly, at a Fraction of the Development Time

Maintainable Code with Less Engineering Cost

Reusable Code for Upcoming Projects Saves Development Time

5/7/2003 21

® Assembly versus ‘C’

Full Control of Resource Usage

Compact and Fast Code in Small Applications

Inefficient Code in Larger Applications

Cryptic Code

Hard to Maintain

Not Portable

Limited Control of Resource Usage

Larger/Slower Code in Small Applications

Efficient Code in Larger Applications

Structured Code

Easy to Maintain

Easily Portable

5/7/2003 22

® 16-Bit Variables

Always use the Smallest Possible Data Types

16-Bit Counter:int count16 = 5; do{ }while(--count16);

LDI R24,LOW(5)LDI R25,0SBIW R24,LWRD(1)BRNE ?0004

Total 8 Bytes

8-Bit Counter:char count8 = 5; do{ }while(--count8);

LDI R16,5DEC R16BRNE ?0004

Total 6 Bytes

5/7/2003 23

® Global and Local Variables

Local VariablesInitialized at Function Start

Stored in a Register

Resides in the Register until the Function Exits

Global Variables Initialized at Startup

Stored in SRAM

Must be Loaded into Register File

5/7/2003 24

® Global versus Local Variables

Local Variable:

void main(void){char local;local = local-45;

}

SUBI R17,LOW(45)

Global Variable:char global;void main(void){global = global-45;

}

LDS R16,LWRD(global)SUBI R16,LOW(45)STS LWRD(global),R16

Total 2 Bytes Total 10 Bytes

Limit the use of Global Variables!

5/7/2003 25

® Direct Access of Global Variables

‘C’ Codeint t_count;char sec;char min;

void main(void){

sec++;min++;t_count++;

}

Assembly CodeLDS R16,LWRD(sec) ←SUBI R16,LOW(255)

STS LWRD(sec),R16 ←LDS R16,LWRD(min) ←SUBI R16,LOW(255)

STS LWRD(min),R16 ←LDS R16,LWRD(t_count) ←LDS R17,LWRD(t_count+1) ←SUBI R16,LOW(255)SBCI R17,LOW(0)

STS LWRD(t_count),R16 ←STS LWRD(t_count+1),R17 ←

← 4-byte instructions

Code Size: 40 Bytes

5/7/2003 26

® Efficient use of Global Variables

Assembly CodeLDI R30,LWRD(temp)LDI R31,LWRD(temp >> 8)LDD R16,Z+3SUBI R16,LOW(255)STD Z+3,R16LDD R16,Z+2SUBI R16,LOW(255)STD Z+2,R16LD R16,ZLDD R17,Z+1SUBI R16,LOW(255)SBCI R17,LOW(0)ST Z,R16STD Z+1,R17

Code Size: 28 Bytes

t_count

min

sec

SRAM

Z(time)Z+2Z+3

‘C’ Codetypedef struct

{int t_count; char min; char sec;

}t;t time;

Void main(void){ t *temp = &time;temp->sec++;temp->min++;temp->t_count++;

}

5/7/2003 27

® Reuse Code

Compiler Recognizes Similar Code Pieces and Collects them in FunctionsCollect Similar Code in Modules

5/7/2003 28

® Checklist to Optimize Code

Compile with Full Size OptimizationUse Local Variables whenever PossibleUse Smallest Applicable Data TypeCollect Global Variables in Structures

READ THE GENERATED ASSEMBLY CODE !!

®

~ DEVELOPMENT TOOLS ~

5/7/2003 30

® AVR Tools Overview

STK500 STK501 STK502

Starter KitsCompilersIAR SystemsCodeVisionImageCraftGCC-AVR

AVR StudioNew AVR Device

AVRISP JTAGICE

In System Programmers

Emulator Platforms

ICE200JTAGICEICE40/50

5/7/2003 31

® AVR Studio

Integrated Development Environment for AVRInlcudes Atmel Macro Assembler

Front End for Atmel Starter Kits, Programmers, and EmulatorsC and Assembly Source Level DebuggingSupports Third Party CompilersMaintains Project Information Freely Available from http://www.atmel.com

5/7/2003 32

® AVR Studio

Macro AssemblerSupports All AVR Devices

SimulatorEarly Support for New AVR Devices

Emulator InterfaceasicICE (Studio 3 Only)ICE200ICE40/50JTAGICE

Programming InterfaceAVR ISPSTK500/501/502

Integrated Development EnvironmentSource File Editor

Assembly and ‘C’ Statement Highlighting

5/7/2003 33

® STK500/STK501/STK502STK500STK500

Supports All AVR DevicesInterfaces with AVR StudioEarly Support for New DevicesPush Buttons, LEDs & RS232

STK501STK500 Expansion Module for ATmega64/128ZIF Socket & PCB FootprintOnboard 32 kHz OscillatorAdditional RS232 Port

STK501

STK502STK500 Expansion Module for ATmega169ZIF Socket & PCB FootprintOnboard 32 kHz OscillatorDemo Application with Temperature Sensor

STK502

5/7/2003 34

® FPSLIC Development KitsSTK94

AT94K40 FPSLIC & ConfiguratorTwo RS232 Serial PortsPush Buttons, LEDs, RS232 & Alpha-Numeric DisplaysSystem Designer Tool with Four Month License

STK594STK500 Expansion ModuleAT94K10 FPSLIC & ConfiguratorJTAG On-Chip Debug InterfaceOnboard 32 kHz OscillatorAdditional RS232 PortSystem Designer Tool with Four Month License

5/7/2003 35

® USB Development KitsAT43DK320A

Sample Application Code & Hardware Design DocumentationCan operate as Compound Device or Function Only

AT43DK355Sample Application Code & Hardware Design DocumentationUSB 2.0 Compliant Firmware LibraryUSB Application Wizard Compatible

AT43DK325/326Features Hot Keys, LEDs & Scan InputsUSB 2.0 Compliant Firmware LibraryCustomizable Keyboard MatrixHot Keys Software Available

5/7/2003 36

® Other ASSP Development KitsATV1-90SC

Single Emulation Platform for AT90SCEarly Support for new Devices

AT86RF401E/U-EK1Application Notes AvailableUS & European Kits AvailableSupported by AVR Studio 4Design Kit Available Including Receiver

5/7/2003 37

® AVRISP

Supports Serial In-System Programmable AVR Devices

Early Support for New AVR Devices via Firmware

Uses AVR Studio as Front End Programming Software

DOS Command Line Software Available

Supports Both 6- and 10-pin ISP ConfigurationsAdjustable Programming Speeds

Clock Adjustable from 15 Hz to 3.69 MHz

Operates on Target Voltage Supply from 2.7V to 5.5V

5/7/2003 38

® JTAG ICE Programming

In Circuit Programming using JTAGICEHigh Speed Comparable to Parallel Programming

Example:JTAG - ATmega16 Write & Verify Approximately 5 SecondsParallel - ATmega16 Write & Verify Approximately 3 Seconds

Full Support for Lock Bits and FusesOnly 4 Data Lines Required

5/7/2003 39

® ICE200

Real Emulator at Starter Kit CostControlled by AVR StudioSupports

Program BreakpointsFull Execution ControlFull I/O View & Watches

Real Time Emulation in AVR Silicon

Emulator Chip Made in the Same Process as the Real DevicePersonality Adapters Provide the Footprint for each Device

AVRSMDLow Cost Surface Mount Adapter Kit for the ICE200

ICE200

AVRSMD

5/7/2003 40

® JTAG ICE

Interfaced using AVR StudioReal-Time Emulation in Actual Silicon

Debug the Real Device at the Target LevelCommunicates Directly to the Device Through a 4-pin JTAG Interface

SupportsProgram BreakpointsData BreakpointsFull I/O View and WatchesFull Execution Control

5/7/2003 41

® ICE40/50 Emulator

ICE50Emulates all Peripherals (Both Digital and Analog)Supports all Instructions and Peripherals Real-TimeJumperless Design

All Configuration Done from AVR StudioUnlimited Number of BreakpointsSource Level DebuggingSupports the Newest Members of ATmega and ATtiny Product Families

ICE40Same Features as ICE50High End Low Cost ICE for

ATtiny26ATmega8ATmega8515ATmega8535

ICE50 Upgrade AvailableICE50

5/7/2003 42

® tinyAVR Starter Kits

AVRISP STK500

tiny11 Xtiny12 X Xtiny13 X Xtiny15 X X

tiny2313 X Xtiny26 X Xtiny28 X

5/7/2003 43

® megaAVR Starter Kits

** ATmega128 Pin Compatible with ATmega169

AVRISP STK500 STK501 STK502

mega48 X Xmega8 X X

mega88 X Xmega8515 X Xmega8535 X Xmega16 X Xmega162 X Xmega168 X Xmega169 X X ** Xmega32 X Xmega64 X X X **mega128 X X X **

5/7/2003 44

® tinyAVR Emulators

ICE200 ICE40 ICE50

tiny11 Xtiny12 Xtiny13 Xtiny15

tiny2313 Xtiny26 X Xtiny28

5/7/2003 45

® megaAVR Emulators

JTAGICE ICE40 ICE50

mega48 Xmega8 X X

mega88 Xmega8515 X Xmega8535 X Xmega16 X Xmega162 X Xmega168 Xmega169 X Xmega32 X Xmega64 X Xmega128 X X

5/7/2003 46

® Embedded Internet Toolkit

Complete Reference Design for Web ServerComplete Source Code

Modular ‘C’ SourceFull TCP/IP Stack

Complete Implementation Requires Only 32K Bytes Flash MemoryOn-Board Ethernet Interface

5/7/2003 47

® Battery Charger Kit

Reference Design based on Buck ConverterComplete Source Code Provided

Both Assembly and ‘C’tiny15 and mega8 as TargetSupports Multiple Battery Types

SLA, NiCd, NiMh, and Li-Ion Batteries

RS232 Port Available for General Use

5/7/2003 48

® AVR Butterfly

Complete Reference Design based on ATmega169

Low Power Design Methodologies

Features –SPI, USART, and USI CommunicationsProgramming Interfaces

Boot Sector, JTAG, ISP, and ParallelLight and Temperature SensorsPiezo Element for Sound GenerationJoystick Control Element

Collateral AvailableComplete Source Code and Users Guide Available from Atmel Website

5/7/2003 49

® Third Party Vendors

Compilers16+ Companies

Basic, C, C++, Forth, Pascal, etcProgrammers

35+ CompaniesField Service, ISP, JTAG, Parallel, and Production

Real Time Operating Systems8+ Companies

Adapters5+ Companies

Emulator, Programming, Prototype, and Logic Analyzer Adapters

>> See Third Party Vendors on ATMEL Website for Complete List <<

5/7/2003 50

® AVR Compilers

Third Parties Provide a Full-Scale of ‘C’ CompilersLow Cost to High End Compilers

High End CompilersIAR Embedded WorkBench AVR for AT90S and ATmega

Low Cost CompilersImageCraft ICCAVR for AT90S and Atmega (No 90S1200)ImageCraft ICCtiny for ATtiny and 90S1200CodeVisionAVR for AT90S and ATmega (No 90S1200)

FreewareGNU AVR-GCC for ATtiny, AT90S, and ATmega

5/7/2003 51

® Third Party C Compilers

++++++++++Integration with AVR

Studio

+++++++++Ease of Use

--

+++

$++

CodeVision

-√-Supports tinyAVR

√--Open Source

-++++Technical Support

Free$$$$Cost+++++++Code Size

GNU GCCImageCraftIAR

5/7/2003 52

® I Need Help!

www.atmel.comSelection Guides, Flyers, Datasheets, Application Notes, FAQ, and Errata Sheets

www.AVRfreaks.netAVR Experts Discussion ForumDesign Notes and Reference DesignsAtmel and Third Party ToolsSoftware, User Guides and LinksConsultants, Distributors and Atmel Representatives

avr@atmel.comCustomer Support Hotline

®

~ APPLICATION EXAMPLE ~

5/7/2003 54

® Application Challenge

Design a Battery Powered Thermostat Serving Different Markets with Different Feature Sets

Commercial, Industrial, Residential, etc.

Thermostat Powered by Two AA Batteries10 Year Battery Life Requirement

Total System Cost Targeted at $5Batteries Not Included

5/7/2003 55

® Current Implementation

Components8-bit Flash uController8-bit A/D ConverterPower Management CircuitryTemperature SensorLCD Display DriverCrystal Oscillator or ResonatorSeveral Passive Components

LimitationsPCB Real Estate too Large

7 Discrete Components, Greater than 3.5 x 7 cmTotal System Cost Greater than $8Battery Life Less than 5 Years

5/7/2003 56

® Design Challenges

Design for Cost ObjectivesTarget Goal to Reduce System Cost by 35%

Alternative Component SolutionsReduce Component Count with Hardware IntegrationHigh Level of Hardware/Software IntegrationRequire Low Power uController and Discrete Components

Quick Time to MarketMajority of Time Spent on DesignEase of Manufacturing, No Wasted Time on Procurement

5/7/2003 57

® ATmega169

Key Features for Thermostat ApplicationsLCD Module

100 Segment Display – 25 Segment Lines & 4 Common LinesAutomatic Programmable Contrast ControlDuty Cycle – Static, 1/2, 1/3, and 1/4Bias Voltage – Static, 1/2, and 1/3

A/D Module10-bit A/D with Differential Channels – Increased AccuracyOn-Chip Analog Reference Eliminates External Reference

Power ConsumptionOperates Down to 1.8 Volts Current Consumption in Active Mode – 300 uA @ 1 MHzCurrent Consumption in Power Down Mode < 0.5 uA

Memories16K Bytes Self Programming Flash512 Bytes EEPROM and 1K Bytes SRAM

Packaging64-pin Micro Lead Frame Package, 9 x 9 mm2

Maximum Functionality at Minimum Pin Count

5/7/2003 58

® Automatic Contrast Control

Correct Setting of LCD Contrast Requires Matching of Different Voltage and Temperature Combinations

External Temperature Sensor Communicates withuController

Correct Voltage is Generated from On-Chip LCD Driver between 2.60 to 3.35 VoltsBias Voltage can be Greater than VCC

Lower Chip CountNo Need for External Circuit

5/7/2003 59

® Benefits of Integration

Power ConsumptionSingle Chip Solution Reduces Power Consumption by 50%

Using ATmega169 Allows for Discrete Components to become uController PeripheralsPrevious Implementation Consumed Majority of Power in I/O Modules when Interfacing Discrete DevicesI/O of Peripherals are now Nodes Inside AVR

Lower System CostFewer ComponentsReduced PCB “Real Estate”

Improved ReliabilityFewer Components to Test

5/7/2003 60

® Cost ComparisonProposed Solution Existing Solution

ATmega169 $3.00 8-bit uC $2.50 LCD Panel $1.00 LCD Panel $1.00 Temp Sensor $0.40 Temp Sensor $0.40 Passives $0.20 Passives $0.50 Plastic Case $0.30 Plastic Case $0.30 PCB Board $0.10 PCB Board $0.10 A/D $1.50 LCD Interface $0.90 Brown Out $0.50 Crystal $0.30

Total Cost $5.00 Total Cost $8.00

5/7/2003 61

® ManufacturingOne Thermostat to Serve Multiple Markets

Marketing Forecasts Change

In-System Flash Program MemorySimplifies Inventory ManagementJust-In-Time DeliveryNo Scrap due to Code PatchesProgram Different Codes at End of Line

JTAG InterfaceBoundary ScanProgramming