Philips Lifeline Ø http://www.lifelinesys.com/content/lifeline-products/auto-alert Chenyang Lu 1
Smartphone for Medicine Ø http://video.msnbc.msn.com/rock-center/50582822 2
Proposal Presenta5on Ø 2/12, in class q Email Rahav your slides by 11:30am. Ø 15 min/team (hard limit) q Leave 3 min for discussion. 3
Proposal Ø One proposal per team, one page q Team members q Concise description of project q Responsibilities of each member q Specific equipment needed Ø Written proposal due: 2/12, 11:59pm q Email to Rahav q Subject: [CSE 467S] Proposal: Project Name 4
Embedded Systems Design Ø What s unique about embedded systems? Ø Why use a microprocessor? Ø Challenges in developing embedded systems Ø Design methodology Chenyang Lu 5
System Characteris5cs Ø Non- func>onal requirements q Real- >me q Low power q Reliability q Form factor q Cost q Ø Short development cycles Ø Small teams Chenyang Lu 6
Real- Time Ø System works properly only if it meets timing constraints. q Rate: complete N tasks per sec q Deadline: complete a task within D sec Ø Timing constraints q Hard: violating timing constraint à failure Anti-lock Brake System CD burner Air traffic control q Soft: violating timing constraint à poor service Video GPS map Audio? Chenyang Lu 7
Power Ø Battery-powered devices: battery life q Smart phone, smart watch, wireless sensor... Ø Wall-powered devices q Cooling. q Energy bills. Chenyang Lu 8
Great Duck Island Require 9 month life0me on ba3eries Chenyang Lu 9
Cost " Constrain memory size, processor speed, I/O interfaces Ø Example: Intel imote 2 Multicolor status LED Source: Lama Nachman, presentation at TinyOS Technology Exchange ARM* core SRAM FLASH BT radio 2.4 GHz antenna Optional external antenna connector Optional voltage regulator (bottom) Stackable connectors (top and bottom) Chenyang Lu 10
imote 2 Price Sheet Item Description Cost PXA 270/271/273 Discrete / 32M F+S / 32M F $17.75 / $32.44 / $23 PMIC Dialog power management IC $3.75 CC2420 ChipCon 802.15.4 Radio $3.6 Crystals 13 MHz, 16 MHz, 32KHz ~$2.8 Antenna Giga Ant surface mount $1.5 LED + Driver Agilent $1 Connectors Basic (2) + Advanced (2) $1 + $1.6 Passives ~ $9 Fab + Assembly Rough estimate from imote 1 ~ $10 Total With PXA 270 / 271 / 273 $52 + F / $67 / $57 Prices above assume 1K units, except for PXA and PMIC (special Intel pricing) PXA 270 configuration will need an external flash + bringing out addr/data bus Chenyang Lu 11
imote 2 : Cost Considera5on Ø No A/D on mote board q Digital sensors don t need it q Applications have different A/D requirements (number of channels, sampling rate, filtering ) q A/D will be integrated into the sensor board Ø SDIO (Secure Digital I/O) q Connector is too big (30x30 mm) and costly ($1.74) to be included on imote 2 board q Pins will be exposed through basic connector Chenyang Lu 12
Design Teams Ø Often designed by a small team Ø Meet tight deadlines q 6 month market window is common. q Ex. Can t miss holiday shopping season for gadgets. Ø Compare to teams for q Intel microprocessors q Windows Chenyang Lu 13
Embedded Systems Design Ø What s unique about embedded systems? Ø Why use a microprocessor? Ø Challenges in developing embedded systems Ø Design methodology Chenyang Lu 14
Embedding a Computer CPU output input analog analog actuators analog analog sensors embedded computer mem Chenyang Lu 15
Alterna5ve Technology Ø Application-Specific Integrated Circuit (ASIC) Ø Microprocessor Ø Field-Programmable Gate Array (FPGA) Ø Why do we use a microprocessor? Chenyang Lu 16
ASIC Ø Ex: Digital baseband processing for cell phones ü Performance: Fast! ü Power: Fewer logic elements à low power û Development cost: Very high q 2 million $ for starting production of a new ASIC q Needs a long time and a large team û Reprogrammability: None Single-purpose devices Difficult to patch and upgrade Chenyang Lu 17
Microprocessor Performance Paradox Ø Programmable computers are fundamentally slow! q fetch, decode instructions Ø But engineering optimization mitigates limitations q cache q heavily pipelined q clock frequency q circuit density q aggressive VLSI technology q multi-core q large design teams made it happen Chenyang Lu 18
Microprocessor: Power Ø Improve performance at the cost of power! q Performance/watt remains low. Ø Solution q Microprocessors offer features for power management. q Software manages power consumption. Chenyang Lu 19
Microprocessor: Re- programmability Let software do the work! Ø Fast and low-cost development Ø Easy to upgrade, patch, and reuse Ø Simplify the design of a family of products Ø Same hardware can run multiple applications q Example: iphone q May have fewer transistors than ASICs Chenyang Lu 20
Microprocessor vs. ASIC Ø Since Wednesday, its 19th day on Mars, the Spirit had sent back to Earth only meaningless radio noise or simple beeps acknowledging receipt of commands If the solware is awry, NASA can fix it from Earth by beaming patches across more than 100 million miles of space or by reboo>ng the rover's computer. But if the problem lies with the rover's hardware, the situa>on would be far more grave. NASA Gets Half- Hour of Signals From Rover By ANDREW BRIDGES, AP Chenyang Lu 21
FPGA Ø Programmable hardware Ø Combine the benefits of ASIC and microprocessor q Hardware implementation à high performance/watt q Reprogammable à lower development cost Chenyang Lu 22
Structure of an FPGA Chip Chenyang Lu 23
FPGA: Limita5ons Ø Many overhead transistors à waste power! q Configurable connections q Personalization memory: 70% of the transistors Ø More difficult to program than software Ø More commonly used for prototyping Chenyang Lu 24
State of the Prac5ce Ø Microprocessor is the dominant player q Flexibility and low development cost >> low performance/watt q Power management is crucial Ø Microprocessor + ASIC is common q Example: cell phone Ø FPGA is expected to play an increasing role Chenyang Lu 25
Embedded Systems Design Ø What s unique about embedded systems? Ø Why use a microprocessor? Ø Challenges in developing embedded systems Ø Design methodology Chenyang Lu 26
Challenge: Non- func5onal Constraints Ø How do we meet deadlines? q Faster hardware or better software? Ø How do we minimize power? q Turn off unnecessary logic? q Reduce memory accesses? q Slow down CPU? Ø Reduce cost Ø Tradeoffs among constraints Ø Optimization & analysis are important! Chenyang Lu 27
Challenge: Debugging and Tes5ng Ø Deal with noise and uncertainty in the physical world q Sensors and actuators Ø Hard to debug q No display; no keyboard; wireless Ø How to test real-time characteristics? Chenyang Lu 28
Embedded Systems Design Ø What s unique about embedded systems? Ø Why use a microprocessor? Ø Challenges in developing embedded systems Ø Design methodology Chenyang Lu 29
Design Methodologies requirements specifica>on architecture component design system integra>on Chenyang Lu 30
Requirements Ø Plain language description of what the user wants and expects to get. Ø May be developed in several ways: q talking directly to customers; q talking to marketing representatives; q providing prototypes to users for comment. Chenyang Lu 31
Func5onal & Non- func5onal Requirements Ø Functional requirements: q output as a function of input Ø Non-functional requirements: q timing constraints q power consumption q size q weight q reliability Chenyang Lu 32
Example: GPS moving map requirements Ø Obtains position from GPS Ø Paints map from local database. I-78 Scotch Road lat: 40 13 lon: 32 19 Chenyang Lu 33
GPS moving map needs Ø Functionality q For automotive use. q Show major roads and landmarks. Ø User interface q At least 400 x 600 pixel screen. q Three buttons max. q Pop-up menu. Ø Performance q No more than 1 sec power-up. q Lock onto GPS within 15 seconds. q Update location every 0.25 sec. Chenyang Lu 34
GPS moving map needs, cont d. Ø Cost: $500 street price = $100 cost of goods. Ø Physical size/weight: fit in hand. Ø Power consumption: run for 8 hours on four AA batteries. Chenyang Lu 35
GPS Map Requirements Form name GPS moving map purpose consumer-grade moving map for driving inputs power button, two control buttons outputs back-lit LCD 400 X 600 functions performance manufacturing cost power 5-receiver GPS; three resolutions; displays current lat/lon updates screen within 0.25 sec of movement $100 cost-of-goodssold 100 mw physical size/weight no more than 2: X 6:, 12 oz. Chenyang Lu 36
Specifica5on Ø Precise description of the system q should not imply a particular architecture; q provides input to the architecture design process. Ø Include functional and non-functional elements Ø UML: Unified Modeling Language q Not required in this course Chenyang Lu 37
GPS Specifica5on Ø What is received from GPS; Ø Map data; Ø User interface; Ø Operations required to satisfy user requests; Ø Background operations needed to keep the system running. Chenyang Lu 38
Architecture Design Ø What major components go satisfying the specification? Ø Hardware components: q CPUs, peripherals, etc. Ø Software components: q Major programs and their operations. Ø Take into account functional and non-functional specifications. Chenyang Lu 39
GPS Moving Map: Block Diagram GPS receiver search engine renderer display database user interface Chenyang Lu 40
GPS Moving Map: Hardware Architecture display frame buffer memory CPU GPS receiver panel I/O Chenyang Lu 41
GPS Moving Map: SoSware Architecture posi>on database search renderer pixels user interface >mer Chenyang Lu 42
Designing components Ø Must spend time architecting the system before coding. Ø Components may be q ready-made q modified from existing designs q designed from scratch Chenyang Lu 43
System Integra5on Ø Put together the components. Ø Many bugs appear only at this stage. Ø Individual components should be tested first! Chenyang Lu 44
Summary Ø Why do we use microprocessors today? Ø Embedded systems pose many challenges: design time, deadlines, power, cost Ø Design methodologies help manage the design process. Chenyang Lu 45
Reading Ø Textbook: Sec 1.1, 1.2, 1.3 Ø N. Tredennick and B. Shimamoto, Go Reconfigure, IEEE Spectrum, 40(12): 36-40, 2003. (Optional but interesting) Chenyang Lu 46