Midterm-Lesson-2.ppt

Introduction to Embedded Systems and Ubiquitous Computing Introduction to Embedded Systems Suggested Textbooks:  Embedded System Design, by F. Vahid and Givargis, Wiley, 2002  Embedded System Design, by P. Marwedel, Kluwer Academic, 2003  Embedded System Desi...

Introduction to Embedded Systems and Ubiquitous Computing Introduction to Embedded Systems Suggested Textbooks:  Embedded System Design, by F. Vahid and Givargis, Wiley, 2002  Embedded System Design, by P. Marwedel, Kluwer Academic, 2003  Embedded System Design, by Gajski, Abdi, and et. al., Springer, 2008 Other sources  Lecture notes  handouts Winter 2010- CS 244 2 Outline What are embedded systems? Embedded System Components  Hardware/software Embedded System applications Model, languages and tools Hardware/software co-design and synthesis Reconfigurable Computing Real time Operating systems 3  What’s an Embedded System? Embedded systems =  information processing systems embedded into a larger product Two types of computing  Desktop – produced millions/year  Embedded – billions/year Non-Embedded Systems  PCs, servers, and notebooks The future of computing!  Automobiles, entertainment, communication, aviation, handheld devices, military and medical equipments. 4 Embedded Systems Devices other than desktop PCs, servers, and notebooks  Electricity running through  Perform something intelligent Hardware/software which form a component of a larger system, but are concealed from user Computers camouflaged as non-computers The future of computing! 55 An Example Embedded System Digital Camera Block Diagram 6 ES: Simplified Block Diagram actuators Winter 2010- CS 244 7  Course Outline Hardware Components Hardware si gn De ) Concept HW/SW ut, … Specification Partitioning Layo , esi s ynth ( S De sig Estimation - (C om n pil Exploration ati on , …) Software Components Software Winter 2010- CS 244 8 Validation and Evaluation (area, power, performance, …)  Components of Embedded Systems Analog Components  Sensors, Actuators, Controllers, … Digital Components Hardware  Processor, Coprocessors  Memories  Controllers, Buses  Application Specific Integrated Circuits (ASIC) Converters – A2D, D2A, … Software  Application Programs Software  Exception Handlers Winter 2010- CS 244 9 Hardware Components  Hardware Components of Embedded Systems- an example Memory Controllers Interface Software (Application Programs) Coprocessors Processor ASIC Converters Analog Winter 2010- CS 244 Digital Analog 11 Processors What is a processor?  Artifact that computes (runs algorithms)  Controller and data-path General-purpose (GP) processors:  Variety of computation tasks  Functional flexibility and low cost at high volumes (maybe)  Slow and power hungry Single-purpose (SP) processors (or ASIC)  One particular computation task  Fast and power efficient  Functional inflexibility and high cost at low volumes (maybe) Winter 2010- CS 244 12 12 GP/SP Processor Architecture Data Status Input Data-Path Controller Control Data Output Control Winter 2010- CS 244 13 13 General-purpose processors Programmable device used in a Controller Datapath variety of applications Control Register  Also known as “microprocessor” logic and file State Features register General  Program memory IR PC ALU  General datapath with large register file and general ALU Program Data User benefits memory memory  Low time-to-market and NRE costs Assembly code for:  High flexibility total = 0 Examples for i =1 to …  Pentium, Athlon, PowerPC Winter 2010- CS 244 14 Application-specific IS processors (ASIPs) Programmable processor optimized for a particular class of applications having common Controller Datapath characteristics Control Registers  Compromise between general-purpose and logic and ASIC (custom hardware) State register Features Custom ALU  Program memory IR PC  Optimized datapath Data  Special functional units Program memory Benefits memory  Some flexibility, good performance, size and Assembly code power for: Examples total = 0 for i =1 to …  DSPs, Video Signal Processors, Network Processors,.. Winter 2010- CS 244 15 Application-Specific ICs (ASICs) Digital circuit designed to execute Controller Datapath exactly one program Control logic index  coprocessor, hardware accelerator total State Features register +  Contains only the components needed Data to execute a single program memory  No program memory Benefits  Fast  Low power  Small size Winter 2010- CS 244 16  Application Specific Circuits (ASIC) Custom-designed circuits necessary if ultimate speed or energy efficiency is the goal and large numbers can be sold. Approach suffers from long design times and high costs. Winter 2010- CS 244 17 GP vs. SP Processors GP: ASIC: Programmable controller Hardwired controller  Control logic is stored in  No need for program memory memory and cache  Fetch/decode overhead  No fetch/decode overhead Highly general data-path Highly tuned data-path  Typical bit-width (8, 16, 32,  Custom bit-width 64)  Custom arithmetic/logic units  Complete set of  Custom set of registers arithmetic/logic units  Large set of registers Low NRE/sale-volume High NRE/sale-volume Winter 2010- CS 244 18 18 Storage What is a memory?  Artifact that stores bits  Storage fabric and access logic Write-ability  Manner and speed a memory can be written Storage-permanence  ability of memory to hold stored bits after they are written Many different types of memories  Flash, SRAM, DRAM, etc. Common to compose memories Winter 2010- CS 244 19 19 Write-ability Ranges of write ability  High end Processor writes to memory simply and quickly E.g., RAM  Middle range Processor writes to memory, but slower E.g., FLASH, EEPROM  Lower range Special equipment, “programmer”, must be used to write to memory E.g., EPROM, OTP ROM  Low end Bits stored only during fabrication E.g., Mask-programmed ROM Winter 2010- CS 244 20 20 Storage-permanence Range of storage permanence  High end Essentially never loses bits E.g., mask-programmed ROM  Middle range Holds bits days/months/years after memory’s power source turned off E.g., NVRAM  Lower range Holds bits as long as power supplied to memory E.g., SRAM  Low end Begins to lose bits almost immediately after written E.g., DRAM Winter 2010- CS 244 21 21  Memory Types Mask-programmed ROM In-system programmable Ideal Storage-permanence OTP ROM EPROM EEPROM Flash NVRAM Nonvolatile SRAM/DRAM Write-ability Winter 2010- CS 244 22 22 Communication What is a bus?  An artifact that transfers bits  Wires, air, or fiber and interface logic Associated with a bus, we have:  Connectivity scheme Serial Communication Parallel Communication Wireless Communication  Protocol Ports Timing Diagrams Read and write cycles  Arbitration scheme, error detection/correction, DMA, etc. Winter 2010- CS 244 23 23 Serial Communication A single wire used for data transfer One or more additional wires used for control (but, some protocols may not use additional control wires) Higher throughput for long distance communication  Often across processing node Lower cost in terms of wires (cable) E.g., USB, Ethernet, RS232, I2C, etc. Winter 2010- CS 244 24 24 Parallel Communication Multiple buses used for data transfer One or more additional wires used for control Higher throughput for short distance communication  Data misalignment problem  Often used within a processing node Higher cost in terms of wires (cable) E.g., ISA, AMBA, PCI, etc. Winter 2010- CS 244 25 25 Wireless Communication Infrared (IR)  Electronic wave frequencies just below visible light spectrum  Diode emits infrared light to generate signal  Infrared transistor detects signal, conducts when exposed to infrared light  Cheap to build  Need line of sight, limited range Radio frequency (RF)  Electromagnetic wave frequencies in radio spectrum  Analog circuitry and antenna needed on both sides of transmission  Line of sight not needed, transmitter power determines range Winter 2010- CS 244 26 26 Peripherals Perform specific computation task Custom single-purpose processors Designed by us for a unique task Standard single-purpose processors “Off-the-shelf” pre-designed for a common task Winter 2010- CS 244 27 27 Timers Timers: measure time intervals  To generate timed Basic timer output events Clk 16-bit up counter 16 Cnt  To measure input events Top  Top: max count Reset reached Range and resolution Winter 2010- CS 244 28 28 Counters Counter: like a timer, but counts pulses on a general Timer/counter input signal rather Clk 2x1 mux 16-bit up counter 16 Cnt than clock Cnt_in Top  e.g., count cars passing Reset over a sensor Mode  Can often configure device as either a timer or counter Winter 2010- CS 244 29 29 Watchdog Timer Must reset timer every X time unit, else timer generates a signal Common use: detect failure, self-reset Winter 2010- CS 244 30 30 UART UART: Universal Asynchronous Receiver Transmitter  Takes parallel data and transmits serially  Receives serial data and converts to parallel Parity: extra bit for simple error checking Start bit, stop bit Baud rate  Signal changes per second  Bit rate, sometimes different Winter 2010- CS 244 31 31 Pulse Width Modulator (PWM) Generates pulses with specific high/low times Duty cycle: % time high  Square wave: 50% duty cycle Common use: control average voltage to electric device  Simpler than DC-DC converter or digital- analog converter  DC motor speed, dimmer lights Winter 2010- CS 244 32 32 LCD Liquid Crystal Display N rows by M columns Controller build into the LCD module Simple microprocessor interface using ports Software controlled Winter 2010- CS 244 33 33 Keypad N1 N2 N3 k_pressed N4 M1 M2 M3 M4 4 key_code key_code keypad controller N=4, M=4 Winter 2010- CS 244 34 34 Stepper Motor Controller Stepper motor: rotates fixed number of degrees when given a “step” signal  In contrast, DC motor just rotates when power applied, coasts to stop Rotation achieved by applying specific voltage sequence to coils Controller greatly simplifies this Winter 2010- CS 244 35 35 Analog-to-Digital Converter Vmax = 7.5V 1111 4 4 7.0V 1110 6.5V 1101 3 3 analog output (V) analog input (V) 6.0V 1100 5.5V 1011 2 2 5.0V 1010 4.5V 1001 4.0V 1 1 1000 3.5V 0111 3.0V 0110 time time t1 t2 t3 t4 t1 t2 t3 t4 2.5V 0101 2.0V 0100 0100 1000 0110 0101 0100 1000 0110 0101 1.5V 0011 Digital output Digital input 1.0V 0010 0.5V 0001 0V 0000 proportionality Analog to Digital Digital to Analog (A/D) (D/A) Winter 2010- CS 244 3636 Summary Hardware: Information Processing  Processors  Memories  Communication  Peripherals Winter 2010- CS 244 37