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1、CS4101 嵌入式系統概論 Design and Development,http:/ and more physical things will be augmented or embedded with computing Things become “smarter” Computing becomes ubiquitous An embedded system is a system that is embedded with programmable computers for specific applications of that system Why embedded sy
2、stems? Faster, more flexible development at lower cost More complex functionalities,http:/ You Have a Product Idea,To develop a device that can record, for each day, the number of stairs that the user has climbed up or down From this number, we can then calculate the amount of CO2 saved and calories
3、 burned Let us call this device stair counter How to start from here?,http:/ Design Flow,requirements,specification,architecture,component development,system integration,Top-down design,Bottom-up design,Real design often iterative,http:/ language description of what the user wants and expects to get
4、 e.g. to develop a device that can record, for each day, the number of stairs that the user has climbed up or down Describe how the end product is used by the user May be developed in several ways: talking directly to customers talking to marketing representatives providing prototypes to users for c
5、omment,http:/ need to know target customers and business model Stair counter as an add-on of cell phone Stair counter as a consumer product Stair counter as a gift ,http:/ requirements: Internals as a black box and describe only the outputs as a function of input; Show number of stairs climbed up or
6、 down Show amount of CO2 saved Do not count in other cases Non-functional requirements: Performance, reliability, etc. Size, weight, etc. Power consumption Cost ,Describe “WHAT”, not “HOW”,http:/ Form,http:/ precise, usually quantitative description of the system: Should not imply a particular archi
7、tecture List assumptions e.g., update screen 0.25 sec after each step, error rate 95%, cost $300 May include functional and non-functional elements May be executable or may be in mathematical form for proofs e.g. UML (Unified Modeling Language),http:/ Design,What major components satisfy the specifi
8、cation? HOW Need to know what are available Hardware components: CPUs, peripherals, etc. e.g. MSP430 CPU, 3-axis accelerometer Software components: Major programs and their operations e.g. no OS, accelerometer driver, LCD driver Must take into account functional and non-functional specifications,htt
9、p:/ Considerations,Environment which the embedded system is in External and internal stimulus sources that interact with the embedded system I/O Actions and events caused by stimulus Elements of the embedded system that could be affected by the stimulus Desired system responses to the stimulus, whic
10、h reflects one or more system requirements algorithm/workflow How the system responses can be measures,http:/ Development,Actual implementation of individual hardware and software components Must spend time architecting the system before you start coding Some components are ready-made, some can be m
11、odified from existing designs, others are to be designed from scratch e.g. MSP430 CPU, 3-axis accelerometer Good surveys help,http:/ Integration,Put together the components Many bugs appear only at this stage Require good interface definition from the start Have a plan for integrating components to
12、uncover bugs quickly, test as much functionality as early as possible test and verification,http:/ Development,Now that you have better idea of the requirements, specifications, and architecture of the stair counter How to proceed to develop the components and integrate the system? But, Real hardwar
13、e? Programming environment?,http:/ Environment,Host: a computer running programming tools for development Target: the HW on which code will run After program is written, compiled, assembled and linked, it is transferred to the target,Host system,Target system,X86,MSP430,http:/ If Real HW Not Availab
14、le?,Development board: Before real hardware is built, software can be developed and tested using development boards Development boards usually have the same CPU as the end product and provide many IO peripherals for the developed software to use as if it were running on the real end product Tools fo
15、r program development Integrated Development Environment (IDE): cross compiler, linker, loader, OS and related libraries and packages,http:/ Compiler,Runs on host but generates code for target Target usually have different architecture from host. Hence compiler on host has to produce binary instruct
16、ions that will be understood by target,http:/ Process,Process for creating instructions that are built on host but meant for the target Tools are compatible with each other a toolchain Binutils: as, ld Glibc：C runtime Lib GCC：C/C+ compiler,http:/ computers: Linker: creates an image file to be run on
17、 host Loader: loads image file into memory during run-time For embedded systems: Locater: creates a file, containing binary image or other format, that will be copied onto target, which run on its own (not through loader) It needs exact addresses beforehand Certain parts of program need in ROM and s
18、ome in RAM Normally done by dividing program in segments Locator needs to be told where in memory to place segments,http:/ of a system usually involves: Requirement, specification, architecture design, component development, system integration, test and validation Development environment of an embedded system often includes Development host with toolchain: cross compiler, linker/loader, library, emulator Development board,http:/