CSE 466 Software for Embedded Systems. What is an embedded system?

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1 CSE 466 Software for Embedded Systems The wrap up Recall the introduction what are embedded systems? What we covered in the course CSE 466 Wrap Up 1 What is an embedded system? Let s proceed inductively with a bunch of examples from research and practice CSE 466 Wrap Up 2 1

2 Car From CSE 466 Wrap Up 3 Phone? Source: Pro: lots of sensors mobile Con: multi-purpose, runs apps CSE 466 Introduction 4 2

3 LS3 / Bigdog CSE 466 Wrap Up 5 ATM CSE 466 Wrap Up 6 3

4 Hearing aid CSE 466 Wrap Up 7 Doorknob CSE 466 Wrap Up 8 4

5 WISP: Wireless Identification and Sensing Platform RFID reader Ethernet PC RF Power Data Digital logic of RFID tag shifted to SW another SW defined radio. For low power operation, micro sleeps most of the time. More power more updates / s WISP CSE 466 Wrap Up 9 So what is an embedded computing system? A system with no OS? This definition probably makes less sense as microelectronics get more capable A system that is tightly coupled to the physical world The brains of a smart object A device that doesn t plug into the wall (battery or energy harvesting) A device that communicates wirelessly? Elecia White (author of Making Embedded Systems): a computerized system that is purpose-built for its application A system that you need a cross-compiler to program CSE 466 Wrap Up 10 5

6 A key trend reshaping embedded systems Energy Efficiency Scaling 1.0E E+06 Energy Efficiency (Instr / uj) Brain 1.0E E+02 Cray 1 Dell Lattitude E E E E-04 DEC PDP-11/20 486/25 IBM PC-AT Dell Dimension E-06 Univac III 1.0E-08 Eniac 1.0E Wrap Up What is this class about? Embedded Computer Signal conditioning electronics CSE466 SW for embedded systems Sensors / transducers Actuators EE205 Signal conditioning Physical world We will talk about both how to program embedded systems microcontrollers, interrupts, ADC interfacing communication (wired protocols) real-time constraints power constraints what to program some signal processing, communication, control techniques CSE 466 Wrap Up 12 6

7 What did we cover? The Hardware Microcontrollers Interrupts Analog to Digital Conversion Interfacing Communication Modulation Wired Communication Wireless Communication Error Control Codes A real wireless communication system: Simplici-TI Actuation: Control and Estimation Control (PID) State estimation / Kalman filters Operating System Issues Tasks and Scheduling Task Control Blocks Finite State Machines Critical Systems Real Embedded OSes CSE 466 Wrap Up 13 Hardware & Signal Processing Microcontrollers Interrupts Analog to Digital Conversion Interfacing RC Circuits Op amps Signal processing / filtering (Analog and digital derived low pass IIR from RC) Synchronous detection (E-Field lab) Goertzel CSE 466 Wrap Up 14 7

8 Communication General Bandwidth, SNR, Capacity Modulation and Demodulation (relevant for both sensing & comms) Looked at synchronous detection, with multiple orthogonal carriers TDMA, FDMA, CDMA Multiply accumulate operation does inner product orthogonality, linearity Wired Communication SPI, I2C, USB, CANBUS, Ethernet, EtherCAT Wireless Communication Radio Components: Antenna, Oscillator, Modulator, Demodulator, Low pass Filter Analog and digital implementation Antenna related issues: transmission lines, impedance matching Error Control Codes CRC, Hamming Code, LDPC & sparse graph, rateless codes (iterative decoding) A real wireless communication system: Simplici-TI CSE 466 Wrap Up 15 Actuation: Control and Estimation Control (PID) Bang-Bang, proportional control, PID control State estimation / Kalman filters CSE 466 Wrap Up 16 8

9 Operating System Issues Tasks and Scheduling Hard vs soft realtime Scheduluers: infinite loop, synchronized infinite loop, preemptive round robin, preemptive priority based Rate-monotonic scheduling for real-time Oses Static priorities set based on job size (smaller more often) Provides response time guarantees Trade off between utilization and response time Task Control Blocks Inter-task communication Cooperation, synchronization, sharing, critical sections, Semaphores Finite State Machines Critical Systems Dependability, availability & reliability, safety, security Fail-safe [safe state medical], Fail-operational [elevator], Fail passive [autopilot does no harm] Balance development cost vs failure cost Real Embedded Oses Quick survey of real-time: RTLinux, RTAI, uc/os-ii, Free RTOS Sensor network: Contiki, Tiny OS Computational RFID: Dewdrop, Mementos CSE 466 Introduction 17 The End Thank you! CSE 466 Wrap Up 18 9