EL-GY 6483: REAL TIME EMBEDDED SYTEMS
NYU TANDON SCHOOL OF ENGINEERING
Spring 2025
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EL-GY 6483: REAL TIME EMBEDDED SYTEMS
• Instructor:
• Professor Matthew Campisi
• Office: 370 Jay Street, 8th Floor
• Email: mcampisi@nyu.edu
• Teaching Assistants:
• TBD
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Logistics
• Class Meeting Times and Locations:
• 370 Jay Street Rm. 202/ZOOM
• Textbook – No required Text, but many reference
materials..
• Quizzes:
• 2 Open Book
• Embedded Challenge Spring 2025
• TBD (More info discussed in class)
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• Grading Policy
• Exams 40% (20% each)
• Homework (Given weekly) 20%
• Embedded Challenge 40%
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EMBEDDED SYSTEMS
 EMBEDDED SYSTEMS
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
EMBEDDED SYSTEMS
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What are Embedded Systems?
• Anything that uses a microprocessor but isn’t a general-purpose computer
 Smartphones?
 Set-top boxes
 Televisions
 Video Games
 Refrigerators
 Cars
 Planes
 Elevators
 Remote Controls
 Alarm Systems
• The user “sees” a smart (special-purpose) system as opposed to the computer inside
the systems
• “how does it do that?”
• “it has a computer inside of it”
• “oh, BTW, it does not or cannot run Windows or MacOS”
• The end-user typically does not or cannot modify or upgrade the internals
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What about this course?
• Hardware
• I/O, peripherals: sensors/actuators, memory, busses, devices, control
logic, interfacing hardware to software
• Software
• Lots of C and assembly, device drivers, low-level real-time issues,
scheduling
• Concurrency; interrupts
• Software/Hardware interactions
• Where is the best place to put functionality – hardware or software?
• What are the costs:
• Performance
• Memory requirements (RAM and/or FLASH ROM)
• Integration of hardware and software
• Programming, logic design, architecture
• Algorithms, mathematics and common sense
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Careers in Embedded?
• Automotive systems
• Perhaps designing and developing “drive-by-wire” systems
• Self-driving vehicles
• Telecommunications
• Medical Devices
• Consumer electronics
• Cellular phones, MP3 devices, integrated cellular/tablet
• Set-top box and HDTV
• Home and Internet appliances/ IOT
• Your refrigerator will be on the internet more than you are!
• Defense and weapons systems
• Process control
• Gasoline processing, chemical refinement
• Automated manufacturing
• Supervisory Control and Data Acquisition (SCADA)
• Space communications
• Satellite communications
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Goals of the Course
• High-level Goals
• Understand the scientific principles and concepts behind embedded systems
• Obtain hands-on experience in programming embedded systems
By the end of the course, you should be able to
• Understand the “big ideas” in embedded systems
• Obtain direct hands-on experience on both hardware and software elements
commonly used in embedded systems design
• Understand the basics of embedded system application concepts such as signal
processing and feedback control
• Understand and be able to discuss and communicate intelligently about:
• Embedded processor architecture and programming
• OS primitives for concurrency, timeouts, scheduling, communication and
synchronization
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The Big Ideas
• HW/SW Boundary
• Non processor centric view of architecture
• Bowels of the operating software
• Specifically, basic real-time operation with interrupts
• Concurrency
• Real-world design
• Performance vs. cost tradeoffs
• Analyzability
• How do you “know” that your drive-by-wire system will function correctly?
• Application-level techniques
• Signal processing, control theory
• Semaphores, locks, atomic sections
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What is an Embedded system?
• An embedded system is a computer system with a dedicated function within a larger
mechanical or electrical system, often with real-time computing constraints. It
is embedded as part of a complete device often including hardware and mechanical
parts. Embedded systems control many devices in common use today.
• Typically dedicated software (may be user customizable)
• Often replaces previously electromechanical components
• Often no “real” keyboard
• Often limited display or no general purpose display device
However, every system is unique – there are always exceptions
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CPU: An All-Too-Common View of Computing
• Measured by:
• Performance
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An Advanced Computer Engineer’s View
• Measured by: Performance
• Compilers matter too…
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An Enlightened Computer Engineer’s View
• Measured by: Performance, Cost
• Compilers & OS matters
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An Embedded Computer Designer’s View
• Measured by: Cost, I/O connections, Memory Size,
Performance
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An Embedded Control System Designer’s View
• Measured by: Cost, Time to Market, Cost, Functionality, Cost
& Cost
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Atmel | SMART SAM D21 Processor (ARM Cortex M0+)
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Atmel | SMART SAM D21 Processor (ARM Cortex M0+)
• Data sheet (All 1100 Pages!)
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A Customer’s View
• Reduced Cost
• Increased Functionality
• Improved Performance
• Increased Overall Dependability
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Why are Embedded Systems Different?
Four General Categories of Embedded Systems
1. General Computing
• Applications similar to desktop computing, but in an embedded
package
• Video games, set-top boxes, wearable computers, automatic tellers
• Tablets, Phablets
2. Control Systems
• Closed loop feedback control of real-time system
• Vehicle engines, chemical processes, nuclear power, flight control
3. Signal Processing
• Computations involving large data streams
• Radar, Sonar, Video compression
4. Communication & Networking
• Switching and information transmission
• Telephone system, Internet
• Wireless everything
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Typical Embedded System Constraints
• Small Size, Low Weight
• Handheld electronics
• Transportation applications weight costs money
• Low Power
• Battery power for 8+ hours (laptops often last only 2 hours)
• Limited cooling may limit power even if AC power available
• Harsh environment
• Heat, vibration, shock
• Power fluctuations, RF interference, lightning
• Water, corrosion, physical abuse
• Safety critical operation
• Must function correctly
• Must not function incorrectly
• Extreme cost sensitivity
• $0.05 adds up over 1,000,000 units
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Embedded System Design World-View
A complex set of tradeoffs:
• Optimize for more than just speed
• Consider more than just the computer
• Take into account more than just initial product design
Multi-Discipline
• Electronic Hardware
• Software
• Mechanical Hardware
• Control Algorithms
• Humans
• Society/Institutions
Multi-Phase
• Requirements
• Design
• Manufacturing
• Deployment
• Logistics
• Retirement
Multi-Objective
• Dependability
• Affordability
• Safety
• Security
• Scalability
• Timeliness
X X
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Embedded System Designer Skill Set
• Appreciation for multidisciplinary nature of design
• Both hardware & software skills
• Understanding of engineering beyond digital logic
• Ability to take project from specification through production
• Communication and Teamwork skills
• Work with other disciplines, manufacturing, marketing
• Work with customers to understand the real problem being solved
• Make a good presentation; even better – write “trade rag” articles
• And, by the way, technical skills too…..
• Low-level: Microcontrollers, FPGA/ASIC, assembly language, A/D, D/A
• High-Level: Object oriented design, C/C++, Real Time Operating Systems
• Meta-level: Creative solutions to highly constrained problems
• Likely in the future: Unified Modeling Language, embedded networks
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Microprocessor or Microcontroller?
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A Little History
What is a computer?
 One that computes; specifically: programmable electronic device that can
store, retrieve and process data (from Merriam-Webster Dictionary)
 A computer is a machine that manipulates data according to a list of
instructions (from Wikipedia)
Classifications of Computers:
 Personal computers
 Mainframes
 Supercomputers
 Dedicated controllers – Embedded controllers
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MAINFRAMES
 Massive amounts of memory
 Use large data words – 64 bits or greater
 Mostly used for military defense and large business data
processing
 Examples: IBM 4381; Honeywell DPS8
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Personal Computers
 Any general-purpose computer
 Intended to be operated directly by
an end user
 Range from small microcomputers that
work with 4-bit words to PCs working
with 32-bit words or more
 They contain a Processor – called
different names
 Microprocessor – built using Very-
Large-Scale Integration technology;
the entire circuit is on a single chip
 Central Processing Unit (CPU)
 Microprocessor Unit (MPU) –
similar to CPU
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Supercomputers
 Fastest and most powerful mainframes
 Contain multiple central processors (CPU)
 Used for scientific applications and number
crunching
 Now have petaflops performance –
FLoating-point Operations Per Second
(FLOPS)
 Used to measure the speed of the
computer
 Examples of special-purpose supercomputers:
 Belle, Deep Blue, and Hydra, for playing chess
 GRAPE, for astrophysics and molecular
dynamics
 Deep Crack, for breaking the DES cipher
 MDGRAPE3, for protein structure computation
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Microcontrollers – Embedded Systems
 An embedded system is a special-purpose computer system
designed to perform one or a few dedicated functions often
with real-time
 An integrated device which consists of multiple devices
 Microprocessor(MPU)
 Memory
 I/O (Input/Output) ports
 Often has its own dedicated software
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A little about
Microprocessor-based Systems ….
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Evolution
 First came transistors
 Integrated circuits
 SSI (Small-Scale Integration) to ULSI
 Very Large Scale Integration circuits (VLSI)
 1 – Microprocessors (MPU)
 Microcomputers (with CPU being a microprocessor)
 Components: Memory, CPU, Peripherals (I/O)
 2 – Microcontroller (MCU)
 Microcomputers (with CPU being a microprocessor)
 Many special function peripheral are integrated on a single
circuit
 Types: General Purpose or Embedded System (with special
functionalities)
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Microprocessor-Based Systems
 Central Processing Unit
(CPU)
 Memory
 Input/Output (I/O) circuitry
 Buses
 Address bus
 Data bus
 Control bus
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Microprocessor-Based System with Buses:
Address, Data and Control
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Microprocessor-Based Systems
Microprocessor
 The microprocessor (MPU) is a computing and logic device that
executes binary instructions in a sequence stored in memory
 Characteristics:
 General purpose central processing unit (CPU)
 Binary
 Register-based
 Clock-driven
 Programmable
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
The Evolution of CPUs
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Transistors
 Vacuum Tube: A device to control,
modify, and amplify electronic
signals
 Then came Transistors
 Designed by John Bardeen,
Will Shockley, and walter
Brattain – scientists at the Bell
Telephone Laboratories in
Murray Hill, New Jersey, 1947
 In 1960, Jack Kilby and Robert
Noyce designed the first
integrated circuit (IC)
 Fairchild company manufactured
logic gates
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Integrated Circuits
 Advances in
manufacturing allowed
packing more transistors
on a single chip
 Transistors and
Integrated Circuits from
SSI(Small-Scale
Integration) to ULSI
 Birth of a
microprocessor and its
revolutionary impact
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Microprocessors
 Noyce and Gordon Moore
started Intel
 Intel designed the first
calculator
 Intel designed the first
programmable calculator
 Intel designed the first
microprocessor in 1971
 Model 4004
 4-bit; 2300 transistors,
640 bytes of memory,
108 KHz clock speed
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First Processors
 Intel released the 8086, a 16-bit microprocessor, in 1978
 Motorola followed with the MC68000 as their 16-bit processor
 The 16-bit processor works with 16 bit words rather than 8
bit words
 Instructions executed faster
 Provide single instructions for more complex instructions
such as multiply and divide
 16-bit processors evolved into 32-bit processors
 Intel released the 80386
 Motorola released the MC 68020
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Evolution of CPUs
In 1965, Gordon Moore, co-founder of Intel, indicated that the number of transistors per square inch
on integrated circuits had doubled every year since the integrated circuit was invented. Moore
predicted that this trend would continue for the foreseeable future.
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Evolution of CPUs
 Intel®Core i7
 Intel®Core i7-5960X Processor Extreme
Edition
 20M Cache, up to 3.50 GHz
 8 Cores, 16 Threads
 64-bit Instruction Set
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Microprocessor-based Systems
Memory Types
 R/W: Read/Write Memory; also called RAM
 It is volatile (losses information as a power is removed)
 Write means the processor can store information
 Read means the processor can retrieve information from the memory
 Acts like a Blackboard!
 ROM: Read-Only Memory
 It is typically non-volatile (permanent) – can be erasable
 It is similar to a page from your textbook
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Microprocessor-Based Systems
Memory Classification
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Microprocessor-Based Systems
 Memory Classification
Electronically Erasable
PROM
Onetime programmable
• One transistor and capacitor to
store a bit
• Leakage problems, requires
refreshing
• Used for dynamic data/program
storage
• Cheap & slow
• 4/6 transistor to save a single bit
• Volatile
• Fast but expensive
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Erasable ROMs
• Masked Programmable ROM
• Programmed by the manufacturer
• Programmable ROM (PROM)
• Can be programmed in the field via the programmer
• Erasable Programmable ROM (EPOM)
• Uses ultraviolet light to erase (through a quartz window)
• OTP refers to One-Time Programmable
• Electrically Erasable Programmable ROM (EEPROM)
• Each program location can be individually erased
• Expensive
• Requires programmer
• FLASH
• Can be programmed in-circuit (in-system)
• Easy to erase (no programmer)
• Only one section can be erased/written at a time (typically 64 bytes at a
time)
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Microprocessor-based Systems
I/O Ports
 The way the computer communicates with the outside world devices
 I/O ports are connected to Peripherals
 Peripherals are I/O devices
 Input devices
 Output devices
 Examples
 Printers and modems
 Keyboard and mouse
 Scanner
 Universal Serial Bus (USB)
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Microprocessor-based Systems
BUS
 The three components – MPU, memory, and I/O, are connected by a BUS
 Address Bus
 Consists of 16, 20, 24, or 32 parallel lines (wires) – unidirectional
 These lines contain the address of the memory location to read or
written
 Control Bus
 Consists of 4 to 10 (or more) parallel signal lines
 CPU sends signals along these lines to memory and to I/O ports
 Examples: Memory Read, Memory Write, I/O Read, I/O Write
 Data Bus
 Consists of 8, 16, or 32 parallel lines
 Bi-directional
 Only one device at a time can have its outputs enabled
 This requires the devices to have three-state output
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Expanded Microprocessor-Based System
 Note the direction
of the busses.
 What is the width
of the address bus?
 What is the value
of the Address bus
to access the first
register of the
R/WM?
Remember: 111 1111 1111 = 2^11=2K
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Now what about
Microcontrollers???
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First Microcontrollers
 IBM started using Intel processors in its PC
 Intel started its 8042 and 8048 (8-bit microcontroller) –
using in printers
 Apple Macintosh used Motorola 68000
 In 1980 Intel abandoned microcontroller business
 By 1989, Microchip was a major player in designing
microcontrollers
 PIC: Peripheral Interface Controller
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Embedded Controllers
Software Characteristics
 No operating systems
 Execute a single program, tailored exactly to the controller hardware
 Assembly language (vs. High-level language)
 Not transportable, machine specific
 Programmer needs to know CPU architecture
 Speed
 Program size
 Uniqueness
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Microcontroller Unit (MCU)
Block Diagram
 An integrated electronic computing
and logic device that includes three
major components on a single chip
 Microprocessor
 Memory
 I/O ports
 Includes support devices
 Timers
 A/D converter
 Serial I/O
 Parallel Slave Port
 All components connected by common
communication lines called the system
bus
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MCU Architecture
 RISC (Harvard)
 Reduced instruction set computer
 Simple operations
 Simple addressing modes
 Longer compiled program but faster to execute
 Uses pipelining
 CISC (Von Neuman)
 Complex instruction set computer
 More complex instructions (closer to high-level language
support)
Bench marks: How to compare MCUs together
MIPS: Million Instructions / second (Useful when the compilers are the same)
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Main 8-bit Controllers
 Microchip -PIC® Microcontrollers
 RISC architecture (reduced instruction set computer)
 Has sold over 2 billion as of 2002
 Cost effective and rich in peripherals
 Motorola – now Freescale
 CISC architecture
 Has hundreds of instructions
 Examples: 68HC05, 68HC08, 68HC11
 Intel – now Marvell
 CISC architecture
 Has hundreds of instructions
 Examples: 8051, 8052
 Many different manufacturerers: Philips, Dallas/MAXIM
Semiconductor, etc.
 Atmel
 RISC architecture (reduced instruction set computer)
 Cost effective and rich in peripherals
 AVR
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Software: From Machine to
High-Level Languages
(1 of 3)
 Machine Language: binary instructions
 All programs are converted into the
machine language of a processor for
execution
 Difficult to decipher and write
 Prone to cause many errors in writing
High-Level Language
Assembly Language
Machine Language
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Software: From Machine to
High-Level Languages
(2 of 3)
 Assembly Language: machine
instructions represented in
mnemonics
 Has one-to-one correspondence with
machine instructions
 Efficient in execution and use of
memory; machine-specific and not
easy to troubleshoot
High-Level Language
Assembly Language
Machine Language
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Software: From Machine to
High-Level Languages
(3 of 3)
 High-Level Languages: Such as
BASIC, C, and C++
 Written in statements of spoken
languages (such as English)
 Machine independent
 Easy to write and troubleshoot
 Requires large memory and less
efficient in execution
High-Level Language
Assembly Language
Machine Language
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
Data Format (8-bit)
(1 of 4)
 Unsigned Byte: All eight bits (Bit0
to Bit7) represent the magnitude
of a number

 Range 0 to FF in Hex and 0 to 255 in
decimal
Unsigned
Signed
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
Data Format (8-bit)
(2 of 4)
 Signed Byte: Seven bits (Bit0 to Bit6)
represent the magnitude of a number
 The eighth bit (Bit7) represents the sign of the
number. The number is positive when Bit7 is zero and
negative when Bit7 is one.
 Positive Numbers: 0 to 7F (0 to 127)
 Negative Numbers: 80 to FF (-1 to -128)
 All negative numbers are represented in 2’s
compliment
Unsigned
Signed
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
Data Format (8-bit)
(3 of 4)
 Binary Coded Decimal Numbers (BCD)
 8 bits of a number divided into groups of four, and
each group represents a decimal digit from 0 to 9
 Four-bit combinations from A through F in Hex are
invalid in BCD
 Example: 0010 0101 represents the binary coding of
the decimal number 25d which is different in value
from 25H
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
Data Format (8-bit)
(4 of 4)
 American Standard Code for Information
Interchange (ASCII)
 Seven-bit alphanumeric code with 128 combinations (00 to FF)
 Represents English alphabet, decimal digits from 0 to 9, symbols, and
commands
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Storing Bits in Memory
 We can store in different memory types
 EEPROM, FLASH, RAM, etc.
 In an 8-bit RAM
 Each byte is stored in a single
memory register
 Each word is stored in two memory
locations (registers)
 DATA 0x1234
 0x12 REG11 (High-order byte)
 0001 0010
 0x34REG10 (Low-order byte)
 0011 0100
Remember: -8 -> 111 1000 (in two’s complement)
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Design Examples …..
Microcontrollers vs. Microprocessors
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MPU-Based Time and Temperature System
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MCU-Based Time and Temperature System
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