Introduction to Embedded Systems

What is an Embedded System?

• Electronic devices that incorporate a microprocessor or microcontroller within their implementation.

• Microprocessor of embedded system is hidden from user.

• No Mouse, Kbd, monitor, etc.

Embedded Systems ApplicationsAerospace Navigation systems, automatic

landing systems, flight attitude controls, engine controls, space exploration (e.g.. The mars pathfinder)

Automotive Fuel injection control, passenger environmental controls, anti-locking braking systems, air bag controls, GPS mapping, cruise control

Children's toys Video games, MindStone system

Communications Satellites, network routers, switches, hubs

Embedded Systems ApplicationsComputer Peripherals Printers, scanners, keyboards,

displays, modems, hard disk drives, CD-ROM drives, USB

Home Dishwashers, microwave ovens, VCR’s, DVD, televisions, stereos, fire/security alarm systems, lawn sprinkler controls, thermostats, digital cameras, clock radios, cell phones

Industrial Elevator controls, surveillance systems, robots

Instrumentation Data collection, oscilloscopes, signal generators, signal analyzers, power supplies

Embedded Systems Applications

Medical CT, One touch glucose meter, almost all medical facility

Office Automation FAX machines, copiers, telephones,

Personal PDA’s, pagers, cell phones, video games, Ipod, MP3 players

Embedded Market

• Embedded:desktop = 100:1

• Average #embedded processors in the resident home estimated about 50

Embedded System

Embedded System

• CPU and Software

• Memory Storage: ROM, RAM, PROM, EPROM

• Input: knobs, buttons, probes, sensors, A/D communications signals, panels

• Output: LCD display, microwave radiation, A/D communication signals

• Outputs = functions (inputs, elapsed time, …)

Microprocessors in Embedded SystemsProcessor Bus

WidthLargest External Memory

Internal peripherals

Speed (MIPS)

Zilog Z8 family 8 64KB on others 2 timers 1

Intel 8051 family 8 64 KB program + 64 KB data

3 timers + 1 serial port

1

Intel 80188 8 1 MB 3 timers + 2 DMA channels

2

Intel 80386 family

16 64 MB 3 timers + 2 DMA channels + various others

5

Motorola 68000 family

32 4 GB Varying 10

Motorola Power PC family

32 64 MB Many 75

Common Design Criterion

• Production cost constraints• Processing power(limited)• Memory constraints(limited)• Development cost(low) • Number of units• Expected life time( may not be long)• Reliability

Design CriterionProcessor 4 or 8-bit 16-bit 32 or 64-bit

Memory < 16KB 64 KB~1 MB > 1 MB

Development Cost

< $100,000 $100,000 ~ $1,000,000

> $1,000,000

Production Cost

< $10 $10 ~ $1,000 > $1,000

# Units < 100 100 – 10,000 > 10,000

Expected lifetime

< years years decades

Reliability low Medium High

C for embedded software

• The most popular language for embedded systems ( over 80%)

• A high level language

• Compact, efficient code for almost all processors

• Both high-level and low-level features

• Direct hardware control, without losing the benefits of a high-level language

• Appropriate for 8-bit to 64-bit processors

• For systems with bytes, KB, MB of memory

Typical Hardware

• Microprocessor: execute code

• Memory: ROM, RAM, PROM, EPROM, Flash

• Embedded systems do not have the following

- a keyboard

- a screen

- a disk drive

- CD, speakers, microphones, diskettes, modems

• Embedded systems have: serial port, network interface, sensors, AD/DA

Design Goal of Embedded System

• Mission critical and life-threatening

• 24/7/365 and can’t reboot at all

• No human intervention

• Multitasking and scheduling

• Optimized I/O by Assembly Language

• Limits, Inaccuracies of Fixed Precision

• Consumer market: Minimize Manufacturing Cost

• Fast time to market required

• No chance for future modification

Design Goal of Embedded System

• Handle a lot of volume of data in a short period of time

• React to external events quickly

• Setting up equipment to test embedded software

• Without a screen or keyboard, finding out what the software is doing wrong

• Must be able to handle any situation without human intervention

• Memory is limited on embedded systems, and you must make the software and the data fit into whatever memory allows

Design Goal of Embedded System

• You will need special tools to get your software into embedded systems (burner)

• Portable systems must run on battery power, and the software in these systems must conserve power

• Embedded systems have a microprocessor and a memory. Some have a serial port or a network connection. They usually do not have keyboards, screens, or disk drives.