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.
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