Introduction to Microcontrollers
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
1
Microcontrollers
• Single-chip computer, with
memory and I/O
– Used for embedded systems
• Embedded means
– Designed for a specific task
– May need to control hardware in
real-time
– Often is built into the device it is
controlling
– May have little or no user interface
The average person
interacts with 150
microcontrollers per day!
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
2
A “short list” of embedded systems
Anti-lock brakes
Auto-focus cameras
Automatic teller machines
Automatic toll systems
Automatic transmission
Avionic systems
Battery chargers
Camcorders
Cell phones
Cell-phone base stations
Cordless phones
Cruise control
Curbside check-in systems
Digital cameras
Disk drives
Electronic card readers
Electronic instruments
Electronic toys/games
Factory control
Fax machines
Fingerprint identifiers
Home security systems
Life-support systems
Medical testing systems
Modems
MPEG decoders
Network cards
Network switches/routers
On-board navigation
Pagers
Photocopiers
Point-of-sale systems
Portable video games
Printers
Satellite phones
Scanners
Smart ovens/dishwashers
Speech recognizers
Stereo systems
Teleconferencing systems
Televisions
Temperature controllers
Theft tracking systems
TV set-top boxes
VCR’s, DVD players
Video game consoles
Video phones
Washers and dryers
And the list goes on and on
Microcomputer Architecture and Interfacing
Colorado School of Mines
From: Embedded System Design: A
Unified Hardware/Software Introduction,
by Vahid and Givargis, Wiley 2002.
Professor William Hoff
3
An embedded system example -- a digital
camera
Digital camera chip
CCD
CCD preprocessor
Pixel coprocessor
D2A
A2D
lens
JPEG codec
Microcontroller
Multiplier/Accum
DMA controller
Memory controller
•
•
•
Display ctrl
ISA bus interface
UART
Single-functioned -- always a digital camera
Tightly-constrained -- Low cost, low power, small, fast
Reactive and real-time -- only to a small extent
Microcomputer Architecture and Interfacing
Colorado School of Mines
LCD ctrl
From: Embedded System Design: A
Unified Hardware/Software Introduction,
by Vahid and Givargis, Wiley 2002.
Professor William Hoff
4
Microcontroller vs Microprocessor
Evolution
• Moore’s Law - # transistors / chip doubles every 1.5 to 2 years
• Trends in general purpose microprocessors
•
•
•
Larger data word sizes
Parallelism – pipelining, multiple processor cores
Larger arithmetic logic units with floating point capability
• Trends in microcontrollers
•
More built-in capability :
–
–
–
•
More I/O ports
Communications interfaces such as USB and CAN-bus
More timer functions
The idea is to decrease the number of chips needed to implement an
embedded system
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
5
HCS12 Microcontroller
• Serial
communications
• Pulse-width
modulation
outputs
• A/D, D/A
• Timers
• Pulse counters
• CAN bus, IIC bus
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
Embedded System Design
• Functionality may be implemented in hardware (circuit), or
software (microcontroller), or both ... which to use?
– Example: a multiply-accumulate circuit
• Tradeoffs and metrics
– Unit cost
• The monetary cost of manufacturing each copy of the system
– NRE cost (Non-Recurring Engineering cost)
• The one-time monetary cost of designing the system
– Performance
• The execution time or throughput of the system
– Size, power
– Flexibility
• The ability to change the functionality of the system without incurring heavy
NRE cost
Others?
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
7
Summary
• A microcontroller is a single chip computer, used in
embedded systems
• It includes hardware elements to make it easy to
interface to devices
• Microcontrollers are very common and are used in many
products
• They are a good design alternative to implementing
functionality in in hardware (i.e., a circuit)
Microcomputer Architecture and Interfacing
Colorado School of Mines
Professor William Hoff
8