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Microcontroller Designer's Overview
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Microcontrollers Are Everywhere
Used in everything from the simplest lawn watering controller to highly
sophisticated satellite systems, the microcontroller has become ubiquitous
and invisible. The average U.S. household has about 60 embedded microcontrollers.1
A 1999 BMW 7-Series has 65 microcontrollers.2 Over 5 billion
microcontrollers are added to the mix annually. Although the microcontrollers
in PCs are the most visible, they account for just 6% of the microcontroller
market.3
Where Microcontrollers Are Used
In the office, microcontrollers are used in computer keyboards, monitors,
printers, copiers, fax machines, and telephone-systems to name a few. In
your home, microcontrollers are used in microwave ovens, washers and dryers,
security systems, lawn sprinkler-station controllers, and music/video entertainment
components.
What Are Microcontrollers?
Microcontrollers are complete computer systems on a chip, typically combining
an arithmetic logic unit (ALU), memory, timer/counters, serial port, input/output
ports (I/O), and a clock oscillator.
Microcontrollers are used in applications requiring repetitive operations,
such as running the traffic light at an intersection. In this application,
the microcontroller's sole function is to turn lights on and off at predetermined
times.
Another example is a microwave oven. Let's examine how a microcontroller
functions while cooking a bag of popcorn in a microwave oven.
You open the door and put the bag of popcorn inside. You close the door
and push the button labeled "Popcorn." A few minutes later, a tone announces
the popcorn is done. What happened behind the scenes?
When you opened the door, the microcontroller sensed the door switch,
turned on the light and disabled the magnetron. The microcontroller continually
scans the keyboard. When you pushed the "Popcorn" button, the microcontroller
confirmed that the door was closed and began to count timing pulses, started
the motor for the turntable, set the power level of the magnetron, and
controlled the display. When the timer reached zero, the microcontroller
shut down the magnetron, stopped the turntable, and signaled you.
This is a simple example of a microcontroller application. Microcontrollers
are available with extra features such as analog-to-digital converters
(ADCs), pulse-width modulation (PWM), watchdog timers, controller area
network (CAN), and security functions.
Microcontroller Varieties
Maxim/Dallas Semiconductor offers four categories of microcontrollers:
secure, networking, mixed signal, and 8051 drop-in compatible.
| Microcontroller Type |
Description |
| Secure Microcontrollers |
High-speed 8051-compatible microcontrollers designed to resist all
levels of threat, including observation, analysis, and physical attack. |
| Networking Microcontrollers |
Network compatible 8051 microcontrollers with CAN, Ethernet, RS-232
serial, I2C, 1-Wire® net, and TINI™ (Tiny InterNet
Interface). |
| Mixed-Signal Microcontrollers |
High-speed 8051-compatible microcontrollers with ADC and PWM outputs. |
| 8051 Drop-in Compatible Microcontrollers |
High-speed 8051 pin and instruction-set compatible microcontrollers. |
A good starting point for information about these microcontrollers can
be found at maxim-ic.com/microcontrollers.
Application Information for Microcontroller Designers
Maxim/Dallas Semiconductor microcontroller application notes discuss many
issues the user may encounter while designing with this device. For instance,
a user might be unfamiliar with crystal oscillator requirements. A good
source of information would be the applications note, Specifying
Quartz Crystals. Maybe you're confused by the electrical requirements
of microcontrollers. The tutorial, Understanding
DC Electrical Characteristics of Microcontrollers may answer your questions.
Maxim/Dallas Semiconductor offers a comprehensive list of microcontroller
data sheets,
user's guides,
and application
notes.
1. "Embedded Microprocessors," Tom R. Halfhill, Computerworld,
August 28, 2000.
2. "Embedded
Processors by the Numbers," Jim Turley, Embedded Systems Programming.
3. "World Semiconductor Trade Statistics" blue book.
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