28128 Parallax Inc, 28128 Datasheet - Page 11

• Manufacturer Part Number: 28128
• Description: KIT BASIC ANALOG/DIGI PARTS ONLY
• Manufacturer: Parallax Inc

Specifications of 28128

• Accessory Type: ADC, DAC
• Product: Microcontroller Accessories
• For Use With/related Products: BASIC Stamp® 2 and Board of Education
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Chapter 1: Analog Voltage and Binary States · Page 1
Chapter #1: Analog Voltage and Binary States
This series of experiments introduces analog and digital electronics. What does that
mean? In What’s a Microcontroller? we learned that analog is a “continuously variable
value”. Another way to think about it is that analog electronics is analogous to nature.
There are lots of continuously variable values in nature, such as motion, light level, and
sound. The position of a door as it swings open is a good example of a continuously
variable value. As a door swings from all the way closed to all the way open, it visits
every value in between. At one instant during its travel, it is 1/3 of the way open. At
another instant, it is 1/2 way open, and so on.
INTRODUCTION TO ANALOG AND DIGITAL
Digital simply means represented by digits. Think about how many times each day you
encounter analog values that are represented with digits. The temperature is 79.8 degrees.
The speed limit is 45 miles per hour, etc. Not surprisingly, digital electronics represents
values with digits.
The term digital is also used when referring to binary devices such as the circuitry that
makes a calculator work, the microprocessor in a computer, and the BASIC Stamp
microcontroller. It's true - they are all digital devices. Binary devices are digital devices
using two digits, 0 and 1.
The experiments in What’s a Microcontroller? introduced a variety of techniques for
interfacing with the outside world and other devices. These interfaces were mostly
binary. This series of experiments extends the capabilities of interfacing by introducing
several analog component interfaces and more component interface techniques.
In this first experiment, we'll build a circuit that produces an analog voltage at its output.
Remember that analog voltage is continuously variable. The circuit will be adjustable so
that it can produce an output anywhere between 0 and 5 volts. We'll also build a circuit
called a voltage follower that uses this analog voltage to drive an LED circuit.