28128 Parallax Inc, 28128 Datasheet - Page 97

• 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 4: Basic Digital to Analog Conversion· Page 87
Why did I learn it?
There are many different “real world” circuits that require some sort of analog voltage.
For example, when you listen to a compact disc, you’re listening to sounds that started as
analog signals from a microphone. Then the signal underwent the A/D process when it
was digitized. The CD player then performs the D/A conversion using the digital
information on the CD. The analog signal is amplified and played on a speaker.
When designing commercial products, it is your responsibility to determine the most
appropriate (and cost effective) method to accomplish a given task. A resistive D/A
converter is a very economical method to get an analog voltage from a digital device.
How can I apply this?
You've just built a variable voltage source and a digital voltmeter on the same
breadboard. You also used some PBASIC Programming techniques to obtain information
about the converter using a voltage sweep. One application of this can be testing circuits,
but there are many others. In Chapter #5, we'll see how PBASIC can be used to control
the volume of tones emitted by a speaker. In Chapter #7, we'll use D/A conversion to
control the brightness of an LED transmitting a signal to a photoresistor.
The applications for D/A and A/D interfaces combined with a microcontroller are only
limited by one's imagination. These techniques can be applied to automated houses,
irrigation systems, rocket guidance systems, and robotics to name a few. Control systems
engineering is a field of study within electrical engineering that you might look into if
you find designing such systems interesting.