28129 Parallax Inc, 28129 Datasheet - Page 23

• Manufacturer Part Number: 28129
• Description: TEXT BASIC ANALOG & DIGITAL
• Manufacturer: Parallax Inc
• Type: Programmingr

Specifications of 28129

• Style: Book
• Title: Basic Analog and Digital
• Contents: Basic Analog and Digital Text
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Not applicable / Not applicable

The Output
As you adjust the potentiometer, note how the LED at the voltage follower's analog
output can vary in brightness. Meanwhile the LED circuit driven by P12 either turns on
or off. This characterizes the difference between analog voltage and digital (binary)
voltage.
The output displayed in the Debug Terminal should resemble the output shown in Figure
1-9. The state of P7 will either be 0 or 1. Correspondingly, the LED circuit driven by P12
will either be off or on.
Adjust the potentiometer until you have found the threshold voltage. You will know
when you've found it because the Debug Terminal will indicate that the state of P7 skips
back and forth between 0 and 1 with just the slightest adjustment of the pot. Note the
position of the potentiometer. After we build a DC voltmeter in Chapter #3, we can find
out how close we are to 1.4 volts, which is the actual threshold voltage of a BASIC
Stamp I/O pin when it's functioning as an input.
Figure 1-9
Debug Terminal
Output for Program