28123 Parallax Inc, 28123 Datasheet - Page 157

• Manufacturer Part Number: 28123
• Description: TEXT WHAT'S A MICROCONTROLLER
• Manufacturer: Parallax Inc
• Type: Programmingr

Specifications of 28123

• Style: Book
• Title: What's a Microcontroller?
• Contents: Whats a Microcontroller? Text
• Product: Microcontroller Accessories
• Core Processor: PIC16C57c
• Flash: 128 Bytes
• Operating Supply Voltage: 9 V
• Board Size: 31 mm x 16 mm
• Lead Free Status / RoHS Status: Not applicable / Not applicable

ACTIVITY #3: READING THE DIAL WITH THE BASIC STAMP
In Activity #1, a potentiometer was used as a variable resistor. The resistance in the
circuit varied depending on the position of the potentiometer’s adjusting knob. In
Activity #2, an RC-time circuit was used to measure different resistances. In this
activity, you will build an RC-time circuit to read the potentiometer, and use the BASIC
Stamp to take the time measurements. The capacitor you use will be very small, and the
time measurements will only take a few milliseconds. Even though the measurements
take very short durations of time, the BASIC Stamp will give you an excellent indication
of the resistance between the potentiometer’s A and W terminals.
Parts for Reading RC-Time with the BASIC Stamp
(1) Potentiometer – 10 kΩ
(1) Resistor – 220 Ω (red-red-brown)
(2) Jumper wires
(1) Capacitor – 0.1 µF shown in Figure 5-10
(1) Capacitor – 0.01 µF, also shown in Figure 5-10
(2) Jumper wires
√
√
Repeat the steps in the Example Program: PolledRcTimer.bs2 section, and
record your time measurements in Table 5-2.
Compare your time measurements to the ones you took earlier in Table 5-1.
How close are they to 1/3 the value of the measurements taken with the 3300
µF capacitor?
These capacitors do not have + and – terminals.
capacitors to a circuit without worrying about positive and negative terminals.
Table 5-2: Resistance and RC-time for C = 1000 µF
Resistance (Ω)
10 k
470
1 k
2 k
Measured Time (s)
You can safely connect these