28123 Parallax Inc, 28123 Datasheet - Page 153

• 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

Polling the RC-Time Circuit with the BASIC Stamp
Although a stopwatch can be used to record how long it takes the capacitor’s charge to
drop to a certain level, the BASIC Stamp can also be programmed to monitor the circuit
and give you a more reliable time measurement.
Example Program: PolledRcTimer.bs2
P7
√
√
P15
P14
P13
P12
P11
P10
P9
P8
P7
P6
P5
P4
P3
P2
P1
P0
R
Enter and run PolledRcTimer.bs2.
Observe how the BASIC Stamp charges the capacitor and then measures the
discharge time.
4
X2
X3
3300 µF
R
220
3
Vdd
Ω
R
2
Vin
R
1
Vss
Vss
-
+
R
i
R = 470
R = 1 k
R = 2 k
R = 10 k
1
2
3
4
Ω
Ω
Ω
Ω
Figure 5-9
Wiring Diagram for
Figure 5-8
Make sure that the
negative lead of the
capacitor is connected
on your board the same
way it is shown in this
figure, with the negative
lead connected to Vss.
Figure 5-8
Schematic for Viewing
RC-time Voltage Decay
Four different resistors
will be used as R
shown in the schematic.
First, the schematic will
be built and tested with
R
k
Ω
i
= 470
, etc.
Ω
, then R
i
i
= 1