28123 Parallax Inc, 28123 Datasheet - Page 274

• 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 #2: INTRODUCING THE DIGITAL POTENTIOMETER
In this activity, you will replace the manually adjusted potentiometer with an integrated
circuit potentiometer that is digitally adjusted. You will then program the BASIC Stamp
to adjust the digital potentiometer, which will in turn adjust the LED’s brightness in the
same way the manual potentiometer did in the previous activity.
P8
√
√
√
What’s the difference between this and connecting an LED circuit to an I/O pin?
BASIC Stamp I/O pins have limitations on how much current they can deliver. Transistors
have limitations too, but they are much higher. In the Industrial Control Student Guide, a
transistor is used to drive a small DC fan. It is also used to supply large amounts of current
to a small resistor that is used as a heating element. Either of these two applications would
draw so much current that they would quickly damage the BASIC Stamp, but the transistor
takes it in stride.
Build the circuit shown in Figure 9-4.
Write a program that sends high and low signals to P8 twice every second.
HINT: LedOnOff.bs2 from Chapter #2 needs only to be modified to send
high/low signals to P8 instead of P3. Remember to save it under a new name
before making the modifications.
Run the program and verify that it gives you on/off control of the LED.
100
100
kΩ
kΩ
Vdd
Vss
LED
P15
P14
P13
P12
P11
P10
P9
P8
P7
P6
P5
P4
P3
P2
P1
P0
X2
X3
Vdd
Vin
Vss
Figure 9-4
Circuit that
Gives BASIC
Stamp
Transistor
On/Off Control