28123 Parallax Inc, 28123 Datasheet - Page 325

• 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

If you are using a 9 V battery, you can also compare the brightness of a different voltage
source, Vin. Vin is connected directly to the 9 V battery’s + terminal, and Vss is
connected directly to the battery’s negative terminal. Vdd is called regulated 5 V. That’s
about half the voltage of the 9 V battery.
Calculating the Current
The BASIC Stamp Manual has some rules about how much current it can supply to
circuits. If you don’t follow these rules, you may end up damaging your BASIC Stamp.
Vdd
Vss
√
√
√
√
√
√
R
LED
i
If you are not using a 9 V battery, stop here and skip to the Calculating the
Current section below. Otherwise, continue.
Start with the circuit shown in Figure F-1, but use a 1 kΩ resistor.
Make a note of how bright the LED is.
Disconnect power
Modify the circuit by disconnecting the resistor lead from Vdd and plugging it
into Vin.
When you plug the power back in, is the LED brighter? How much brighter?
DO NOT try the Vin experiment with a 220 or 470 Ω resistor, it will supply the LED with
more current than it is rated for.
R
1
R = 220
R = 470
R = 1 k
R = 2 k
R
1
2
3
4
2
R
3
Ω
Ω
Ω
Ω
R
4
P15
P14
P13
P12
P11
P10
P9
P8
P7
P6
P5
P4
P3
P2
P1
P0
X2
X3
Vdd
Vin
+
Vss
Figure F-1
LED Current Monitor