28029 Parallax Inc, 28029 Datasheet - Page 54

• Manufacturer Part Number: 28029
• Description: KIT PARTS SMART SENSORS W/TEXT
• Manufacturer: Parallax Inc

Specifications of 28029

• Accessory Type: Parts Kit
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: BASIC Stamp® or Javelin Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant
• Other names: 28029PAR

Page 42 · Smart Sensors and Applications
The BASIC Stamp
from the Ping))) sensor lasted. This time measurement is how long it took sound to travel
to the object and back. Using this measurement and the speed of sound in air, you can
make your program calculate the object's distance in centimeters, inches, feet, etc.
ACTIVITY #1: MEASURING ECHO TIME
In this activity, you will test the Ping))) sensor and verify that it gives you echo time
measurements that correspond to an object's distance.
Parts Required
(1) Ping))) Ultrasonic Distance Sensor
(3) Jumper Wires
All you'll need is a Ping))) sensor and three jumper wires to make it work. The Ping)))
sensor has protection against programming mistakes (and wiring mistakes) built-in, so
there's no need to use a 220 Ω resistor between P15 and the Ping))) sensor's SIG terminal.
Ping))) Sensor Circuit
Figure 2-3 shows a schematic and wiring diagram for testing the Ping))) sensor.
√
Build the circuit.
The Ping))) sensor's chirps are not audible because 40 kHz is ultrasonic.
What we consider sound is our inner ear's ability to detect the variations in air pressure
caused by vibration. The rate of these variations determines the pitch of the tone. Higher
frequency tones result in higher pitch sounds and lower frequency tones result in lower pitch
tones.
Most people can hear tones that range from 20 Hz, which is very low pitch, to 20 kHz, which
is very high pitch. Subsonic is sound with frequencies below 20 Hz, and ultrasonic is sound
with frequencies above 20 kHz. Since the Ping))) sensor's chirps are at 40 kHz, they are
definitely ultrasonic, and not audible to people.
PULSIN
command uses a variable to store how long the high signal