Page 308 - Amphibionics : Build Your Own Biologically Inspired Robot

Amphibionics 07 3/24/03 9:13 AM Page 287
Chapter 7 / Turtletron: Build Your Own Robotic Turtle
The SRF04 range finder is a small printed circuit board (PCB) that
measures 1-3/4 3/4-inches, with two ultrasonic transducers
mounted on the front. The ranger requires a 5V power supply capa-
ble of handling roughly 50 mA of continuous output. One transduc-
er is used to send an ultrasonic signal, and the other transducer
receives the signal reflection from nearby objects. The SRF04 will
output a 100-microsecond to 18-millisecond detection pulse that is
proportional to range when a reflected signal is detected. Table 7.3
is a list of the parts that will be needed to add the sonar ranger. The
SRF04 range finder specifications are listed in Table 7.4.

Part Quantity Description TABLE 7.3
Parts Required for the
SRF04 ultrasonic ranger module 1 Sonar distance
Addition of the SRF04
measuring device Ultrasonic Range Finder
5-post male header connector 1 2.5-mm spacing
4-strand ribbon cable 1 8-1/2 inches
2-connector female header 2 2.5-mm spacing
1/16-inch thick aluminum 1 2-inches 4-inches
Hot glue — Hot glue and gun

Specification Value
TABLE 7.4
Voltage 5v
Table of Specifications
Current 30 mA Typical 50 mA for the SRF04
Frequency 40 kHz

Maximum range 3 meters
Minimum range 3 centimeters
Sensitivity Can detect a 3-cm diameter broom handle at 2 meters

Input trigger 10 µS minimum TTL level pulse
Echo pulse Positive TTL level signal, width proportional to range
Size 1-3/4 3/4-inches

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