Initial report by Joo Youn Paek , 14, FEB, 2006
Parallax's PING)))ô ultrasonic sensor provides distance measurement. It measures distance using sonar; an ultrasonic (well above human hearing) pulse is transmitted from the unit and distance-to-target is determined by measuring the time required for the echo return. Output from the sensor is a variable-width pulse that corresponds to the distance to the target. The mearsurement distance is form 3 cm(1.2inches) to 3 meters (3.3yards). The activity status LED and the economic use of just 1 I/O pin make easier to use than other brand sonar sensor.
This sensor can be used for any applications that require measurements between moving or stationary objects. Naturally, robotics applications are very popular but we would also find this product to be useful in security systems. It can used as an infrared replacement,since it can detect transparent objects.
Electrical Characteristics Datasheet
- Supply Voltage - 5VDC
- Supply Current - 30 mA typ; 35 mA max
- Range - 3 cm ro 3 m(1.2in to 3.3 yrds)
- Input Trigger - positive TTL pulse, 115 uS to 18.5 ms
- Echo Hold-off - 750 uS from of trigger pulse
- Burst Frequency - 40 kHz for 200 uS
- Burst Indicator LED shows sensor activity
- Delay before next measurement - 200 uS
- Size - 22 mm H x 46 mm W x 16 mm D (0.84 in x 1.8 in x 0.6 in)
A male 3-pin header is built-in, supplying power, ground, and signal. It allows the sensor to be plugged into breadboard, which is easy to build fixed mounting. Signal pin transforms pulse in and out.
I connected signal pin to port.d 1 of the 18F452 microcontroller. Yet any digital pin will transform data succesfully. The microcontroller and the sensor shares the ground. Both receive power from the same supply but connected parallel.
Since it is for non-contect distance measurement, testing in a protected environment is important. The datasheet tells different sensing rage according to the shape of the target.
I tested mounting the sensor at the edge of a desk with 320cm x 270cm empty room in the front.
I tested four different targets. Closer the target, clear the value. ( for more details goto Joo Youn's Sensor Journal)
As slim cylinder was the best model to get rational data, I measured the sensing boundary with even slimmer cylinder. I made a long marker pen by attaching the marker pen at the end of 1-inch radius plastic pole. As searching the edge of the sensing area, I could draw the boundary of it.
The result didnít match exactly same dimension as the datasheet but the shape was similar. As the detecting area is narrow, detailed motion detaction is possble by using multiple sonar sensors.