Home Chapter 17 Maxuino/Arduino ultrasonic sensor
Maxuino/Arduino ultrasonic sensor


PIR infrared sensor

Passive infrared (PIR) sensors sense by imaging movement. They first image a stable amount of infrared and then look for a change in that quantity of infrared. When you pass someone’s porch and the light comes on at night these sensors are switching on AC spotlights. they also make these in 5 volt packages and can interface directly to your microcontroller and require only one input/output line.

The k76 is available from Taiwan or also available from Parallax is an excellent sensor that has a range of a few inches to nine feet away. They are easy to use though they are not super fast in response time. 


PIR with the lens off


PIR sensors are not suitable for moving platforms, as they will continually sense their own movement when the platform is moving. However, they are robust, solid-state devices and are relatively inexpensive.

These can be turned into shotgun sensors to sense a narrow beam or you can paint out various FRESNEL windows on the sensor to tune sweat spots of where in the 9 foot sensing range it will activate. (Chapter 9).

The GP2DXX, direct infrared ranging distance sensors.

The GP2DXX sensors are versatile active infrared sensors that send out a pulse modulated beam of light and look for a triangulated beam back. They offer precision lenses which allows to be be accurate. This line of sensors can give one bit outputs or can sense a variety of distances from 4-216 inches.


These  sensors takes readings only when requested and can report distances between 4--30 inches so you can create a feedback loop between distance and interactive action.

I like the GP2Y0D02YK as it is a one bit sensor and works very well for quick response times and sensing from 4-32 inches.




The GP2Y0A700K can sense out to 216 inches and down to 40 inches and would allow you to have different things happening as people approached your work from a distance. Keep in mind that with this sensor you may be tying up your processor in reading values from the sensor, so for slower processors you are better off using a one bit sensor to allow interaction and activation of things like motors. Best source for these is Acroname.com




 This chart from Acroname indicated which sensor to choose for a variety of distances. 


QTI sensor infrared transmitter/receiver module


The QTI sensor available from Parallax, is a three pin, close range infrared transmitter/receiver module that has many neat applications. It can be incorporated into line following robots, used as an edge detector, or even as an electronic eye to sense varying shades of grayscale. The QTI features a QRD1114 reflective IR sensor manufactured by Fairchild Semiconductor which is comprised of an IR led transmitter and a matched NPN phototransistor receiver.


QTI Sensor


The phototransistor inside the QRD1114 allows the QTI to function as a digital switch or as a ratio metric analog sensor. This sensor allows the possibility for a black/white and gray scale sensing.

Ultrasonic distance sensor

Ultrasonic sensors work by bouncing a 40 k Hz frequency sound off objects and waiting for the return pulse modulated frequency. They can communicate with the stamp directly providing a series of numbers created in relation to the distance from the object being sensed. This sensor functions by transmitting ultrasonic chirps and measuring the time it takes to "hear" the chirp echo back.

Output from the sensor is a variable-width pulse, which will vary in proportion to the distance to the object or person being sensed. Refer to the Parallax web site for the circuit hookup to the BS2.

A wool sweater and piece of felt will absorb more sound than a piece of plywood for instance so the sensing distance will vary based on the material or object being looked for as well as it physical size.


 Ultrasonic sensor



The Ping from Parallax is capable of sensing to 3 meters. Ping requires only two I/O pins to interface to the BASIC stamp.

Bats use a 40 k Hz signal but with hearing so acute they can navigate through two pieces of silk thread inches apart. [2]