The Sharp distance sensors are a popular choice for many projects that require accurate distance measurements. This IR sensor is more economical and provides much better performance than other IR alternatives.
Theory of operationThe analog distance sensors use triangulation method and a small linear CCD array to compute the distance of objects in the field of view. In order to triangulate, a pulse of IR light is emitted by the emitter. The light travels out into the field of view and either hits an object or just keeps on going. In the case of no object, the light is never reflected, and the reading shows no object. If the light reflects off an object, it returns to the detector and creates a triangle between the point of reflection, the emitter and the detector.
The incident angle of the reflected light varies based on the distance to the object. The receiver portion of the IR rangers is a precision lens that transmits reflected light onto various portions of the enclosed linear CCD array based on the incident angle of the reflected light. The CCD array can then determine the incident angle, and thus calculate the distance to the object. This method of ranging is very immune to interference from ambient light and offers indifference to the color of the object being detected. The accuracy of distance depends on the resolution of CCD. The farther the object to be measured is, the higher the CCD resolution required.
GP2Y0A60SZ Analog Distance Sensor
The GP2Y0A60SZ analog distance sensor from Sharp offers a wide detection range of 4″ to 60″ (10 cm to 150 cm) and a high update rate of 60 Hz. As the name indicates, the distance is indicated by analog voltage in the OUT pin. The sensor module consists of a Sharp GP2Y0A60SZLF sensor installed on Pololu’s compact carrier board, which includes all of the external components required to make the sensor work and provides a 0.1″ pin spacing.
- EN – can be driven low to disable the IR emitter and put the sensor into a low-current stand-by mode. This pin is pulled high on the carrier board through a 10 kΩ pull-up resistor to enable the sensor by default.
- OUT – This pin provides analog output voltage corresponding to the distance measured. It can be connected to an analog-to-digital converter(ADC) for taking distance measurements, or the output can be connected to a comparator for threshold detection.
- VCC - +ve supply voltage
- GND - Ground
A 1×4 strip of 0.1″ header pins and a 1×4 strip of 0.1″ right-angle header pins are included in the package, which you can solder to the board for use with custom cables or solderless breadboards. You can even solder wires directly to the board itself for more compact installations. The board has a 0.125″ mounting hole suitable for M3 screws (not included). If you do not need the mounting hole, you can cut that part of the board off to reduce its size.
- Two modes of operation : 5V and 3V
- Operating voltage:
- 5V version : 2.7 V to 5.5 V
- 3V version : 2.7 V to 3.6 V
- Average current consumption : 33 mA (typical)
- Distance measuring range : 10 cm to 150 cm (4″ to 60″)
- Output type : analog voltage
- Output voltage differential over distance range:
- 5V version : 3.0 V (typical)
- 3V version : 1.6 V (typical)
- Update period : 16.5 ± 4 ms
- Enable pin can optionally be used to disable the emitter and save power
- Size without header pins : 33 mm × 10.4 mm × 10.2 mm (1.3″ × 0.41″ × 0.4″)
- Weight without header pins : 2.5 g
Modes of Operation GP2Y0A60SZ supports two operating modes : 5V and 3V.
- In 5V mode, the recommended operating voltage is 2.7 V to 5.5 V, and the output voltage differential over the full distance range is approximately 3 V, varying from around 3.6 V at 10 cm to 0.6 V at 150 cm. The main drawback of powering the 5V version at a lower voltage is that the output voltage will not exceed the supply voltage, so the effective minimum detection distance might increase (i.e. for distances that would result in output voltages above your supply voltage, the output will instead be capped at the supply voltage).
- In 3V mode, the recommended operating voltage is 2.7 V to 3.6 V, and the output voltage differential over the full distance range is approximately 1.6 V, varying from around 1.9 V at 10 cm to 0.3 V at 150 cm.
The sensor can be configured to operate in 5V mode or 3V mode. The following images clearly explain how to select each mode of operation.
The two modes differ in the presence or absence of a zero ohm resistor (the component location is marked by a rectangle on the silkscreen). You can convert a 5V version to 3V by removing the resistor, and you can convert a 3V version to 5V by shorting across the two pads.