The Sharp distance sensors are a popular choice for many projects that require accurate distance measurements. This IR sensor is more economical than sonar rangefinders, yet it provides much better performance than other IR alternatives. Interfacing to most microcontrollers is straightforward: the single analog output can be connected to an analog-to-digital converter for taking distance measurements, or the output can be connected to a comparator for threshold detection. The detection range of this version is approximately 10 cm to 80 cm (4 to 32).
The GP2Y0A21 uses a 3-pin JST PH connector that works with our 3-pin JST PH cables for Sharp distance sensors (not included), as shown in the upper picture on the right. These cables have 3-pin JST connectors on one end and are available with pre-crimped male pins, pre-crimped female pins, and with unterminated wires on the other end. It is also possible to solder three wires to the sensor where the connector pins are mounted (see the lower picture to the right). When looking at the back, the three connections from left to right are power, ground, and the output signal.
Feature summary
Operating voltage: 4.5 V to 5.5 V Average current consumption: 30 mA (note: this sensor draws current in large, short bursts, and the manufacturer recommends putting a 10 F capacitor or larger across power and ground close to the sensor to stabilize the power supply line) Distance measuring range: 10 cm to 80 cm (4 to 32) Output type: analog voltage Output voltage differential over distance range: 1.9 V (typical) Update period: 38 10 ms Size: 44.5 mm 18.9 mm 13.5 mm (1.75 0.75 0.53) Weight: 3.5 g (0.12 oz)
Linearizing the output
The relationship between the sensors output voltage and the inverse of the measured distance is approximately linear over the sensors usable range. The GP2Y0A21YK datasheet (374k pdf) con