The GP2D120 is the shortest-range Sharp analog distance sensor we carry, featuring a detection range of 1.5" to 12". The shorter range gives you higher resolution measurements, and the lower minimum detection distance makes this sensor great for detecting very close objects. The distance is indicated by an analog voltage, making this sensor very easy to use.
Note: We do not know when or if we will be able to get this part in stock again and currently consider this sensor to be discontinued. Please consider our other optical distance sensors as alternatives.
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 4 cm to 30 cm (1.5" to 12"); a plot of distance versus output voltage is shown below.
The GP2D120 uses a 3-pin JST connector that works with our 3-pin JST cables for Sharp distance sensors (not included) as shown in the top picture on the right. It is also simple 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.
Linearizing the output
The relationship between the sensor’s output voltage and the inverse of the measured distance is approximately linear over the sensor’s usable range. The GP2D120 data sheet (293k pdf) contains a plot of analog output voltage as a function of the inverse of distance to a reflective object. You can use this plot to convert the sensor output voltage to an approximate distance by constructing a best-fit line that relates the inverse of the output voltage (V) to distance (cm).
Alternative Sharp Distance Sensors
We carry two longer-range versions of this sensor as well: the Sharp GP2Y0A02YK0F analog distance sensor (20 – 150 cm) and the Sharp GP2Y0A21YK0F analog distance sensor (10 – 80 cm). These analog distance sensors all have identical packages and pin-outs, making it easy to swap one version for another should your application requirements change. We also sell a digital Sharp distance sensor, which has a lower minimum detection distance, quicker response time, lower current draw, and a much smaller package.
Note: The manufacturer recommends you insert a bypass capacitor of 10 uF or more between Vcc and GND near this sensor to stabilize your power supply line.
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