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Distance Sensor with Pulse Width Output, 50cm Max

by Pololu
SKU 3991
Sold out
£9.59 inc VAT
£7.99 ex VAT

This small lidar-based distance sensor reports the distance of objects up to about 50 cm (20″) away with a pulsed signal similar to a hobby servo control signal. A digital microcontroller pin can be used to time the length of each high pulse, which encodes the measured distance. The sensor works over an input voltage range of 3.0 V to 5.5 V, and the 0.1″ pin spacing makes it easy to use with standard solderless breadboards and 0.1″ perfboards.

It uses a short-range lidar module to precisely measure how long it takes for emitted pulses of infrared, eye-safe laser light to reach the nearest object and be reflected back, allowing for 3 mm resolution. As long as the sensor is enabled, it takes continuous distance measurements and encodes the ranges as the widths of high pulses, which can then be timed by a microcontroller using a single digital input.

The timing uncertainty is approximately ±5%. As objects approach the sensor, the output pulse width will approach 1.0 ms, while an object detected at 50 cm will produce a 1.667 ms pulse width. The sensor uses a pulse width of 2.0 ms to indicate no detection. The pulse period T ranges from around 9 ms to 20 ms, depending on the proximity of the detected object. The maximum detection range depends on object reflectivity and ambient lighting conditions. In our tests, the sensor was able to reliably detect a white sheet of paper out to around 50 cm away, and it could reliably detect a hand out to around 30 cm away.

  • Operating voltage: 3.0 V to 5.5 V
  • Current consumption: 30 mA (typical) when enabled, 0.4 mA when disabled
  • Maximum range: approximately 50 cm (20″) (for high-reflectivity targets in good ambient conditions; lower-reflectivity targets or poor ambient conditions will reduce the maximum detection range)
  • Update rate: 50 Hz to 110 Hz (20 ms to 9 ms period)
  • Field of view (FOV): 15° typical; can vary with object reflectance and ambient conditions
  • Output type: digital pulse width
  • Dimensions: 0.85″ × 0.35″ × 0.122″ (21.6 × 8.9 × 3.1 mm)
  • Weight: 0.014 oz (0.4 g)
Dimension Diagram

Using the Sensor

Three connections are necessary to use this module: VIN, GND, and OUT. These pins are accessible through a row of 0.1″-pitch through holes, which work with standard 0.1″ (2.54 mm) male headers and 0.1″ female headers (available separately). The VIN pin should be connected to a 3 V to 5.5 V source, and GND should be connected to 0 volts. The OUT pin drives low (0 V) when an object is being detected and it drives high (to the VIN level) when an object is not being detected. It is weakly pulled high when the sensor is disabled or waiting for its first reading to complete after power-up. A red LED on the back side of the board also lights whenever an object is detected.

The board has an optional ENABLE pin that can be driven low to put it into a low-power state that consumes approximately 0.4 mA. This pin can be accessed through a via or its neighbouring surface-mount pad on the back side labelled “EN” on the silkscreen. The ENABLE pin is pulled up to VIN, enabling the sensor by default. The board features four surface-mount configuration jumpers that determine its operation mode. Different versions of the Pololu Digital Distance sensors ship with the appropriate jumpers pre-populated with 0 Ω resistors. These resistors can be desoldered from the populated spots or solder bridges can be added across the unpopulated spots to convert one sensor version into another.