Pololu Distance Sensor with Pulse Width Output, 50cm Max

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.

The relationship between measured distance d (in mm) and pulse width t (in µs) is as follows:

     d=3 mm4 µs⋅(t –1000 µs)${\displaystyle d=\frac{3\text{\hspace{0.17em}mm}}{4\text{\hspace{0.17em}µs}}\cdot (t –1000\text{\hspace{0.17em}µs})}$

     t=1000 µs+4 µs3 mm⋅d${\displaystyle t=1000\text{\hspace{0.17em}µs}+\frac{4\text{\hspace{0.17em}µs}}{3\text{\hspace{0.17em}mm}}\cdot d}$

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. The following graph shows the measured distances of five units versus their actual distances from a white paper target at several different ranges: