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Pololu Distance Sensor with Pulse Width Output, 130cm Max

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Pololu Distance Sensor with Pulse Width Output, 130cm Max

SKU: POLOLU-4071 Brand: Pololu

This small lidar-based distance sensor reports the distance of objects up to about 130 cm (50") away with a pulsed signal similar to a hobby servo control ...

$30.70 AUD, inc GST

$27.91 AUD, exc GST

Available with a lead time
Expect dispatch between May 21 and May 27

Quantity Discounts:

10-25 $27.07 (exc GST)
25+ $26.51 (exc GST)

This compact sensor makes it possible to measure the distance of objects up to about 130 cm (50") away using a simple digital pulse width interface (similar to a hobby servo control signal). 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 1 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.

A camera with no IR filter shows the infrared light emitted by a Pololu Digital Distance Sensor.

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

d=2 mm1 µs⋅(t –1000 µs)" role="presentation">d=2 mm1 µs·(t –1000 µs) $d = \frac{2 mm}{1 µs} \cdot (t - 1000 µs)$

t=1000 µs+1 µs2 mm⋅dt=1000 µs+1 µs2 mm·d $t = 1000 µs + \frac{1 µs}{2 mm} \cdot d$

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 130 cm will produce a 1.65 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 10 ms, depending on the proximity of the detected object.

The maximum detection range depends on object reflectivity and ambient lighting conditions. In Pololu's tests, the sensor was able to reliably detect a white sheet of paper out to its maximum range of 130 cm, and it could reliably detect a hand out to around 80 cm away. The following graph shows the measured distances of three units versus their actual distances from a variety of targets at several different ranges:

Please note that while this sensor can detect objects to within about 1 mm of the sensor face, the effective minimum distance it can measure is around 4 cm, so objects closer than 4 cm might result in an inaccurate measurement.

Specifications

Operating voltage: 3.0 V to 5.5 V
Current consumption: 30 mA (typical) when enabled, 0.4 mA when disabled
Maximum range: approximately 130 cm (50") (for high-reflectivity targets in good ambient conditions; lower-reflectivity targets or poor ambient conditions will reduce the maximum detection range)
Minimum range: 4 cm (for accurate measurement); < 1 mm (for detection)
Update rate: 100 Hz to 110 Hz (10 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" × 0.136" (21.6 × 8.9 × 3.5 mm); see the dimension diagram (193k pdf) for more information
Weight: 0.014 oz (0.4 g)

Using the sensor

Important note: This product might ship with a protective liner covering the sensor IC. The liner must be removed for proper sensing performance.

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 sensor outputs its digital pulses on the OUT pin. The low level of the pulses is 0 V, and the high level is VIN. A red LED on the back side of the board also lights whenever an object is detected (the closer the object, the brighter the LED).

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 neighboring surface-mount pad on the back side labeled “EN” on the silkscreen. The ENABLE pin is pulled up to VIN, enabling the sensor by default.

The board has one mounting hole intended for use with #2 or M2 screws.

Arduino program for reading pulse width output

This is a simple Arduino sketch that reads the output of the Pololu Distance Sensor with Pulse Width Output, 130cm Max and displays the measured distance in millimeters.

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// Example Arduino program for reading the Pololu Distance Sensor with Pulse Width Output, 130cm Max

// Change this to match the Arduino pin connected to the sensor's OUT pin.
const uint8_t sensorPin = 2;

void setup()
{
  Serial.begin(115200);
}

void loop()
{
  int16_t t = pulseIn(sensorPin, HIGH);

  if (t == 0)
  {
    // pulseIn() did not detect the start of a pulse within 1 second.
    Serial.println("timeout");
  }
  else if (t > 1850)
  {
    // No detection.
    Serial.println(-1);
  }
  else
  {
    // Valid pulse width reading. Convert pulse width in microseconds to distance in millimeters.
    int16_t d = (t - 1000) * 2;

    // Limit minimum distance to 0.
    if (d < 0) { d = 0; }

    Serial.print(d);
    Serial.println(" mm");
  }
}

micro:bit MakeCode program for reading pulse width output

Pololu have also created a MakeCode example program for the BBC micro:bit single-board computer that demonstrates how to read and convert the output of the Pololu Distance Sensor with Pulse Width Output, 300cm Max. The program’s output can be viewed in the MakeCode device console, which also plots the readings on a graph. You can open the program in the micro:bit MakeCode editor by clicking this link or the picture below.

Jumper settings (irs17a)

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 O 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. This sensor can be converted into any other irs17a version as listed in the following table. (For more information about how the different output types work, see the product pages for representative versions.)

Item #	Description	Maximum range*	Hysteresis	Resolution	Minimum update rate	Jumper settings (4321)
#4066	Digital output, 25cm	25 cm	50 mm	-	100 Hz	0000
#4067	Digital output, 50cm	50 cm	50 mm	-	100 Hz	0001
	Digital output, 75cm	75 cm	50 mm	-	100 Hz	0010
#4069	Digital output, 100cm	100 cm	50 mm	-	100 Hz	0011
	Digital output, any detect	~130 cm	-	-	100 Hz	0100
#4071	Pulse width output, 130cm max	~130 cm	-	1 mm (= 0.5 µs)	100 Hz (110 Hz max)	0101
	Digital output,125cm	125 cm	50 mm	-	30 Hz	1000
	Digital output,150cm	150 cm	50 mm	-	30 Hz	1001
	Digital output,175cm	175 cm	50 mm	-	30 Hz	1010
#4077	Digital output, 200cm	200 cm	50 mm	-	30 Hz	1011
	Digital output, any detect	~300 cm	-	-	30 Hz	1100
#4079	Pulse width output, 300cm max	~300 cm	-	2 mm (= 0.5 µs)	30 Hz (33 Hz max)	1101

* Effective range depends on object reflectivity and ambient lighting conditions.

Item numbers in this table indicate versions that Pololu offer for sale as standard products, but Pololu can manufacture the other versions on demand (or even make sensors with custom firmware for you). If you are interested in customization, please contact us.

The Pololu Digital Distance Sensor family

Pololu have several different versions of Pololu Digital Distance Sensors, all with the same dimensions and pinout:

Sensor	Maximum range¹	Minimum range	Minimum update rate	Jumper settings (4321)	PCB ID	Price
Digital output (does not provide distance measurement)
#4050: Digital output, 5cm	5 cm	< 5 mm	145 Hz	0000	irs16a	$12.95
#4052: Digital output, 10cm	10 cm	< 5 mm	115 Hz	0010
#4054: Digital output, 15cm	15 cm	< 5 mm	95 Hz	0100
#4066: Digital output, 25cm	25 cm	< 1 mm	100 Hz	0000	irs17a	$17.95
#4067: Digital output, 50cm	50 cm	< 1 mm	100 Hz	0001
#4069: Digital output, 100cm	100 cm	< 1 mm	100 Hz	0011
#4077: Digital output, 200cm	200 cm	< 1 mm	30 Hz	1011

Sensor	Maximum range¹	Minimum range²	Resolution	Minimum update rate	Jumper settings (4321)	PCB ID	Price
Pulse width output (provides distance measurement)
#4064: Pulse width output, 50cm max	~50 cm	1 cm	3 mm	50 Hz	1110	irs16a	$12.95
#4071: Pulse width output, 130cm max	~130 cm	4 cm	1 mm	100 Hz	0101	irs17a	$17.95
#4079: Pulse width output, 300cm max	~300 cm	4 cm	2 mm	30 Hz	1101	irs17a	$17.95

¹ Effective range depends on object reflectivity and ambient lighting conditions.
² Objects closer than the minimum distance can still be detected, but the measured distance might be inaccurate. The minimum detection range is < 5 mm for irs16a boards and < 1 mm for irs17a boards.

These are the output graphs for the digital output versions that just report if an object is in their detection range:

The output graph is a bit different for the versions that use a pulse width to encode the measured distance. The output for these versions is similar to hobby servo control signals and is shown below as a function of time:

Comparison to Sharp Digital Distance Sensors

These Pololu Digital Distance Sensors have the same form factor and pinout as Pololu's carrier boards for the Sharp/Socle GP2Y0D8x digital distance sensors. They are available in the same 5 cm, 10 cm, and 15 cm ranges, in addition to longer ranges of up to several meters. This means they can be used as replacements for these older modules, which are based on sensors from Sharp/Socle that are no longer in production, and the longer-range versions can serve as upgrades that provide enhanced detection and measurement capabilities. The sensors on these newer units are much thinner than the Sharp modules, so the zero-range point is approximately 7 mm closer to the PCB, and the beam angle of the newer units is wider. The pictures below show side-by-side comparisons of the two:

People often buy this product together with:

Pololu Distance Sensor with Pulse Width Output, 50cm Max

Pololu Distance Sensor with Pulse Width Output, 300cm Max

Dimensions

Size:	0.85" × 0.35" × 0.136"
Weight:	0.4 g

General specifications

Resolution:	1 mm
Maximum range:	130 cm¹
Sampling rate:	100 Hz²
Minimum operating voltage:	3.0 V
Maximum operating voltage:	5.5 V
Supply current:	30 mA³
Output type:	digital pulse width

Identifying markings

PCB dev codes:	irs17a
Other PCB markings:	0J13150

Notes:

1: This maximum is only achievable for high-reflectance objects in good ambient conditions; lower-reflectivity targets or poor ambient conditions will reduce the maximum range.
2: Minimum.
3: Typical average current draw when enabled; disabling via the EN pin reduces it to around 0.4 mA.

File downloads

Dimension diagram of the Pololu Digital Distance Sensors (irs17a) (193k pdf)
3D model of the Pololu Digital Distance Sensors (irs17a) (5MB step)
Drill guide for the Pololu Digital Distance Sensors (irs17a) (22k dxf)

This DXF drawing shows the locations of all of the board’s holes.

Recommended links

micro:bit MakeCode serial example for the Pololu Distance Sensor with Pulse Width Output, 130cm Max

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