Data Sheet

Communication Protocol
The sensor emits an infrared (IR) laser pulse which travels through the air, reflects off of objects
and then bounces back to the sensor. The LaserPING module accurately measures how long the
reflected laser pulse takes to return to the sensor, and converts this time measurement into
millimeters, with a 1 mm resolution. Your microcontroller queries the LaserPING module for
the latest measurement (which is refreshed about every 40 ms) and then receives the value
back on the same I/O pin, as either a variable-width pulse in PWM mode, or as ASCII characters
in serial mode.
PWM Mode
PWM default mode is designed to be code-compatible with PING))) Ultrasonic Distance Sensor
(#28015) code. It can communicate with 3.3 V or 5 V TTL or CMOS microcontrollers. PWM
Mode uses a bidirectional TTL pulse interface on a single I/O pin (SIG). The SIG pin will idle low,
and both the input pulse and echo pulse will be positive high, at the VIN voltage.
Host Device
Input Trigger Pulse
t
OUT
2 µs (min)
LaserPING
Sensor
Holdoff
t
HOLDOFF
750 µs
Return Pulse Minimum
t
IN-MIN
115 µs
Return Pulse Maximum
t
IN-MAX
15 ms
Delay before next
measurement
65 ms
Pulse width
Condition
115 to 290 µs
Reduced accuracy measurement
290 µs to 12 ms
Highest accuracy measurement
13 ms
Invalid measurement — target too close or too far
14 ms
Internal sensor error
15 ms
Internal sensor timeout
Copyright © Parallax Inc.
LaserPING Rangefinder Module (#28041)
v1.0 1/29/2018 Page 3 of 8