Parallax ToF Laser PING 2m Rangefinder : Data Sheet : Page 4

The pulse width is proportional to the distance, and does not significantly change with the

ambient temperature, pressure, or humidity.

To convert the pulse width from time, in µs, to mm, use the following equation:

Distance (mm) = Pulse Width (ms) × 171.5

To convert the pulse width from time, in µs, to inches, use the following equation:

Distance (inches) = Pulse Width (ms) × 6.752

Serial Data Mode

Serial data mode works at 9600 baud with a bidirectional TTL interface on a single I/O pin (SIG),

and can communicate with 3.3 V or 5 V TTL or CMOS microcontrollers. The SIG pin will idle high

in this mode, at the VIN voltage.

To switch from the default PWM mode to serial mode, drive the SIG pin low, then send three

high 100 µs pulses with 5 µs, or longer, low gaps between. This can be done by transmitting a

capital ‘I’ character.

Tip: For use with microcontrollers that do not support bidirectional serial, the LaserPING

module can be configured to wake-up in serial mode. In this case, only a single serial-rx input

is required at your microcontroller! Refer to the section “Enabling Serial on Start-up” below.

In Serial mode, LaserPING will constantly send new measurement data in ASCII format. The

value will be in millimeters, and followed by carriage return character (decimal 13). A new value

will be transmitted each time the sensor receives a valid reading, typically once every 45 ms.

Serial Value

Condition

50 to 2000

Highest accuracy measurement in millimeters

1 to 49

Reduced accuracy measurement in millimeters

2001 to 2046

2047

Reflection detected beyond 2046 millimeters

0 or 2222

Invalid measurement

(No reflection; target too close, too far, or too dark)

9998

Internal sensor error

9999

Internal sensor timeout

LaserPING Rangefinder Module (#28041)

v1.0 1/29/2018 Page 4 of 8