NAME RPi::HCSR04 - Interface to the HC-SR04 ultrasonic distance measurement sensor on the Raspberry Pi SYNOPSIS use RPi::HCSR04; my $trig_pin = 23; my $echo_pin = 24; my $sensor = RPi::HCSR04->new($trig_pin, $echo_pin); my $inches = $sensor->inch; my $cm = $sensor->cm; my $raw = $sensor->raw; ... DESCRIPTION Easy to use interface to retrieve distance measurements from the HC-SR04 ultrasonic distance measurement sensor. Requires wiringPi to be installed. TIMING WITHIN A LOOP This software does no timing whatsoever; it operates as fast as your device will allow it. This often causes odd results. It's recommended that if you put your checks within a loop, to sleep for at least two milliseconds (`0.02'). You can use `select(undef, undef, undef, 0.02);', or `usleep()' from Time::HiRes. VOLTAGE DIVIDER The HC-SR04 sensor requires 5V input, and that is returned back to a Pi GPIO pin from the `ECHO' output on the sensor. The GPIO on the Pi can only handle a maximum of 3.3V in, so either a voltage regulator or a voltage divider must be used to ensure you don't damage the Pi. Here's a diagram showing how to create a voltage divider with a 1k and a 2k Ohm resistor to lower the `ECHO' voltage output down to a safe ~3.29V. In this case, `TRIG' is connected to GPIO 23, and `ECHO' is connected to GPIO 24. METHODS new Instantiates and returns a new RPi::HCSR04 object. Parameters: $trig Mandatory: Integer, the GPIO pin number of the Raspberry Pi that the `TRIG' pin is connected to. $echo Mandatory: Integer, the GPIO pin number of the Raspberry Pi that the `ECHO' pin is connected to. inch Returns a floating point number containing the distance in inches. Takes no parameters. cm Returns a floating point number containing the distance in centemetres. Takes no parameters. raw Returns an integer representing the return from the sensor in raw original form. Takes no parameters. REQUIREMENTS * wiringPi must be installed. * You must regulate the voltage from the `ECHO' pin down to a safe 3.3V from the 5V input. See VOLTAGE DIVIDER for details. AUTHOR Steve Bertrand, `<steveb at cpan.org>' LICENSE AND COPYRIGHT Copyright 2017 Steve Bertrand. This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License. See http://dev.perl.org/licenses/ for more information.