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.

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 18, and `ECHO' is
    connected to GPIO 23.