Nerves_Hcsr04

A library to interface with the HC-SR04 ultrasonic distance sensor.

⚠️ Linux based systems are not fast enough to keep up with the short modulation frequency of a GPIO based interfaces like the HC-SR04.

If you need more accurate measurements, especially over a longer period of time, you should look for an I2C based distance sensor.

Wiring

The HC-SR04 sensors has 4 pins. VCC and GND are a given.

ECHO is a input pin receiving the signal modulation when the measurement is completed. TRIG is a output pin triggering the measurement process.

The package can be installed by adding nerves_hcsr04 to your list of dependencies in mix.exs:

def deps do
  [
    {:nerves_hcsr04, "~> 0.1.0"}
  ]
end

{:ok, pid} = Hcsr04.start_link([trigger: 18, echo: 24])
distance_in_mm = Hcsr04.read(pid)

Once published, the docs can be found at https://hexdocs.pm/hcsr04.