Hcsr04 (Nerves_Hcsr04 v0.1.0) View Source
A module to interface with the HC-SR04 ultrasonic distance sensor.
WARN: Linux based systems are not fast enough to keep up with the short frequency of modulation based GPIO interfaces like the HC-SR04.
If you need more accurate measurements, especially over time, you should favour 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.
Link to this section Summary
Functions
Returns a specification to start this module under a supervisor.
Reads the distance in millimeters.
Starts the Hcsr04 process linked to the current process.
Link to this section Functions
Returns a specification to start this module under a supervisor.
See Supervisor
.
Reads the distance in millimeters.
Examples
iex> Hcsr04.read(pid)
154.2352463
Starts the Hcsr04 process linked to the current process.
Options
:trigger
- GPIO pin number for trigger pin:echo
- GPIO pin number for echo pin