hcsr04

Documentation

Overview

Package hcsr04 : Library for working with the Ultrasonic Ranging Module HC - SR04

From the datasheet: Ultrasonic ranging module HC - SR04 provides 2cm - 400cm non-contact measurement function, the ranging accuracy can reach to 3mm. The modules includes ultrasonic transmitters, receiver and control circuit. The basic principle of work:

(1) Using IO trigger for at least 10us high level signal,
(2) The Module automatically sends eight 40 kHz and detect whether there is a

pulse signal back.

(3) IF the signal back, through high level, time of high output IO duration is

the time from sending ultrasonic to returning. Test distance = (high level time×velocity of sound (340M/S) / 2,

You can calculate the range through the time interval between sending trigger signal and receiving echo signal. Formula: uS / 58 = centimeters or uS / 148 =inch; or: the range = high level time * velocity (340M/S) / 2; we suggest to use over 60ms measurement cycle, in order to prevent trigger signal to the echo signal.

Index

• type HCSR04
  • func NewHCSR04(echoPin int, triggerPin int) HCSR04
  • func (sensor *HCSR04) Measure() float64

Types

type HCSR04

type HCSR04 struct {
	EchoPin    rpio.Pin
	TriggerPin rpio.Pin
}

HCSR04 : Model to keep track the GPIO pins to use

func NewHCSR04

func NewHCSR04(echoPin int, triggerPin int) HCSR04

NewHCSR04 : Sets up a new HC-SR04 sensor

Uses the BCM number system

func (*HCSR04) Measure

func (sensor *HCSR04) Measure() float64

Measure : Takes a measurement then returns the distance in centimeter

Sensor has a resolution of 0.3cm. Returing the results of the calulation. Leaving the formatting of the number to the calling code.