Chris Powers / HCSR04

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

HCSR04.h@2:daacb9d21d73, 2020-06-03 (annotated)

Committer:
Powers
Date:
Wed Jun 03 17:05:41 2020 +0000
Revision:
2:daacb9d21d73
Parent:
1:6f9e41e319ad 
Version 0.3

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Powers 0:a3bc6812cccb 1 //-------------------------------------
Powers 0:a3bc6812cccb 2 // Short Example how to use this class:
Powers 2:daacb9d21d73 3 // [returns Distance in cm(float)]
Powers 0:a3bc6812cccb 4 //-------------------------------------
Powers 0:a3bc6812cccb 5 /*
Powers 0:a3bc6812cccb 6 #include "mbed.h"
Powers 0:a3bc6812cccb 7 #include "HCSR04.h"
Powers 0:a3bc6812cccb 8
Powers 0:a3bc6812cccb 9 Serial pc(USBTX, USBRX, 115200);
Powers 0:a3bc6812cccb 10 HCSR04 sensor(D9, D8);
Powers 0:a3bc6812cccb 11
Powers 0:a3bc6812cccb 12 int main(void)
Powers 0:a3bc6812cccb 13 {
Powers 0:a3bc6812cccb 14 pc.printf("\nHCSR04 - Interrupt\n");
Powers 0:a3bc6812cccb 15 sensor.startSensor(2);
Powers 0:a3bc6812cccb 16 while(1)
Powers 0:a3bc6812cccb 17 {
Powers 0:a3bc6812cccb 18 if(sensor.checkUpdate())
Powers 0:a3bc6812cccb 19 {
Powers 2:daacb9d21d73 20 pc.printf("Distance: %.2fcm \n", sensor.getDistance());
Powers 0:a3bc6812cccb 21 }
Powers 0:a3bc6812cccb 22 }
Powers 0:a3bc6812cccb 23 return 0;
Powers 0:a3bc6812cccb 24 }
Powers 0:a3bc6812cccb 25 */
Powers 0:a3bc6812cccb 26 #ifndef HCSR04_H
Powers 0:a3bc6812cccb 27 #define HCSR04_H
Powers 0:a3bc6812cccb 28
Powers 0:a3bc6812cccb 29 #include "mbed.h"
Powers 0:a3bc6812cccb 30
Powers 0:a3bc6812cccb 31
Powers 0:a3bc6812cccb 32 class HCSR04
Powers 0:a3bc6812cccb 33 {
Powers 0:a3bc6812cccb 34 private:
Powers 0:a3bc6812cccb 35 // Trigger PIN - to write LOW and HIGH
Powers 0:a3bc6812cccb 36 DigitalOut trigger;
Powers 0:a3bc6812cccb 37 // ECHO PIN - to start Function after rising/falling flank
Powers 0:a3bc6812cccb 38 InterruptIn echo;
Powers 0:a3bc6812cccb 39 // Ticker object to periodicly start the measurement
Powers 0:a3bc6812cccb 40 Ticker execute;
Powers 0:a3bc6812cccb 41 // Timeout to write LOW to Trigger pin after 10 microseconds
Powers 0:a3bc6812cccb 42 Timeout go_low;
Powers 0:a3bc6812cccb 43 // Timer to measure the time between the sonic burst goes out and in again
Powers 0:a3bc6812cccb 44 Timer get_time;
Powers 0:a3bc6812cccb 45 // Variables for the update status and the the distance in microseconds
Powers 0:a3bc6812cccb 46 volatile float distance_us;
Powers 0:a3bc6812cccb 47 volatile bool update;
Powers 0:a3bc6812cccb 48
Powers 0:a3bc6812cccb 49 // Called by TICKER object to periodicly write HIGH to TRIGGER PIN
Powers 0:a3bc6812cccb 50 void sendHigh(void);
Powers 0:a3bc6812cccb 51 // Called by TIMEOUT Object to set TRIPPER PIN LOW again
Powers 0:a3bc6812cccb 52 void sendLow(void);
Powers 0:a3bc6812cccb 53 // Called by interrupt - rising flank on ECHO PIN
Powers 0:a3bc6812cccb 54 void startTimer(void);
Powers 0:a3bc6812cccb 55 // Called by interrupt - falling flank on ECHO PIN
Powers 0:a3bc6812cccb 56 void stopTimer(void);
Powers 0:a3bc6812cccb 57
Powers 0:a3bc6812cccb 58 public:
Powers 0:a3bc6812cccb 59 // Constructor
Powers 0:a3bc6812cccb 60 HCSR04(PinName _trigger, PinName _echo):trigger(_trigger), echo(_echo)
Powers 0:a3bc6812cccb 61 {
Powers 0:a3bc6812cccb 62 // Attach member functions to InterruptIn for changing state on ECHO PIN [HIGH,LOW]
Powers 0:a3bc6812cccb 63 echo.rise(callback(this, &HCSR04::startTimer));
Powers 0:a3bc6812cccb 64 echo.fall(callback(this, &HCSR04::stopTimer));
Powers 0:a3bc6812cccb 65
Powers 0:a3bc6812cccb 66 // Default Values
Powers 0:a3bc6812cccb 67 trigger.write(0);
Powers 0:a3bc6812cccb 68 update = false;
Powers 0:a3bc6812cccb 69
Powers 0:a3bc6812cccb 70 }
Powers 0:a3bc6812cccb 71
Powers 1:6f9e41e319ad 72 // Function to return the distance in cm, should be called if "checkUpdate()" returns true
Powers 0:a3bc6812cccb 73 float getDistance(void);
Powers 0:a3bc6812cccb 74 // Check for an updatet status for the measurement
Powers 0:a3bc6812cccb 75 bool checkUpdate(void);
Powers 0:a3bc6812cccb 76 // Function to start sending HIGH in periodic intervalls to TRIGGER PIN via a TICKER Object
Powers 0:a3bc6812cccb 77 void startSensor(int freq);
Powers 0:a3bc6812cccb 78 // Function to stop sending HIGH to TRIGGER PIN
Powers 0:a3bc6812cccb 79 void stopSensor(void);
Powers 0:a3bc6812cccb 80
Powers 0:a3bc6812cccb 81
Powers 0:a3bc6812cccb 82 };
Powers 0:a3bc6812cccb 83
Powers 0:a3bc6812cccb 84 #endif