ElderPlus_SecuritySystem - 2nd year embedded systems project

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2nd year embedded systems project

Door_1_Docs/hcsr04.cpp@1:9d7c34bfe43e, 2020-12-15 (annotated)

Simple Electronic Lock (Solenoid) code

User	Revision	Line number	New contents of line
nwabiam	1:9d7c34bfe43e	1	#include "hcsr04.h"
nwabiam	1:9d7c34bfe43e	2	#include "mbed.h"
nwabiam	1:9d7c34bfe43e	3	/*
nwabiam	1:9d7c34bfe43e	4	*HCSR04.cpp
nwabiam	1:9d7c34bfe43e	5	*/
nwabiam	1:9d7c34bfe43e	6	HCSR04::HCSR04(PinName t, PinName e) : trig(t), echo(e) {}
nwabiam	1:9d7c34bfe43e	7	float HCSR04::echo_duration() {
nwabiam	1:9d7c34bfe43e	8
nwabiam	1:9d7c34bfe43e	9	timer.reset(); //reset timer
nwabiam	1:9d7c34bfe43e	10	trig=0; // trigger low
nwabiam	1:9d7c34bfe43e	11	wait_us(2); // wait
nwabiam	1:9d7c34bfe43e	12	trig=1; // trigger high
nwabiam	1:9d7c34bfe43e	13	wait_us(10);
nwabiam	1:9d7c34bfe43e	14	trig=0; // trigger low
nwabiam	1:9d7c34bfe43e	15	while(!echo); // start pulseIN
nwabiam	1:9d7c34bfe43e	16	timer.start();
nwabiam	1:9d7c34bfe43e	17	while(echo);
nwabiam	1:9d7c34bfe43e	18	timer.stop();
nwabiam	1:9d7c34bfe43e	19	return timer.read_us();
nwabiam	1:9d7c34bfe43e	20
nwabiam	1:9d7c34bfe43e	21	}
nwabiam	1:9d7c34bfe43e	22
nwabiam	1:9d7c34bfe43e	23	//return distance in cm
nwabiam	1:9d7c34bfe43e	24	float HCSR04::distance(){
nwabiam	1:9d7c34bfe43e	25	duration = echo_duration();
nwabiam	1:9d7c34bfe43e	26	distance_cm = (duration/2)/29.1 ;
nwabiam	1:9d7c34bfe43e	27	return distance_cm;
nwabiam	1:9d7c34bfe43e	28
nwabiam	1:9d7c34bfe43e	29	}