40 lines
1.1 KiB
C++
40 lines
1.1 KiB
C++
#define US_TRIG 13
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#define US_ECHO 12
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long distance_cm, echo_duration;
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void setup() {
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//Serial port
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Serial.begin(115200);
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//Ultra sonic pins
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pinMode(US_TRIG, OUTPUT);
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pinMode(US_ECHO, INPUT);
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}
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void loop() {
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// start measurment by a short high pulse of 10 microseconds length at the trig pin ...
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digitalWrite(US_TRIG,LOW);
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delayMicroseconds(2);
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digitalWrite(US_TRIG,HIGH);
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delayMicroseconds(10);
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digitalWrite(US_TRIG,LOW);
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// measure the duration in microseconds of the echo pin HIGH - this is the time the echo needs to be back at the sensor
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pinMode(US_ECHO,INPUT);
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echo_duration = pulseIn(US_ECHO,HIGH);
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// convert into cm ... 344m/sec is the speed of noise - thus 34400cm/sec ... or 34,400cm/milisec ... or 0,0344cm/microsec
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// the echo has to go the distance twice - forth and back - so the duration has to be the half of the measured one
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// distance_cm = echo_duration/2 * 0,0344 or distance_cm = echo_duration/2 / 29,1
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distance_cm = (echo_duration/2) / 29.1;
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//print this result at the screen
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Serial.print("Distance in cm: ");
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Serial.println(distance_cm);
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//wait before next measurement
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delay(250); //ms
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}
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