@apl2017 Verifying the reading is something you have to write into the sketch yourself, nothing complicated. I didn't use a library so no idea what advantage it brings over the simple timing method. Because I only take readings every hour triggered by an RTC, I don't care if it is the same as previous, only that it is valid in which case it is sent in.
Parts of my sketch follow, all fairly self-explanatory, perhaps they are of some use.
Main loop - Call subroutine and test to ensure it lies between two values, up to 10 attempts allowed to get a proper reading.
while ((tankdepth<350||tankdepth>1000)&&counter<=10){//10 attempts to get proper range
READULTRASONIC();
counter++;
}
The READULTRASONIC subroutine uses the simple timing method to get the 2 consecutive readings.
void READULTRASONIC(){//JSN-SR04-2.0
//Main loop checks valid range on a defined number of readings
tankdepth=0;
duration=0;
distance=0;
test=1;
test2=3;
// Normal range should lie between 389 and 989 absolutely empty is 1520
while (test!=test2){// Get two consecutive readings
digitalWrite(Trigpin, LOW);
delayMicroseconds(100);
digitalWrite(Trigpin, HIGH);
delayMicroseconds(150);
digitalWrite(Trigpin, LOW);
duration = pulseIn(Echopin, HIGH);
distance = duration/5.82;//This is in mm
if (test!=distance){
test=distance;
distance=0;
}
else{
test2=distance;
}
delay(100);///// 500 originally but why???????
}
tankdepth=distance;
}
There are many version of these sensors, neither of the two I trialled reliably ran unless on 5v, which made it bit more complicated for a 3.3v Node.
One operated on softserial from memory, but I couldn't get it to do what I wanted, I settled on the one which allows straightforward timing.
When I was first testing these, the first reading would always be a zero for reasons unknown, then solid readings, but the 2 consecutive readings test worked for me.
