Hi everybody,
I am completely new in this Arduino environment and I have a project that I’m gonna use waterproof ultrasonic sensor A02YYUW.
I am using Arduino Nano. When I upload the code below, I am getting the same values. Even the location of the sensoris constant, the values are same and I am getting the value of 0 cm mostly. I dont know how it is possible.
I did the same connections as sample project.
Could you please check and give me some support on my project?
Thanks in advance!
Can I know some details of your project. Is it the waterproof sensor and you are measuring the values in the water right ?
I am building a robotic fish. Yes it is a waterproof sensor. It is strange but I got the same values even if i put the sensor in the water.
That code appears to be for a standard ultrasonic distance sensor.
The sensor you have has a special serial interface. Here is a description which includes a code sample: A02YYUW Waterproof Ultrasonic Sensor Wiki - DFRobot
Hi 6v6gt,
I have tried that sample code as well. But the sensor gives strange values. You may see below. I do not understand what is wrong. 
Change the baud rate on your serial console from 9600 to this 57600 . If that fails, post the code you used for that test.
I got this ERROR message when I changed the baud rate.
Here is the code that I am using:
/*
*@File : DFRobot_Distance_A02.ino
*@Brief : This example use A02YYUW ultrasonic sensor to measure distance
* With initialization completed, We can get distance value
*@Copyright [DFRobot](http://www.dfrobot.com),2016
* GUN Lesser General Pulic License
*@version V1.0
*@data 2019-8-28
*/
#include <SoftwareSerial.h>
SoftwareSerial mySerial(A0,A2); // RX, TX
unsigned char data[4]={};
float distance;
void setup()
{
Serial.begin(57600);
mySerial.begin(9600);
}
void loop()
{
do{
for(int i=0;i<4;i++)
{
data[i]=mySerial.read();
}
}while(mySerial.read()==0xff);
mySerial.flush();
if(data[0]==0xff)
{
int sum;
sum=(data[0]+data[1]+data[2])&0x00FF;
if(sum==data[3])
{
distance=(data[1]<<8)+data[2];
if(distance>30)
{
Serial.print("distance=");
Serial.print(distance/10);
Serial.println("cm");
}else
{
Serial.println("Below the lower limit");
}
}else Serial.println("ERROR");
}
delay(100);
}
Try changing this line:
else Serial.println("ERROR");
To:
else {
Serial.println("ERROR");
Serial.print( data[0] ,HEX ); Serial.print( data[1] ,HEX ); Serial.print( data[2] ,HEX ); Serial.println( data[3] ,HEX ) ;
}
And post the output.
Yes, the results don't look very good.
I can't see what colour wires go into the sensor, but these must match your pin definitions iny our code here:
The Green wire appears to be RX from the illustration in the documentation, but it is not clear if that is a standard. It appears to be different to your wiring. Anyway, just check it again.
You are right, my wiring was not correct 
Anyway, I am getting these values right now. It does not seem stable. Is it normal or is there still a problem?
A couple of random thoughts after looking around for more details on this sensor ...
From the previous link to the product: "When "RX" floats or input High level, the module outputs processed value, the data is more steady, response time: 100-300ms; when input Low level, the module outputs real-time value, response time: 100ms."
When you get valid readings from the sensor, do they tie in with the distance to the object in front of the sensor?
The "waterproof" ultrasonic sensor A02YYUW is really just rainproof, and will work only in air.
For underwater distance measurements, very different transducers and circuitry are required (fish finders, for example).
