DFRobot ultrasonic sensor SEN0313 UART

Support Arduino
1

Hi. first post so here goes.
I bought this DFrobot SEN0313 UART ultrasonic sensor to measure water levels. The demo program from the DFRobot site works but has a sampling frequency of approx 100ms. I want to stretch it out to approx 5 mins using a Arduino Uno. I then plan to upload the distance via Lora in JSON.

I need some help to mod this code below to read the sensor every 5 mins.
ANy help with it would be greatly appreciated.

#include <SoftwareSerial.h>

SoftwareSerial mySerial(11,10); // 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>280)
          {
           Serial.print("distance=");
           Serial.print(distance/10);
           Serial.println("cm");
          }else 
              {
                Serial.println("Below the lower limit");        
              }
      }else Serial.println("ERROR");
     }
     delay(150);
}
2 Likes
2

Hi Mal,

It’s been a while since I’ve done anything in Arduino (Micropython spoils you :smiley: ).
It’s a very quick any dirty implementation, to get more accurate timings and if you want to make use of any low power modes I’d consider using an RTC and an interrupt on the Arduino!

#include <SoftwareSerial.h>

SoftwareSerial mySerial(11,10); // RX, TX
unsigned char data[4]={};
float distance;
uint16_t counter = 0; // Create a counter

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(counter >= 600){ // Counts up to 500 seconds
    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>280)
            {
             Serial.print("distance=");
             Serial.print(distance/10);
             Serial.println("cm");
            }else 
                {
                  Serial.println("Below the lower limit");        
                }
        }else Serial.println("ERROR");
       }
       counter = 0
  }
     delay(1000); // Delays the loop by 1 second
     counter = counter + 1 //Iterates the counter
}

PS: if you put ``` ``` around your code you can make it look like the language it was written in.

Let me know how the sketch goes!
Liam

1 Like
3

Thanks for your feedback and tip about the "’ "’ Liam.
I gave it a try but now im just getting ERROR in the serial monitor.
I think there is something inherent in the UART operation of this sensor. Its specs state is should responds in 100-150ms. I suspect the instruction to fill the array in the code is not timed correctly when a delay is used.

I tried the code in a sub-routine program instruction which was called once every minute and it looked like it never got any data from the sensor.

Im at a bit of a loss which is a shame, it seems to be a good, accurate and repeatable sensor suited for outdoor IOT projects like water level sensing.

cheers
mal

3 Likes
4

Hi Mal,

If you change count to 6000 and the delay to 100 it should work, the serial buffer might not roll over and just fill up then the Arduino doesn’t know what to do.There’s definitely a way to do what you’re after :smiley:

2 Likes
5

Hi Mal,

Ahh, I had missed the part in the product Wiki where it mentions that a stream is sent back, the code below should work:

#include <SoftwareSerial.h>

SoftwareSerial mySerial(11,10); // RX, TX
unsigned char data[4]={};
float distance;
uint16_t counter = 0; // Create a counter

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(counter >= 2000){ // Counts up to 500 seconds
    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>280)
            {
             Serial.print("distance=");
             Serial.print(distance/10);
             Serial.println("cm");
            }else 
                {
                  Serial.println("Below the lower limit");        
                }
        }else Serial.println("ERROR");
       }
       counter = 0
  }
     delay(150); // Delays the loop by 150 milliseconds
     counter = counter + 1 //Iterates the counter
}

The counter condition is calculated using the formula

3 000 000 = delay*counter

Where you can select the delay to suit when the serial data enters the buffer.

Liam

1 Like