Example Code for Arduino-UART Mode

Hardware Preparation

• SRF02 Ultrasonic Sensor, SKU:SEN0005, Quantity:1, Purchase Link
• Arduino Leonardo (or Arduino UNO), Quantity:1

Software Preparation

• Development Tool: Arduino IDE (version 1.8.x or later). Download link
• Library: SoftwareSerial library (included with Arduino IDE for Arduino UNO; no additional installation needed for Leonardo)

Wiring Diagram

For Arduino Leonardo:

For Arduino UNO (Software Serial):

Change "Serial1" to "mySerial" and add #include <SoftwareSerial.h> and SoftwareSerial mySerial(10, 11); // RX, TX to the code. Connect SRF02's Rx to Arduino UNO's TX (pin 11) and Tx to Arduino UNO's RX (pin 10).

Other Preparation Work

For UART mode, connect the "Mode" pin of the SRF02 to GND. For Arduino UNO, use Software Serial and adjust the pin connections accordingly.

Sample Code

    /*
    Sample code for test the SRF02 with the UART mode based on Leonardo!
    Command for reference:http://robot-electronics.co.uk/htm/srf02techSer.htm
    Connection:
    SRF02       Arduino
    5v Vcc    -> 5V
    Rx        -> 1(TX)
    Tx        -> 0(RX)
    Mode      -> GND
    0v Ground -> GND
    */

    void SendCmd(unsigned char address,unsigned char cmd)
    {
      Serial1.write(address);//set the address of SRF02(factory default is 0)
      delayMicroseconds(100);//serial data is fixed at 9600,N,8,2,so we need some time to creat the sencond stop bit
      Serial1.write(cmd);//send the command to SRF02
      delayMicroseconds(100);//serial data is fixed at 9600,N,8,2,so we need some time to creat the sencond stop bit
    }
    void setup(void)
    {
      Serial.begin(9600);
      Serial1.begin(9600);
      Serial.println("SRF02 TEST!");
    }
    void loop(void)
    {
      unsigned int reading;
      SendCmd(0x00,0x51);//Real Ranging Mode - Result in centimeters
      delay(70);//time for SRF02 to measure the range
      SendCmd(0x00,0x5E);//Get Range, returns two bytes (high byte first) from the most recent ranging.
      delay(10);//wait for some time,let the Arduino receive 2 bytes data from the TX pin of SRF02
      if(Serial1.available()>=2)//if two bytes were received
      {
        reading = Serial1.read()<<8;//receive high byte (overwrites previous reading) and shift high byte to be high 8 bits
        reading |= Serial1.read(); // receive low byte as lower 8 bits
        Serial.print(reading); // print the reading
        Serial.println("cm");
      }
      delay(250); // wait a bit since people have to read the output :)
    }

    #include <SoftwareSerial.h>  

    SoftwareSerial mySerial(10, 11); // RX, TX

Result

Open the Serial Monitor in Arduino IDE with baud rate 9600. You should see the distance measured by the SRF02 in centimeters printed continuously.

Additional Information

Command reference link: http://robot-electronics.co.uk/htm/srf02techSer.htm