Example Code for Arduino-Switch Output

Hardware Preparation

• DFRduino UNO R3 (or similar) x 1
• Water-proof Ultrasonic Sensor (ULS) x1
• Connectors

Software Preparation

• Arduino IDE

Wiring Diagram

Other Preparation Work

The internal probe surface is regarded as the detecting starting point by default. If you take the plane of the bell-mouth as starting point, then the distance will be the detected distance minus 40mm.

Sample Code

* **************************************************** 
* @brief Water-proof Ultrasonic Sensor (ULS)

 * @copyright	[DFRobot](https://www.dfrobot.com), 2016
 * @copyright	GNU Lesser General Public License

* @author [Xiaoyu]([email protected])
* @version  V1.0
* @date  2019-03-11
  
* GNU Lesser General Public License.
* All above must be included in any redistribution
* ****************************************************/
#include <SoftwareSerial.h>
SoftwareSerial mySerial(10, 11); // RX, TX
unsigned char buffer_RTT[7] = {};
unsigned long duration;
int datapin = 9;
void setup() {
        Serial.begin(57600);     // Enable serial port and set band rate to 57600 bps
        mySerial.begin(9600);
        pinMode(LED_BUILTIN, OUTPUT);
        pinMode(datapin, INPUT);
        digitalWrite(LED_BUILTIN, HIGH);
}

void loop() {
        digitalWrite(LED_BUILTIN, LOW);//give low level
        duration = digitalRead(datapin);//read pin state 
        delay(3);
        switch(duration){
        case 0 :Serial.println("LOW"); break;//the distance to the object is less than the preset distance, set the defalut to 1m
        case 1 :Serial.println("HIGH"); break;//the distance to the object is more than the preset distance    
        }          
        }  

Result