Example Code for Arduino-Ultrasonic and Servo Debugging

Hardware Preparation

• Ultrasonic sensor: 1pc (included in the kit)
• Servo motor: 1pc (included in the kit)
• Romeo BLE controller: 1pc (included in the kit)
• Wires: Included in the kit
• Upper plate and sensor plate: Included in the kit

Software Preparation

• Arduino IDE (download from click here)
• Metro library: Download from Metro library
• Servo library: Included with the Arduino IDE.

Wiring Diagram

Connect the ultrasonic sensor and servo to the Romeo BLE controller as shown:

Other Preparation Work

1. Install the upper plate and secure the ultrasonic sensor/servo as per STEP3: Install Upper Plate.
2. Download the Metro library and add it to the Arduino IDE (Sketch → Include Library → Add .ZIP Library).

Sample Code

#include <Servo.h>
#include <Metro.h>
Metro measureDistance = Metro(50);
Metro sweepServo = Metro(20);

unsigned long actualDistance = 0;

Servo myservo;  // create servo object to control a servo
int pos = 60;
int sweepFlag = 1;


int URPWM = 3; // PWM Output 0－25000US，Every 50US represent 1cm
int URTRIG= 10; // PWM trigger pin
uint8_t EnPwmCmd[4]={0x44,0x02,0xbb,0x01};    // distance measure command

void setup(){                                 // Serial initialization
  myservo.attach(9);
  Serial.begin(9600);                         // Sets the baud rate to 9600
  SensorSetup();
}

void loop(){
 if(measureDistance.check() == 1){
      actualDistance = MeasureDistance();
//      Serial.println(actualDistance);
//      delay(100);
 }

 if(sweepServo.check() == 1){
      servoSweep();
 }

}

void SensorSetup(){
  pinMode(URTRIG,OUTPUT);                     // A low pull on pin COMP/TRIG
  digitalWrite(URTRIG,HIGH);                  // Set to HIGH
  pinMode(URPWM, INPUT);                      // Sending Enable PWM mode command
  for(int i=0;i<4;i++){
      Serial.write(EnPwmCmd[i]);
   }
}

int MeasureDistance(){        // a low pull on pin COMP/TRIG  triggering a sensor reading
    digitalWrite(URTRIG, LOW);
    digitalWrite(URTRIG, HIGH);               // reading Pin PWM will output pulses
    unsigned long distance=pulseIn(URPWM,LOW);
    if(distance==50000){              // the reading is invalid.
      Serial.print("Invalid");
    }else{
      distance=distance/50;           // every 50us low level stands for 1cm
    }
    return distance;
}

void servoSweep(){
  if(sweepFlag ){
     if(pos>=60 && pos<=120){
        pos=pos+1;                                  // in steps of 1 degree
        myservo.write(pos);                         // tell servo to go to position in variable 'pos'
    }
      if(pos>119)  sweepFlag = false;                       // assign the variable again
  }else {
      if(pos>=60 && pos<=120){
        pos=pos-1;
        myservo.write(pos);
      }
      if(pos<61)  sweepFlag = true;
   }
}

Result

• The servo will sweep smoothly from 60° to 120° and back.
• The ultrasonic sensor will measure distance every 50ms. Invalid readings will print "Invalid" to the serial monitor; valid readings will print the distance in centimeters.

Additional Information

• If the servo position is misaligned:
  1. Reinstall the servo wheel to adjust the starting position.
  2. Modify the pos variable in the code to change the sweep range.