Dropping USB connection when relay off

Projects Programming
1

Hi folks I have made following code:

void loop() {
  Serial.println("Turn off per default relay");
  digitalWrite(RELAY_0, LOW);
  Plant_0();
}


//MAP
//Planta [0] Hylla höger hörn.
void Plant_0() {
  digitalWrite(RELAY_0, LOW);
  int SOIL_MOISTURE_0 = analogRead(sensor);  //Sets valA1 as whatever the sensor reads
  delay(5000);
  Serial.println("read sensor wait..");
  Serial.println(SOIL_MOISTURE_0);
  delay(10000);

if (SOIL_MOISTURE_0 > 500) {
    Serial.println("turn on pump");
    digitalWrite(RELAY_0, HIGH);  //sets the relay to cut the power to the track
    Serial.println("delay 3 sec");
    delay(3000);
  }else
    digitalWrite(RELAY_0, LOW);
}

1relay_bb
1relay_bb3933×2778 448 KB

Everytime the relay is turned off The USB connection is dropped why?

Help me out

Thank you

2

Is there a flyback diode on the relay coil?
Maybe an inductive high voltage spike when the field of the relay coil collapses is causing problems?

3

The USB connection is dropping because the Arduino is resetting.
You should not power a relay from the Arduino.

The LED in your circuit lacks a current-limiting resistor.

4

oh I see so I really need to have an external power source for the relay?

5

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