Servo retaining its position every time I send some value

Question

I wanted to control my servo with a Bluetooth module.

I gave certain values for rotating it. When I press those values the servo rotates, but then retains its original position and the PC also makes the sound of the Arduino board disconnecting because I powered the board with my PC (tried with powerbank also). Even my Bluetooth disconnects.

This is my code:

#include <Servo.h>

Servo myservo;
int pos = 0;
char data = 0; 
           
void setup() {
  myservo.attach(9);
  Serial.begin(9600);
}

void loop() {
  if (Serial.available() > 0) { 
    data = Serial.read();             
    if (data == 'F') {        
      // for (pos = 0; pos <= 180; pos += 1) 
      myservo.write(180);
      delay(1);
    }
  }
  else if (data == 'B') {     
    // for (pos = 180; pos >= 0; pos -= 1) 
    myservo.write(0); 
    delay(1);
  }
}

Connections:

Servo:

red wire -- 5 V (not working at 3.3 V)
orange wire -- pin9
brown wire -- gnd

Bluetooth (hc05):

5 V -- 5 V
gnd -- gnd
rx -- tx
tx -- rx

Answer 1

I tried changing the USB B cable with a better quality one and it worked.