My serial monitor is printing garbage

[braingix]

Hello, this Is my first time posting here.
I am working on a project(bluetooth controlled car). I am using the adafruit motor shield V1. After connecting everything to arduino and uploading my code>>
`
/******************* Robot Remote Control Mode ********************/

// include the Adafruit motor v1 library
#include <AFMotor.h>

AF_DCMotor MotorFR(1); // Motor for drive Front Right on M1
AF_DCMotor MotorFL(2); // Motor for drive Front Left on M2
AF_DCMotor MotorBL(3); // Motor for drive Back Left on M3
AF_DCMotor MotorBR(4); // Motor for drive Back Right on M4

const int buzPin = 2; // set digital pin 2 as buzzer pin (use active buzzer)
const int ledPin = A5; // set digital pin A5 as LED pin (use super bright LED)
int valSpeed = 255;

void setup(){
Serial.begin(9600); // set up Serial library at 9600 bps
Serial.println("Robot Remote Control Mode");
Serial.println("READY TO GO");

pinMode(buzPin, OUTPUT); // sets the buzzer pin as an Output
pinMode(ledPin, OUTPUT); // sets the LED pin as an Output

// Set the speed to start, from 0 (off) to 255 (max speed)
MotorFL.setSpeed(valSpeed);
MotorFR.setSpeed(valSpeed);
MotorBL.setSpeed(valSpeed);
MotorBR.setSpeed(valSpeed);
// turn off motor
MotorFL.run(RELEASE);
MotorFR.run(RELEASE);
MotorBL.run(RELEASE);
MotorBR.run(RELEASE);
}

void loop() {
while (Serial.available() > 0) {
char command = Serial.read(); // gets one byte from serial buffer
Serial.println(command);

switch(command){
case 'F':   // move forward
    SetSpeed(valSpeed);
    MotorFL.run(FORWARD);
    MotorFR.run(FORWARD);
    MotorBL.run(FORWARD);
    MotorBR.run(FORWARD);
    break;
case 'B':   // move backward
    SetSpeed(valSpeed);
    MotorFL.run(BACKWARD);
    MotorFR.run(BACKWARD);
    MotorBL.run(BACKWARD);
    MotorBR.run(BACKWARD);
    break;
case 'R':   // turn right
    SetSpeed(valSpeed);
    MotorFL.run(FORWARD);
    MotorFR.run(BACKWARD);
    MotorBL.run(FORWARD);
    MotorBR.run(BACKWARD);
    break;
case 'L':   // turn left
    SetSpeed(valSpeed);
    MotorFL.run(BACKWARD);
    MotorFR.run(FORWARD);
    MotorBL.run(BACKWARD);
    MotorBR.run(FORWARD);
    break;
case 'G':   // forward left
    MotorFL.setSpeed(valSpeed/4);
    MotorBL.setSpeed(valSpeed/4);
    MotorFL.run(FORWARD);
    MotorFR.run(FORWARD);
    MotorBL.run(FORWARD);
    MotorBR.run(FORWARD);
    break;
case 'H':   // backward left
    MotorFL.setSpeed(valSpeed/4);
    MotorBL.setSpeed(valSpeed/4);
    MotorFL.run(BACKWARD);
    MotorFR.run(BACKWARD);
    MotorBL.run(BACKWARD);
    MotorBR.run(BACKWARD);
    break;
case 'I':   // forward right
    MotorFR.setSpeed(valSpeed/4);
    MotorBR.setSpeed(valSpeed/4);
    MotorFL.run(FORWARD);
    MotorFR.run(FORWARD);
    MotorBL.run(FORWARD);
    MotorBR.run(FORWARD);
    break;
case 'J':   // backward right
    MotorFR.setSpeed(valSpeed/4);
    MotorBR.setSpeed(valSpeed/4);
    MotorFL.run(BACKWARD);
    MotorFR.run(BACKWARD);
    MotorBL.run(BACKWARD);
    MotorBR.run(BACKWARD);
    break;
case 'S':   // stop
    MotorFL.run(RELEASE);
    MotorFR.run(RELEASE);
    MotorBL.run(RELEASE);
    MotorBR.run(RELEASE);
    break;
case 'V':   // beep buzzer
    digitalWrite(buzPin, HIGH);
    delay(150);        
    digitalWrite(buzPin, LOW);
    delay(100);        
    digitalWrite(buzPin, HIGH);
    delay(250);        
    digitalWrite(buzPin, LOW);
    break;
case 'W':   // turn light on
    digitalWrite(ledPin, HIGH);
    break;
case 'w':   // turn light off
    digitalWrite(ledPin, LOW);
    break;
case '0':   // set speed motor to 0 (min)
    SetSpeed(0);
    break;
case '1':   // set speed motor to 30
    SetSpeed(30);
    break;
case '2':   // set speed motor to 55
    SetSpeed(55);
    break;
case '3':   // set speed motor to 80
    SetSpeed(80);
    break;
case '4':   // set speed motor to 105
    SetSpeed(105);
    break;
case '5':   // set speed motor to 130
    SetSpeed(130);
    break;
case '6':   // set speed motor to 155
    SetSpeed(155);
    break;
case '7':   // set speed motor to 180
    SetSpeed(180);
    break;
case '8':   // set speed motor to 205
    SetSpeed(205);
    break;
case '9':   // set speed motor to 230
    SetSpeed(230);
    break;
case 'q':   // set speed motor to 255 (max)
    SetSpeed(255);
    break;
} 

}
}

// function for setting speed of motors
void SetSpeed(int val){
valSpeed = val;
MotorFL.setSpeed(val);
MotorFR.setSpeed(val);
MotorBL.setSpeed(val);
MotorBR.setSpeed(val);
}
`
I then open the serial monitor only to see a totally different thing from what I was expecting. Please I need help to understand what's wrong.

[UKHeliBob]

Welcome to the forum

@braingix

my code

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Assuming that you have the Serial monitor baud rate set to match the sketch, are you seeing numbers instead of letters by any chance ?

Maybe 66 when you expect B, for example ?

[red_car]

@braingix

only to see a totally different thing from what I was expecting

Be kinda useful if you were able to share what:

a). you were expecting to see.
b). you actually see.

[braingix]

[red_car]

Try just cut & paste... pic is pretty hard to see anything useful.

[hammy]

Check your serial monitor is set to 9600 ( bottom right hand corner )

[braingix]

On the serial monitor>>

Rnbnt Rdlntd Bnntrnl Lndd(instead of Remote control mode)

RD@DX TN FN(instead of READY TO GO)

[red_car]

Baud rate in monitor ? 9600?

[braingix]

Yes, 9600 baud

[braingix]

Yes

[red_car]

So what does this produce?

void setup()
{
  Serial.begin(9600);
  Serial.println("Hello World!");
}


void loop()
{
  
}

[hammy]

Disconnect everything, run the example hello world sketch and see what you get , then run your code , then starting connecting stuff and see how things change - this will help identify issues .
I take it you have nothing connected to pins 0,1 which are used by USB.

[braingix]

After uploading the Hello world it prints Hello world.

[braingix]

I haven't connect the bluetooth module yet. When I connected the bluetooth module at first, the data from the bluetooth module was printing as garbage too so I had to disconnect it and to check if the issue was with the module but it wasn't.

[pmagowan]

Show your wiring.

[pmagowan]

Forget that, your buzzer is on pin 2? Is this in conflict with serial on your arduino?

[octopirate]

@braingix

After uploading the Hello world it prints Hello world.

With or without the shield plugged in?

[aamiragwani]

your circuit must have common GND, please check that first.

[braingix]

With the shield plugged in.

[braingix]

My wiring is correct sir, I attached the shield to the board. I don't think there is any wrong connection there.

My wiring is same as here unless for the servo and IR sensors.