Can't solve the bug about Robot movement!

I'm working on a mobile robot that is controled with bts7960B motor driver for 2 whells. I'm using raspberry pi 5 for triggering arduino uno and control. Arduino is controlling the motor drivers. There is a bug about the movement, during the driving when it receives the consol input from my ps4 controller While driving the robot normally with my PS4 controller, for some reason I don't understand, it stays on the last command I sent and the vehicle gets stuck on the last movement it made, for example, I press forward and it continues to go forward even though I don't press it. I cannot return the robot to its previous state without pressing the reset button on the Arduino. Here is my arduino code:

#define L_EN1 2
#define R_EN1 4
#define L_PWM1 5
#define R_PWM1 6

#define L_EN2 8
#define R_EN2 10
#define L_PWM2 11
#define R_PWM2 9

void setup()
{
Serial.begin(115200);

pinMode(L_EN1, OUTPUT);
pinMode(R_EN1, OUTPUT);
pinMode(L_PWM1, OUTPUT);
pinMode(R_PWM1, OUTPUT);

pinMode(L_EN2, OUTPUT);
pinMode(R_EN2, OUTPUT);
pinMode(L_PWM2, OUTPUT);
pinMode(R_PWM2, OUTPUT);

digitalWrite(L_EN1, LOW);
digitalWrite(R_EN1, LOW);
digitalWrite(L_EN2, LOW);
digitalWrite(R_EN2, LOW);

pinMode(LED_BUILTIN, OUTPUT);
}

void motor1Forward(int speed)
{
digitalWrite(L_EN1, HIGH);
digitalWrite(R_EN1, HIGH);
analogWrite(R_PWM1, 0);
analogWrite(L_PWM1, speed);
}

void motor1Reverse(int speed)
{
digitalWrite(L_EN1, HIGH);
digitalWrite(R_EN1, HIGH);
analogWrite(R_PWM1, speed);
analogWrite(L_PWM1, 0);
}

void motor2Forward(int speed)
{
digitalWrite(L_EN2, HIGH);
digitalWrite(R_EN2, HIGH);
analogWrite(R_PWM2, 0);
analogWrite(L_PWM2, speed);
}

void motor2Reverse(int speed)
{
digitalWrite(L_EN2, HIGH);
digitalWrite(R_EN2, HIGH);
analogWrite(R_PWM2, speed);
analogWrite(L_PWM2, 0);
}

void stopMotors()
{
digitalWrite(R_EN1, LOW);
digitalWrite(L_EN1, LOW);
digitalWrite(L_EN2, LOW);
digitalWrite(R_EN2, LOW);
analogWrite(R_PWM1, 0);
analogWrite(L_PWM1, 0);
analogWrite(R_PWM2, 0);
analogWrite(L_PWM2, 0);
}

int led_opened = 0;

void loop() {
if (Serial.available() > 0)
{
char command = Serial.read();

if (command == 'w') {
motor1Forward(255);
motor2Forward(255);

}
else if (command == 's') {
motor1Reverse(255);
motor2Reverse(255);

}
else if (command == 'a') {
motor1Reverse(255);
motor2Forward(255);
}
else if (command == 'd') {
motor1Forward(255);
motor2Reverse(255);
}
else if (command == 'r') {
stopMotors();
}
/*else if (command == 'y') {
stopMotors();

digitalWrite(LED_BUILTIN, HIGH);
}
else if (command == 'n') {
stopMotors();

digitalWrite(LED_BUILTIN, LOW);
}
*/

Serial.flush();

}
}

Thank you in advance for your help!

I am working with Arduino and i am having problem when communicating from Raspberry PI to Arduino. I have two motor drivers `(bts7960B)` that connected to the Arduino. And with Serial i am trying to control arduino (like start motor, reverse motor) with Raspberry PI. I connected my wireless controller and i am sending command to arduino with Python. My code sending `"w"` for forward and `"r"` to reverse and when joystick button relased i am sending `"r"` for stop my motors. For sending command i am using pyserial. And inside of Arduino gets commands with `Serial.read()` and applying commands and settings motors pwms. But sometimes I think there is an error in my Arduino and it stays on the last command sent to the Arduino. When the problem occurs, if `"w"` is sent last, my Arduino acts as if this command is being sent all the time. And that's why the motors are constantly running. And when I look at the `tx` led on my Arduino, nothing happens. So I couldn't understand what exactly happened to my Arduino here. Can you help me with this?

Here is my Python control code:

``` lang-python

import serial

import pygame

import time

import threading

# Arduino setup

arduino = serial.Serial('/dev/arduino1', 115200)

# Initialize Pygame

pygame.init()

pygame.joystick.init()

# Check if joystick is connected

if pygame.joystick.get_count() == 0:

print("No joystick connected")

else:

# Initialize joystick

joystick = pygame.joystick.Joystick(0)

joystick.init()

def arduino_movement():

while True:

for event in pygame.event.get():

if event.type == pygame.JOYHATMOTION:

if event.value == (0, 1):

arduino.write(b'w')

elif event.value == (0, -1):

arduino.write(b's')

elif event.value == (1, 0):

arduino.write(b'd')

elif event.value == (-1, 0):

arduino.write(b'a')

elif event.value == (0, 0):

arduino.write(b'r')

print(event)

time.sleep(0.1) # Small delay to make output readable

# Start threads

try:

arduino_thread = threading.Thread(target=arduino_movement, daemon=True)

arduino_thread.start()

# Keep the main program running

while True:

time.sleep(1)

except KeyboardInterrupt:

print("Program interrupted")

finally:

pygame.joystick.quit()

pygame.quit()

print("Pygame and joystick resources released")

```

And here is the Arduino code:

``` lang-cpp

#define L_EN1 2

#define R_EN1 4

#define L_PWM1 5

#define R_PWM1 6

#define L_EN2 8

#define R_EN2 10

#define L_PWM2 11

#define R_PWM2 9

void setup()

{

Serial.begin(115200);

pinMode(L_EN1, OUTPUT);

pinMode(R_EN1, OUTPUT);

pinMode(L_PWM1, OUTPUT);

pinMode(R_PWM1, OUTPUT);

pinMode(L_EN2, OUTPUT);

pinMode(R_EN2, OUTPUT);

pinMode(L_PWM2, OUTPUT);

pinMode(R_PWM2, OUTPUT);

digitalWrite(L_EN1, LOW);

digitalWrite(R_EN1, LOW);

digitalWrite(L_EN2, LOW);

digitalWrite(R_EN2, LOW);

}

void motor1Forward(int speed)

{

digitalWrite(L_EN1, HIGH);

digitalWrite(R_EN1, HIGH);

analogWrite(R_PWM1, 0);

analogWrite(L_PWM1, speed);

}

void motor1Reverse(int speed)

{

digitalWrite(L_EN1, HIGH);

digitalWrite(R_EN1, HIGH);

analogWrite(R_PWM1, speed);

analogWrite(L_PWM1, 0);

}

void motor2Forward(int speed)

{

digitalWrite(L_EN2, HIGH);

digitalWrite(R_EN2, HIGH);

analogWrite(R_PWM2, 0);

analogWrite(L_PWM2, speed);

}

void motor2Reverse(int speed)

{

digitalWrite(L_EN2, HIGH);

digitalWrite(R_EN2, HIGH);

analogWrite(R_PWM2, speed);

analogWrite(L_PWM2, 0);

}

void stopMotors()

{

digitalWrite(R_EN1, LOW);

digitalWrite(L_EN1, LOW);

digitalWrite(L_EN2, LOW);

digitalWrite(R_EN2, LOW);

analogWrite(R_PWM1, 0);

analogWrite(L_PWM1, 0);

analogWrite(R_PWM2, 0);

analogWrite(L_PWM2, 0);

}

void loop() {

if (Serial.available() > 0)

{

char command = Serial.read();

if (command == 'w') {

motor1Forward(255);

motor2Forward(255);

}

else if (command == 's') {

motor1Reverse(255);

motor2Reverse(255);

}

else if (command == 'a') {

motor1Reverse(255);

motor2Forward(255);

}

else if (command == 'd') {

motor1Forward(255);

motor2Reverse(255);

}

else if (command == 'r') {

stopMotors();

}

Serial.flush();

}

}

```