void setup() {
  Serial.begin(115200); // Serial Monitor for debugging
  Serial1.begin(115200); // Start at default RYLR998 baud rate
  delay(1000); // Wait for RYLR998 to stabilize

  Serial.println("Starting RYLR998 baud rate reprogramming...");

  // Test communication at 115200 baud
  sendATCommand("AT", "+OK", 115200); // Verify module responsiveness
  sendATCommand("AT+RESET", "+RESET", 115200); // Reset module
  sendATCommand("AT+IPR=9600", "+OK", 115200); // Set baud rate to 9600

  // Switch to 9600 baud
  Serial1.end(); // Close Serial1 at 115200
  delay(500);
  Serial1.begin(9600); // Reopen at 9600
  delay(1000); // Wait for stabilization

  // Verify communication at 9600 baud
  sendATCommand("AT", "+OK", 9600); // Test at new baud rate
  sendATCommand("AT+UART?", "+UART", 9600); // Confirm baud rate
  Serial.println("RYLR998 reprogrammed to 9600 baud. Configuration complete.");
}

void loop() {
  // No loop actions needed; script runs once
}

// Helper function to send AT command and print response
void sendATCommand(String command, String expected, int baudRate) {
  Serial1.println(command);
  Serial.print("Sent AT (");
  Serial.print(baudRate);
  Serial.print(" baud): ");
  Serial.println(command);
  String response = waitForResponse(2000);
  Serial.print("Response: ");
  Serial.println(response);
  if (!response.startsWith(expected)) {
    Serial.println("Warning: Unexpected response for " + command);
  }
}

// Helper function to read response from RYLR998
String waitForResponse(unsigned long timeout) {
  unsigned long start = millis();
  String response = "";
  while (millis() - start < timeout) {
    if (Serial1.available()) {
      response += Serial1.readStringUntil('\n');
      if (response.length() > 0) return response; // Return on first complete response
    }
    delay(10); // Small delay to prevent tight loop
  }
  return response; // Return empty or partial response if timeout
}