问如果连接到SoftwareSerial，则无法打印到串行

EN

#include <SoftwareSerial.h>

SoftwareSerial BTserial(1, 3); // RX | TX

String reading;

void setup() 
{
    // Arduino IDE serial monitor
    Serial.begin(9600);

    Serial.println("hoihoi");
    // HC-05 default serial speed for AT mode is 38400
    BTserial.begin(9600);  

    // Wait for hardware to initialize
    delay(1000);

    // Print debug string
}

void loop()
{
  Serial.println("hoi");
   // Keep reading from HC-05 and send to Arduino Serial Monitor
   if (BTserial.available())
   {
      String reading = (String)BTserial.read();
      Serial.println(reading);

      //input from mobile is 1 AKA 10% PWM
      if(reading == "1"){
        Serial.println("Input from Bluetooth is 1");
      } 

      //input from mobile is 2 AKA 100% PWM
      else if(reading == "2") {
        Serial.println("Input from Bluetooth is 2");        
      }

      //input from mobile is 3 AKA 0% PWM
      else if(reading == "3") {
        Serial.println("Input from Bluetooth is 3");        
      }  
   }
}