การแก้ปัญหา error: multiple definition of `Serial2'

Remy_Martin · 2020-02-20T09:23:44Z

Code

HardwareSerial Serial2(2);             //Needed since this is an ESP32

void setup() {
  Serial.begin(115200);
  Serial2.begin(115200, SERIAL_8N1, 16, 17);
}

void loop() {  
  if (Serial.available())           // If user typed something through the USB...
  {      
    Serial2.write(Serial.read());   // Push it through Port 2 to Central ESP32
  }
  if (Serial2.available())          // If data is received through Port 2 from Central ESP32
  {     
    Serial.write(Serial2.read()); // Show data on Serial Monitor 2 
  }
}

error code

Arduino: 1.8.8 (Windows 10), Board: "DOIT ESP32 DEVKIT V1, 80MHz, 115200, None"

core\core.a(HardwareSerial.cpp.o):(.bss.Serial2+0x0): multiple definition of `Serial2'

sketch\1x1_Beta_SoilWatch10_Send.ino.cpp.o:(.bss.Serial2+0x0): first defined here

collect2.exe: error: ld returned 1 exit status

exit status 1
Error compiling for board DOIT ESP32 DEVKIT V1.

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วิธีแก้ไข
เนื่องจากมีการประกาศ Serial ซ้ำกันจึงต้องลบบรรทัดที่ซ้ำออก

#include <HardwareSerial.h>
//HardwareSerial Serial2(2);             //Needed since this is an ESP32

void setup() {
  Serial.begin(115200);
  Serial2.begin(115200, SERIAL_8N1, 16, 17);
}

void loop() {  
  if (Serial.available())           // If user typed something through the USB...
  {      
    Serial2.write(Serial.read());   // Push it through Port 2 to Central ESP32
  }
  if (Serial2.available())          // If data is received through Port 2 from Central ESP32
  {     
    Serial.write(Serial2.read()); // Show data on Serial Monitor 2 
  }
}