Have problems with Multi serial in Arduino Mega and LCD 16x2

Projects Programming
1

Hey guys, im here again, i have a problem with multiserial and LCD16x2, maybe is that im not used to Arduino mega and it multiserial ports or functions. When i use the normal serial (serial.begin), my lcd show me the value of the MG811 sensor, but when i use the Serial2.begin and the condition of that serial, my LCD don't show me anything. Don't know what is the problem, here is my code:

#include "CO2Sensor.h"
#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,20,4);  // set the LCD address to 0x27 for a 16 chars and 2 line display

CO2Sensor co2Sensor(A0, 0.99, 100);

String val_CO2;

void setup() {
  
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.setCursor(0, 1);
  lcd.print("CO2:");
  //lcd.setCursor(7, 1);
  //lcd.print("CO:"); 

  Serial2.begin(9600);
  co2Sensor.calibrate();
}

void loop() {
  if (Serial2.available()){
  int val = co2Sensor.read();
  lcd.setCursor(4, 1);
  lcd.print(val);
  delay(1000);
  }
  //CO2 sensor

}

If you change the Serial2.begin to serial.begin, and erase the condition of Serial2.available, it works fine. Hope somebody can help me

2

What do you have connected to the Rx pin of Serial2?

3

nothing, i thought it would not be a problem using analog pins like i show because im using libraries of the MQ7 and MG811 sensors

4

How do you expect a UART port to be of any use without a device connected to it?

5

Then why have you made the reading of the sensor on A0 dependent upon something available to read at Serial2

6

The Mega has 4 UARTs (serial ports). The UART (Serial) is connected to

  1. Pins 0 and 1
  2. A serial-to-usb converter for communication with the PC

The other UARTs are connected to other pins and are not connected to a / the serial-to-usb converter. So there is no way that Serial1, Serial2 and Serial3 can communicate with a PC unless you add external serial-to-usb adapters and connect those to a / the PC.

7

Ty, i wasn't sure about that fact, then i need to change some parts of my code to use the serial 2, I hope i can send the data of Rx 2 to the LCD. At first i use serial 0 to communicate my FPGA Artix 7, now i will change to UART 2

8

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