Just wondering what i am do wrong with arduino nano esp32 uart

Using Arduino Project Guidance
1

I connected the TX1 of the Teensy to the RX0 of the nano esp32 and the RX1 of the Teensy to the TX1 on the nano esp32. I uploaded the following code but the NANO ESP32 output nothing. On the teensy code

void setup() {
  Serial.begin(19200);  // Start serial communication at 19200 bps to match the ESP32 setup
  pinMode(A0, INPUT);   // Set A0 as an input for analog readings
}

void loop() {
  int sensorValue = analogRead(A0);  // Read the analog value from pin A0
  Serial.print("Sensor Value: ");    // Prefix for clarity
  Serial.println(sensorValue);       // Send this value over UART, followed by a newline

  delay(1000);  // Send data every second
}

the monitor is


Sensor Value: 329
Sensor Value: 320
Sensor Value: 308
Sensor Value: 297

On the Nano ESP32, the code is

void setup() {
  // Initialize Serial for debugging
  Serial.begin(19200);  // Change this baud rate if different speeds are required for debugging
  Serial.println("ESP32 UART Debugging Initialized");

  // Initialize Serial2 for main communication
  const int RX2PIN = 16;
  const int TX2PIN = 17;
  Serial2.begin(19200, SERIAL_8N1, RX2PIN, TX2PIN);
  Serial.println("ESP32 UART2 Receiver Initialized on custom pins");
}

void loop() {
  // Check for incoming data on Serial2
  if (Serial2.available()) {
    String incoming = "";
    while (Serial2.available()) {
      delay(2);  // A small delay to buffer the data
      char c = Serial2.read();  // Read incoming character
      incoming += c;  // Append character to string
    }
    if (incoming.length() > 0) {
      Serial.print("Received on UART2: ");
      Serial.println(incoming);
    }
  }
}

and it prints nothing on the serial monitor

2

Did you connect the grounds of the two?

3

And, why then is the ESP32 code looking at Serial2?
I'm not an ESP32 Nano user, but that doesn't sound right.

4

Yes, I connected the grounds.

I tried all the Serial0, Serial1 and Serial2

5

looking at the ESP32 nano pinout I cannot see GPIO16?
try this simple loopback test using GPIO 17 and 18

// ESP32 serial2 hardware loop back test

// see https://circuits4you.com/2018/12/31/esp32-hardware-serial2-example/
/* There are three serial ports on the ESP known as U0UXD, U1UXD and U2UXD.
 * 
 * U0UXD is used to communicate with the ESP32 for programming and during reset/boot.
 * U1UXD is unused and can be used for your projects. Some boards use this port for SPI Flash access though
 * U2UXD is unused and can be used for your projects.
*/


#define RXD2 18
#define TXD2 17

void setup() {
  // Note the format for setting a serial port is as follows: Serial2.begin(baud-rate, protocol, RX pin, TX pin);
  Serial.begin(115200);
  Serial2.begin(115200, SERIAL_8N1, RXD2, TXD2);
  Serial.println("ESP32 hardware serial test on Serial2");
  Serial.println("Serial2 Txd is on pin: " + String(TXD2));
  Serial.println("Serial2 Rxd is on pin: " + String(RXD2));
  Serial.println("For loopback test connect Txd(pin " + String(TXD2) +
                 ") to Rxd(pin " + String(RXD2) + ")");
}

void loop() {  //Choose Serial1 or Serial2 as required
  while (Serial2.available()) {
    Serial.print(char(Serial2.read()));
  }
  while (Serial.available()) {
    Serial2.print(char(Serial.read()));
  }
}

connect 17 to 18 - text entered on keyboard should be echoed to display, e.g.

ESP32 hardware serial test on Serial2
Serial2 Txd is on pin: 17
Serial2 Rxd is on pin: 18
For loopback test connect Txd(pin 17) to Rxd(pin 18)
test1 abcdef
6

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