Use 2 serial usb to uart converters

Projects General Guidance
1

I have an ESP32-S3-Touch-LCD-4.3 from Waveshare (https://www.waveshare.com/wiki/ESP32-S3-Touch-LCD-4.3#Arduino), and I want to connect a GPS module (Ublox NEO 6M) to it. However, this panel does not have a direct connection to UART; instead, it has a USB-C connected to a UART converter. I tried to connect the GPS module using another USB-UART converter.

The connection looks like this:
GPS -> USB-UART -> USB-UART -> Panel

For this connection, I use an external 5V power supply.

Separately, the GPS with the USB-UART converter connected to a computer works, and the panel connected to a computer works. Data goes back and forth for debugging, and I use SSCOM for communication.

pert 2

I moved your topic to a more appropriate forum category @wolfwood1010.

The Nano ESP32 category you chose is only used for discussions directly related to the Arduino Nano ESP32 board.

In the future, please take the time to pick the forum category that best suits the subject of your question. There is an "About the _____ category" topic at the top of each category that explains its purpose.

Thanks in advance for your cooperation.

3

it appears the ESP32-S3-Touch-LCD-4.3 has very restricted access to GPIO pins
are you using the I2C bus connection on GPIO8 and GPIO9?
if not you could try mapping Serial1 to those pins
e.g. this works on a ESP32-S3-DevKitC-1

// ESP32-S3 DevkitC-1  Serial1 test - for loopback test connect pin GPIO8 TXD to pin GPIO9 RXD"
// ss https://docs.espressif.com/projects/esp-idf/en/latest/esp32s3/_images/ESP32-S3_DevKitC-1_pinlayout_v1.1.jpg

#define RXD1 9
#define TXD1 8

void setup() {
  // initialize both serial ports:
  Serial.begin(115200);
  Serial1.begin(9600, SERIAL_8N1, RXD1, TXD1);
  Serial.println();
  Serial.println("\n\nESP32-S3 DevkitC-1 serial1  test pin GPIO8 TXD pin GPIO9 RXD");
  Serial.write("   for loopback test connect pin GPIO8 TXD to pin GPIO9 RXD\n");
}

void loop() {
  // read from port 1, send to port 0:
  if (Serial1.available()) {
    int inByte = Serial1.read();
    Serial.write(inByte);
  }

  // read from port 0, send to port 1:
  if (Serial.available()) {
    int inByte = Serial.read();
    //Serial.write(inByte);
    Serial1.write(inByte);
  }
}

test connecting GPIO8 and GPIO9 to give a loopback

ESP32-S3 DevkitC-1 serial1  test pin GPIO8 TXD pin GPIO9 RXD
   for loopback test connect pin GPIO8 TXD to pin GPIO9 RXD
loopback test 1test 2 1234567890