Not receiving from Serial1 on RPI Pico

Hi all. I am trying to communicate via UART0, but It seems I am not receiving anything. I can receive via the micro USB port just fine. My USB to TTL adapter stops flashing a blue light when Serial1.write(" HELLO1 "); is commented out, so I think it is reaching there. In tio I am connected, but nothing is being shown for the adapter, whereas the serial over the micro USB port works fine.

#include <Arduino.h>

// the setup routine runs once when you press reset:
void setup() {
  // initialize the digital pin as an output.


// the loop routine runs over and over again forever:
void loop() {
  Serial.write(" HELLO ");
  Serial1.write(" HELLO1 ");
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);          // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);               // wait for a second
; PlatformIO Project Configuration File
;   Build options: build flags, source filter, extra scripting
;   Upload options: custom port, speed and extra flags
;   Library options: dependencies, extra library storages
; Please visit documentation for the other options and examples
platform =
board = pico
; platform = raspberrypi 
framework = arduino
board_build.core = earlephilhower
board_build.filesystem_size = 0.5m


This should work. Are you sure you’ve hooked up the usb-to-serial adapter right? Maybe swapped RX and TX? GND ↔ GND connected too?

You are right. After swapping them so many times, I had TX and RX mixed up.