Stick-V

import time
from machine import UART
from fpioa_manager import fm

fm.register(35, fm.fpioa.UART2_TX, force=True)
fm.register(34, fm.fpioa.UART2_RX, force=True)
uart = UART(UART.UART2, 9600)

while(True):
uart.write("Hello World!\r")
time.sleep(1000)

Stack-Fire

#include <M5Stack.h> // needed for my board M5Stack

HardwareSerial m5stack_uart(2);

void setup()
{
M5.begin();

Serial.begin(9600); ;
m5stack_uart.begin(9600, SERIAL_8N1, 16, 17);
//Serial2_.flush();
Serial.println("Hola");
m5stack_uart.println("Hola");

}

void loop()
{
m5stack_uart.println("@");
if (m5stack_uart.available()) {
String s = m5stack_uart.readString();
Serial.println(s);
}

if (Serial.available()) {
String s = Serial.readString();
m5stack_uart.println(s);
}

}

Regards

Jaime