[Reading UART from arduino]

Can someone please point me in the direction of a tutorial for reading UART from an arduino? Or perhaps point out where I might be going wrong.

I am trying to output a string from TX on the arduino (MKRZERO) and receive it on the analog discovery 2 (AD2).

I am using Digital I/O pin 0 on the AD2 that is connected to the arduino TX pin, and I assume I must also connect the AD2 ground to the arduino ground pin?

 

arduino code here:

#include <Arduino.h>   // required before wiring_private.h
#include "wiring_private.h" // pinPeripheral() function

Uart Serial2 (&sercom2, 3, 4, SERCOM_RX_PAD_1, UART_TX_PAD_0);
void SERCOM2_Handler()
{
  Serial2.IrqHandler();
}

void setup() {
  Serial.begin(115200);

  Serial2.begin(115200);
  
  // Assign pins 3 & 4 SERCOM functionality
  pinPeripheral(3, PIO_SERCOM_ALT);
  pinPeripheral(4, PIO_SERCOM_ALT);
}

uint8_t i=0;
void loop() {
  Serial.print(i);
  Serial2.write(i++);
  if (Serial2.available()) {
    Serial.print(" -> 0x"); Serial.print(Serial2.read(), HEX);
  }
  Serial.println();
  
  delay(500);
}