RIOT-OS serial comm in arduino m0 pro

main.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "board.h"
#include "msg.h"
#include "thread.h"
#include "periph/uart.h"


#define PC_UART UART_DEV(1)
#define BAUDRATE (115200U)

static kernel_pid_t main_thread_pid;

static void rx_cb(void *uart, uint8_t data)
{
  //printf("receive\n");
  msg_t msg;
  msg.type = (int)uart;
  msg.content.value = (uint32_t)data;

  //printf("[callback]: %d\n", data);
  msg_send(&msg, main_thread_pid);

}

int main(void)
{
  printf("UART test\n");
  printf("=========\n");

  uart_init(PC_UART, BAUDRATE, rx_cb, (void *)PC_UART);

  main_thread_pid = thread_getpid();

  msg_t msg;
  //char* myarray = "ab";
  for(;;)
  {
    msg_receive(&msg);
    printf("[main thread]: %c\n", (char)msg.content.value);
    //uart_write(PC_UART, (const uint8_t*)myarray, strlen(myarray));
  }


  return 0;
}

/*
void setup() {
  Serial1.begin(115200);
  delay(1000);
}

void loop() {
  Serial1.print("a");
  delay(100);
}
*/