arduino_stdout_main.cpp

/* 
 * How configure UART to use printf using avr-libc, reference: http://www.nongnu.org/avr-libc/user-manual/index.html
 * This code was compiled using arduino-cmake: 	https://github.com/arduino-cmake/arduino-cmake.git
 * cmake -DINPUT_BOARD=pro -DINPUT_PORT=/dev/ttyUSB0 -DBOARD_CPU=16MHzatmega328 ..
 * make
 * make upload # push reset button before
 */

#if ARDUINO >= 100
    #include "Arduino.h"
#else
    #include "WProgram.h"
#endif

#include <util/delay.h>
#include <stdio.h>

/* UART buffering */
static FILE uartout = { 0 };   // FILE struct
static int uart_putchar(char c, FILE *stream);

// uart_putchar - char output function for printf
static int uart_putchar(char c, FILE *stream)
{
   if( c == '\n' )
      Serial.write('\r');
   Serial.write(c) ;
   return 0 ;
}

void configure_uart()
{
    fdev_setup_stream(&uartout, uart_putchar, NULL, _FDEV_SETUP_WRITE);
    stdout = &uartout;
    printf("setup stdout\n");
}

void setup()
{
    Serial.begin(9600);
    configure_uart();
    Serial.println("setup println");
}

void loop()
{
    while(true)
    {
        printf("loop printf\n");
        Serial.println("loop println");
        _delay_ms(1000);
    }
}