mcu/types.h
 -  
  #define UART_DEVICE_CNT 1  => #define UART_DEVICE_CNT 2
mcu/serial.c
 - ߰
  extern char uart1_getchar(FILE *f);
  extern void uart1_putchar(char c, FILE *f);
 - 
  uart_init()Լ
  uart1  κп fdevopen(xxx)ּó

main.c
 - ߰
   uart_keyhit(1)