// Initialize EBI.
    EBI_Enable( EBI_SDDATAW_8BIT_gc,
                EBI_LPCMODE_ALE1_gc,
                EBI_SRMODE_NOALE_gc,
                EBI_IFMODE_3PORT_gc );

    // Initialize SRAM
    EBI_EnableLPC ( &EBI.CS1,               // Chip Select 1.
                    EBI_CS_ASPACE_128KB_gc, // 128 KB Address space.
                    (void *) SRAM_ADDR,     // Base address.
                    EBI_CS_SRWS_0CLK_gc );

#define    CPU_FREQ                2000000
#define    BAUD_RATE                9600
#define BRREG_VALUE                12

// definition for UART control
#define UART_PORT                PORTF
#define UART_TX_PIN                PIN7_bm
#define BAUD_RATE_LOW_REG        USARTF1.BAUDCTRLA
#define UART_CONTROL_REG        USARTF1.CTRLB
#define ENABLE_TRANSMITTER_BIT    USART_TXEN_bp
#define ENABLE_RECEIVER_BIT        USART_RXEN_bp
#define UART_STATUS_REG            USARTF1.STATUS
#define TRANSMIT_COMPLETE_BIT    USART_TXCIF_bp
#define DATA_REG_EMPTY_BIT        USART_DREIF_bp
#define RECEIVE_COMPLETE_BIT    USART_RXCIF_bp
#define UART_DATA_REG            USARTF1.DATA

/******************************************************************************
* Функция            :
* Описание            :
* Вх. параметры    :
* Возвр. значение    :
*****************************************************************************/
void UART_Init(void)
     {
       UART_PORT.DIRSET |= UART_TX_PIN;
       BAUD_RATE_LOW_REG = BRREG_VALUE;
       UART_CONTROL_REG  = (1<<ENABLE_RECEIVER_BIT)|
                           (1<<ENABLE_TRANSMITTER_BIT);
     }
/******************************************************************************
* Функция            :
* Описание            :
* Вх. параметры    :
* Возвр. значение    :
*****************************************************************************/
void UART_Tx(u08 D)
     {
       UART_DATA_REG = D;
       while(!(UART_STATUS_REG &(1<<TRANSMIT_COMPLETE_BIT)));
       UART_STATUS_REG |= (1<<TRANSMIT_COMPLETE_BIT);
     }
/******************************************************************************
* Функция            :
* Описание            :
* Вх. параметры    :
* Возвр. значение    :
*****************************************************************************/
u08  UART_Rx(void)
     {
       u08 ret=0;
       while(!(UART_STATUS_REG&(1<<RECEIVE_COMPLETE_BIT)));
       //while(bit_is_clear());
       ret = UART_DATA_REG;
       return ret;
     }


int main(void)
     {
       u08 val=0;
      
       //PORTF.DIR = (1<<6) | (1<<7);
       //PORTF.OUT = (1<<6) | (1<<7);
      
       UART_Init();
       for(;;)
         {
          
           val = UART_Rx();
           if(val=='a')
             {
               UART_Tx('Y');
             }
           else if(val=='A')
             {
               UART_Tx('N');
             }
          
           //UART_Tx('*');
         }
     }