usrat.h File Reference

USART interface. More...

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Defines
#define	RX_BUFFER_SIZE   4
	USART RX buffer length.
Functions
void	usart_init (uint16_t baudrate)
	Initialize USART, perform fdevopen with uart_putchar.
int	uart_putchar (char data)
	putchar() for USART.
int	uart_getchar ()
	getchar() for USART. Wait for data if not available.
uint8_t	uart_available (void)
	Check data availability in USART buffer.
uint8_t	uart_getc ()
	Nonblocking, nonchecking getchar for USART. Use with care.

---

Detailed Description

USART interface.

---

Define Documentation

#define RX_BUFFER_SIZE   4

USART RX buffer length.

---

Function Documentation

uint8_t uart_available

(

void

)

Check data availability in USART buffer.

Returns:

1 if buffer is not empty.

                         {
    return rx_buffer_in != rx_buffer_out;
}

uint8_t uart_getc

(

)

Nonblocking, nonchecking getchar for USART. Use with care.

                    {
    uint8_t result = rx_buffer[rx_buffer_out];
    rx_buffer_out = (rx_buffer_out + 1) % RX_BUFFER_SIZE;
    
    return result;
}

int uart_getchar

(

)

getchar() for USART. Wait for data if not available.

Returns:

value read.

See also:

uart_available()

                   {
    while (!uart_available());
    
    return (int) uart_getc();
}

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int uart_putchar

(

char

data

)

putchar() for USART.

Parameters:

data

character to print.

                            {
    //while (!(UCSRA & (1<<UDRE))) {};
    if (data == '\n') {
        (void)uart_putchar('\r');
    }

    //PORTD |= 1<<5;
    while (!(UCSRA & (1<<UDRE))) {};
    //PORTD &= (uint8_t)(~(1<<5));

    UDR = (uint8_t)data;

    return 0;
}

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void usart_init

(

uint16_t

baudval

)

Initialize USART, perform fdevopen with uart_putchar.

Parameters:

baudval

(F_CPU/(16*baudrate))-1

See also:

uart_putchar()

                                  {
    // Set baud rate
    UBRRH = (uint8_t)(baudval>>8);
    UBRRL = (uint8_t)baudval;

    rx_buffer_in = rx_buffer_out = 0;

    // Set frame format: 8 data, 1 stop bit
    UCSRC = (uint8_t)((1<<URSEL) | (0<<USBS) | (3<<UCSZ0));
    
    // Enable receiver and transmitter, enable RX complete interrupt
    UCSRB = (uint8_t)((1<<RXEN) | (1<<TXEN) | (1<<RXCIE));

    (void)fdevopen(uart_putchar, NULL/*, 0*/);
}

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