UART

Data Structures
struct	USART_config
	USART configuration structure. More...

Functions
int	USART_init (struct USART_config *config)
	Initialize USART0 with the given configuration.
int	USART_endl (void)
	Transmit CRLF as end-of-line.
int	USART_Transmit (unsigned char data)
	Transmit a single byte via USART0.
int	USART_SendString (char data[])
	Send a zero-terminated string over USART0.
int	USART_Receive (void)
	Receive one byte from USART0. (Minimal implementation.).
int	USART_ReceiveHandler (void)
	Handle incoming received bytes and simple command echoing.

Detailed Description

Function Documentation

USART_endl()

int USART_endl

(

void

)

#include <uart.h>

Transmit CRLF as end-of-line.

Returns

Status code from last character transmitted.

Definition at line 32 of file uart.c.

                     {
  int status = 0;
  status = USART_Transmit('\x0D');
  status = USART_Transmit('\x0A');
  return status;
}

USART_init()

int USART_init

(

struct USART_config *

config

)

#include <uart.h>

Initialize USART0 with the given configuration.

Enables TX and RX with frame format 8N1. TODO: Verify...

Parameters

[in]

config

Pointer to configuration containing baud rate and clock.

Returns

0 on success, non-zero on error.

Definition at line 15 of file uart.c.

                                            {
  uint16_t ubrr = (config->fosc / 16 / config->baud) - 1;
  UBRR0H = (unsigned char)(ubrr >> 8);
  UBRR0L = (unsigned char)ubrr;
 
  // Enable RX & TX & RXC interrupt
  UCSR0B = (1 << RXEN0) | (1 << TXEN0) /*| (1 << RXCIE0)*/;
 
  // Format 9600 8N1
  UCSR0C = (1 << URSEL0) | (0 << USBS0) | (3 << UCSZ00);
 
  // sei();
  // fdevopen(USART_Transmit, USART_Receive);
 
  return 0;
}

Referenced by main().

USART_Receive()

int USART_Receive

(

void

)

#include <uart.h>

Receive one byte from USART0. (Minimal implementation.).

Stores the received byte into a global buffer.

Returns

0 on success.

Definition at line 66 of file uart.c.

                        {
  // Get and return received data from buffer
  receive_buf = UDR0;
 
  return 0;
}

USART_ReceiveHandler()

int USART_ReceiveHandler

(

void

)

#include <uart.h>

Handle incoming received bytes and simple command echoing.

Echoes characters and echos back the full command line when CR is received.

Returns

0 on success.

Definition at line 73 of file uart.c.

                           {
  char cmd[32] = {0};
  int cmd_count = 0;
 
  // Echo
  if (receive_buf) {
    USART_Transmit(receive_buf);
    if (receive_buf == 0x0D) {
      USART_Transmit(0x0A);
    }
 
    cmd[cmd_count] = receive_buf;
    cmd_count++;
    receive_buf = 0;
  }
 
  // CMD Handler
  if (cmd[cmd_count] == 0x0D) {
    USART_SendString(cmd);
    cmd[cmd_count] = 0;
    cmd_count = 0;
  }
 
  return 0;
}

USART_SendString()

int USART_SendString

(

char

data[]

)

#include <uart.h>

Send a zero-terminated string over USART0.

Newlines ('\n') are converted to CRLF.

Parameters

[in]

data

Pointer to zero-terminated string.

Returns

Status code of the last transmitted character.

Referenced by utils_joystick_print_pos(), and utils_joystick_print_raw().

USART_Transmit()

int USART_Transmit

(

unsigned char

data

)

#include <uart.h>

Transmit a single byte via USART0.

Blocks until the transmit buffer is ready.

Parameters

[in]

data

Byte to send.

Returns

0 on success.

Definition at line 39 of file uart.c.

                                       {
  // Wait for empty transmit buffer
  while (!(UCSR0A & (1 << UDRE0)))
    ;
 
  // Put data into buffer, sends the data
  UDR0 = data;
 
  return 0;
}

Referenced by _log_print_P(), USART_endl(), USART_ReceiveHandler(), and USART_SendString().