serial.c

MANTIS是由科罗拉多大学开发的传感器网络嵌入式操作系统。 这是mantis的0.9.5版本的源码。

//  This file is part of MANTIS OS, Operating System
//  See http://mantis.cs.colorado.edu/
//
//  Copyright (C) 2003,2004,2005 University of Colorado, Boulder
//
//  This program is free software; you can redistribute it and/or
//  modify it under the terms of the mos license (see file LICENSE)

/** @file serial.c
 * @brief Serial functions for the boot loader.
 */

#include "mos.h"
#include "uart.h"

#define FORCEON 0x07
#define FORCEOFF 0x06
#define EN 0x05

/** @brief Initialize for the boot-loader serial connection.
 */
void init_serial()
{
   // Setup default baud rate
   UBRR0H = (uint8_t)(DEFAULT_BAUD_RATE >> 8);
   UBRR0L = (uint8_t)(DEFAULT_BAUD_RATE);

   // enable transmitter and receiver
#ifdef CLOCK_SPEED_4_0
   UCSR0A = (1 << U2X);
#endif
   UCSR0B = (1 << RXEN0) | (1 << TXEN0);
   
   // no parity, 8 bits
   UCSR0C = (3 << UCSZ00);
}

/** @brief Send a byte over the UART.
 * @param c Byte to send
 */
void send_byte(uint8_t c)
{
   while (!(UCSR0A & (1 << UDRE0)));    // wait until reg clear
   UDR0 = c;                    // prepare transmission
}

/** @brief Receive a byte from the UART.
 * @return Byte received
 */
uint8_t recv_byte(void)
{
   while(!(UCSR0A & (1 << RXC0)));  // wait for data
   return UDR0;
}

/** @brief Check to see if data is available from the UART.
 * @return 1 if data is available
 */
int8_t check_recv(void)
{
   if(UCSR0A & (1 << RXC0))
      return 1;
   else
      return 0;
}