usart.c

DS18B20源代码

/*************************************************************
* Target: usart communication
* File name: usart.c
* Date: 2006.11.19
* Author: Panda
************************************************************/

#include <avr/io.h>
#include <avr/interrupt.h>
#include "usart.h"

#define byte unsigned char
#define word unsigned int

#define CR '/0'
#define BR '/n'

#define pRx &(Rx_Buffer[0])
#define Rx_Buffer_Size 33

static byte Rx_Buffer[Rx_Buffer_Size] ;   //receive buffer
static byte Rx_Ctr = 0;
static byte Rx_Ix = 0;

static byte test_buffer[] = "test!\n"; //test the array sending

static volatile byte *pTx;  //send pointer
static volatile byte Tx_Length = 0; //send length
static byte Tx_Ctr = 0;    // send counter


//串口通信初始化
void usart_init(void)
{
	UCSRB = 0x00;//禁止中断
	UCSRA = 0x00;
	UCSRC = BIT(URSEL) | 0x06;
	UBRRL = 0x0B;
	UBRRH = 0x00;
	UCSRB = 0xD8;
}

/***********************************************
*    The receiving of the usart, by interrupt
************************************************/
SIGNAL(SIG_USART_RECV)
{
 byte temp = UDR;
 if(temp!='r')
 {
   if (Rx_Ix < 32)
   {
   Rx_Ctr++;
   Rx_Buffer[Rx_Ix++] = temp;
   }
  if(Rx_Ix==32)
  {
  Rx_Ix=0;
  Rx_Buffer[32]='\0';
  }
 }
 else if(temp=='r')
 {
 printf(Rx_Buffer);
 //for(temp = 0 ;temp<100;temp++)
 //asm("nop");
 //printf(test_buffer);
 }
}

/************************************************
*  the send of usart, by interrupt
************************************************/
SIGNAL(SIG_USART_TRANS)
{
 if (Tx_Ctr < Tx_Length )
 {
  Tx_Ctr++;   //  the couter of send
  UDR = *(pTx++);  // send data to the sending
 }
 else end_trans();
}

/************************************************
* the interrupt when the UDR is empty
* when the UDR is empty, means that
* you can put the data into the UDR
************************************************/
/*
SIGNAL(SIG_USART_DATA)
{
 if (Comm_Tx_Ctr < Comm_Tx_Size)
  Comm_Tx_Ctr++;   //  the couter of send
  UDR = Comm_Tx_Buf[Comm_Tx_Ix++];  // send data to the sending
  if ( Comm_Tx_Ix == Comm_Tx_Size )
    Comm_Tx_Ix = 0;
}
*/


/**********************************************************
*  send string!
*  2006.11.24
**********************************************************/
void printf(unsigned char * Send_String)
{
  Tx_Length = strlen(Send_String);   //求发送字节数
  pTx = &(Send_String[0]);          //求发送字符串首地址
  Start_trans();                  //开始发送
}


/********************************************************
*  puts char
*  2006.11.26
********************************************************/

void puts(unsigned char data)
{
  while (!(UCSRA & (1<<UDRE)))
  ;
  UDR = data; //也有可能出现傻等的情况，
}


/*********************************************************
* start the transmitt, finish on 2006.11.22
*********************************************************/

void Start_trans(void)
{
  Tx_Ctr = 0;       //情零标志位，从缓冲头开始发送
  while (!(UCSRA & (1<<UDRE)))
  ;
  UDR = *pTx++; //也有可能出现傻等的情况，
  Tx_Ctr++;  //2006.11.22 完成固定缓冲发送，该函数固定。
}

/********************************************************
* end the trans ,finish on 2006.11.22
*********************************************************/
void end_trans(void)
{
 Tx_Length = 0;
 Tx_Ctr = 0;
}

/********************************************************
* handle the data recieved, finish on2006.11.24
*********************************************************/
/*
void handle(void)
{
 unsigned char Ix;
 pRx = &Rx_Buffer[0];
 for ( Ix=0 ; Ix<Rx_Ctr ; Ix++)
 printf(*(pRx+Ix));
}
*/

/////////////////////////////////////////////////////////
//                        end
/////////////////////////////////////////////////////////