lcd.~c

使用iccavr的例子

/* ATmega103 lcd.c file 

   Author : Robert Stuart 
   Company : PDL Industries Ltd 
   Date of Creation : 13 April 2000
   Tested : 13 April 2000
 
   Function : 
   	  This module controls the operation of a 16x2 lcd for the ATmega603/103.
	  
	  Auto detection of lcd added. Reads the last character of each line to 
	  determine whether write was successful.	 
*/

/* include */ 
#include "lcd.h"

/* Initialises the lcd */
void LCDInitialise( void )
{
  MCUCR |= BIT(SRE) | BIT(SRW);			
  LCDCounter = _50MS;         	/* delay counter for lcd initialisation */
  LCDStatus = 0;			/* lcd status flags are reset */
}

/* global function called when writing to the lcd */
void LCDPrintf( char *ptr1, char *ptr2 )
{
  if ( !CHECKBIT( LCDStatus, LCD_UPDATE ) )
  {    	        	         		/* check that lcd is not currently updating */
    strcpy( LCDStr1, ptr1 );		/* copy strings into local variables */ 
    strcpy( LCDStr2, ptr2 );
    
    if ( LCDStr1[0] == CHARACTER_NULL ) /* line 1 not updated */
    {
      strcpy( LCDStr1, LCDStr2 );
      LCDLine = LINE2;
    }
    else if ( LCDStr2[0] == CHARACTER_NULL )
      LCDLine = LINE1;                  /* line 2 not updated */
    else
      LCDLine = LINE1_AND_LINE2;
	  
    SETBIT( LCDStatus, LCD_UPDATE );	/* set flags */
    CLEARBIT( LCDStatus, LCD_QUEUE ); 
  }
  else if ( !CHECKBIT( LCDStatus, LCD_QUEUE ) )
  {    	  	   	          /* update after existing update has been completed */
    strcpy( LCDQueueStr1, ptr1);
    strcpy( LCDQueueStr2, ptr2);
    
    SETBIT( LCDStatus, LCD_QUEUE );
  }
}

/* called from the main 1ms interrupt, must allow at least 40ms before lcd can be initialised */
void DelayLCDStartup( void )
{
  if ( LCDCounter && !CHECKBIT( LCDStatus, LCD_BUSY ) ) 
    LCDCounter--;	 	  	/* count down delay timer */
	
  if ( CHECKBIT( LCDStatus, LCD_INITIALISE ) && LCDCounter == 1 )
    InitScreen();	        		/* initialise lcd */
}

void InitScreen( void )
{
  sprintf( LCDStr1, "%s", LCDHeader1 ); /* initialise lcd lines */
  sprintf( LCDStr2, "%s", LCDHeader2 );
  LCDLine = LINE1_AND_LINE2;	         	/* both lines to be updated */						 
  LCDCounter--;
  SETBIT( LCDStatus, LCD_UPDATE );
}

/* continously called when not serving interrupts and the micro is doing nothing */
void RefreshLCD( void )
{
  if ( CHECKBIT( LCDStatus, LCD_OK ) )	
  { 
    if ( CHECKBIT( LCDStatus, LCD_UPDATE ) )
      WriteToScreen();
  }
  else if ( LCDCounter == _20MS )
    ConfigureLCD();	         		/* configure lcd to 2 lines, 8bit interface */
}

/* sets the lcd to 2-line 16-character mode with 8-bit interface and auto incrementation */
void ConfigureLCD( void )
{
  static const unsigned char initialise_table[] = {FUNCTION_SET, DISPLAY_ON, DISPLAY_CLEAR};
  unsigned char i;
  
  for ( i=0; i<3; i++ )
  {
    CheckIfBusy();
    WriteToDevice( initialise_table[i], INSTRUCTION );	
  }
  
  LCDCounter--;
  SETBIT( LCDStatus, LCD_OK );
  SETBIT( LCDStatus, LCD_INITIALISE );
}

void WriteToScreen( void )
{
  static unsigned char i;
  
  if ( !CHECKBIT( LCDStatus, LCD_BUSY ) )			
  {
    if ( LCDLine == LINE2 )             /* set which line is to be updated */
      WriteToDevice( SECOND_LINE, INSTRUCTION );
    else
      WriteToDevice( FIRST_LINE, INSTRUCTION );
    
    for ( i=0; i<16; i++ )              /* replace all characters after the null which space characters */
      if ( LCDStr1[i] == CHARACTER_NULL )
        for ( ; i<16; i++ )
          LCDStr1[i] = CHARACTER_SPACE;
    i = 0;
    SETBIT( LCDStatus, LCD_BUSY );
  } 

  CheckIfBusy();
  WriteToDevice( LCDStr1[i++], DATA );  /* write character to screen */
  
  if ( i>15 )		          /* finished line */				
  {
    CheckIfBusy();			/* check is lcd is connected */
    if ( LCDLine == LINE2 )
      WriteToDevice( SECOND_LINE, INSTRUCTION );
    else
      WriteToDevice( FIRST_LINE, INSTRUCTION );

    CheckIfBusy();	 	          /* check if first character is correct */
    if ( ReadDevice( DATA ) != LCDStr1[0] )
      LCDInitialise();      	          /* reinitialise lcd otherwise */	  

    if ( LCDLine == LINE1_AND_LINE2 )
    {
      strcpy( LCDStr1, LCDStr2 );    	/* load str2 into str1 and update line 2 */
      LCDLine = LINE2;
    }
    else
    {
      if ( CHECKBIT( LCDStatus, LCD_QUEUE ) )
        LCDPrintf( LCDQueueStr1, LCDQueueStr2 );
          
      CLEARBIT( LCDStatus, LCD_UPDATE );
    }
   
   CLEARBIT( LCDStatus, LCD_BUSY );
  }
}

/* writes to lcd */
void WriteToDevice( char data, unsigned char select )
{
  char *LCD_IO;
  
  if ( select == INSTRUCTION )          /* set RS */
    LCD_IO = ( char * ) 0x8000;		   
  else
    LCD_IO = ( char * ) 0xC000;		   

  *LCD_IO = data;
}

void CheckIfBusy( void )
{
  while ( ReadDevice( INSTRUCTION ) & BUSY_FLAG );
}

/* reads from lcd */
char ReadDevice( unsigned char select )
{
  char *LCD_IO;
  
  if ( select == INSTRUCTION )          /* set RS */
    LCD_IO = ( char * ) 0x8000;			  
  else
    LCD_IO = ( char * ) 0xC000;			  
  
  return *LCD_IO;
}