lcd.c

来自「8051试验程序 基础教材」· C语言 代码 · 共 141 行

#include <string.h>
#include "target.h"
#include "lcd.h"

#define LCD_COMMAND    LCD_PORT_LOW
#define LCD_CHARACTER  LCD_PORT_HIGH

static void E_pulse()
{
  /* set E high */
  LCD_E = LCD_PORT_HIGH;

  /* delay */
  ms_delay( 10 );

  /* set E low */
  LCD_E = LCD_PORT_LOW;
}

static void set_data( unsigned char data )
{
  LCD_D4 = (data & 0x01) ? 1 : 0;
  LCD_D5 = (data & 0x02) ? 1 : 0;
  LCD_D6 = (data & 0x04) ? 1 : 0;
  LCD_D7 = (data & 0x08) ? 1 : 0;
}

static void send_to_lcd( unsigned char data, unsigned char type )
{
  /* enable write */
  LCD_RW = LCD_PORT_LOW;

  /* 2 ms delay */
  ms_delay( 2 );

  /* set high nibble of command */
  set_data( (data >> 4) );

  /* set RS port to command mode */
  LCD_RS = type;

  /* pulse to set D4-D7 bits  */
  E_pulse();

  /* set low nibble of command */
  set_data( (data & 0x0F) );

  /* set RS port to command mode */
  LCD_RS = type;

  /* pulse to set D4-D7 bits */
  E_pulse();
}

void lcd_init()
{
  /* LCD initialization */
  /* step by step (from Gosho) - from DATASHEET */

  /* clear "command" bits */
  LCD_RS = LCD_PORT_LOW;
  LCD_RW = LCD_PORT_LOW;
  LCD_E  = LCD_PORT_LOW;

  /* 110 ms delay */
  ms_delay( 110 );

  /* set D4 and D5 high */
  LCD_D4 = LCD_PORT_HIGH;
  LCD_D5 = LCD_PORT_HIGH;

  E_pulse();

  /* 10 ms delay */
  ms_delay( 10 );

  /* set D4 and D5 high */
  LCD_D4 = LCD_PORT_HIGH;
  LCD_D5 = LCD_PORT_HIGH;

  E_pulse();

  /* 10 ms delay */
  ms_delay( 10 );

  /* set D4 and D5 high */
  LCD_D4 = LCD_PORT_HIGH;
  LCD_D5 = LCD_PORT_HIGH;

  E_pulse();

  /* 10 ms delay */
  ms_delay( 10 );

  /*  set D4 to low and D5 to high  */
  LCD_D4 = LCD_PORT_LOW;
  LCD_D5 = LCD_PORT_HIGH;

  E_pulse();

  /* enable display */
  send_lcd_command( DISP_ON );

  /* clear display */
  send_lcd_command( CLR_DISP );
}

void lcd_light( unsigned char on )
{
  /* turn on/off lcd light */
  if( on )
  {
    LCD_LIGHT = 1;
  }
  else
  {
    LCD_LIGHT = 0;
  }
}

void send_lcd_command( unsigned char command )
{
  send_to_lcd( command, LCD_COMMAND );
}

void send_lcd_char( unsigned char c )
{
  send_to_lcd( c, LCD_CHARACTER );
}

void send_lcd_text( char* str )
{
  /* loop over string and send each character */
  for( int i=0; i<strlen(str); ++i)
  {
    send_lcd_char( str[i] );
  }
}