lcdstk.c

CVAVR的函数库的源代码。开发AVR的编译器CodeVision AVR最新版本2.53的函数库c语言源代码。函数短小精悍

/* Alphanumeric LCD driver routines for the
   Kanda Systems STK200+/300 development boards
   
   CodeVisionAVR C Compiler
   (C) 1998-2004 Pavel Haiduc, HP InfoTech S.R.L.

   The LCD is connected in memory mapped mode
   This driver can be used only for AVR chips
   that allow external RAM accessing
*/

#include <delay.h>
#define _LCD_RS0 *(unsigned char *) 0x8000
#define _LCD_RS1 *(unsigned char *) 0xc000

#pragma used+
static unsigned char _base_y[4]={0x80,0xc0};
unsigned char _lcd_x,_lcd_y,_lcd_maxx;
#pragma used-

void _lcd_ready(void)
{
do
  {
  #asm
      ldi   r30,15
      __lcd_delay:
      dec   r30
      brne  __lcd_delay
  #endasm
  }
while (_LCD_RS0 & 0x80);
}

// write a byte to the LCD character generator or display RAM
void lcd_write_byte(unsigned char addr, unsigned char data)
{
_lcd_ready();
_LCD_RS0=addr;
_lcd_ready();
_LCD_RS1=data;
}

// read a byte from the LCD character generator or display RAM
unsigned char lcd_read_byte(unsigned char addr)
{
_lcd_ready();
_LCD_RS0=addr;
_lcd_ready();
return _LCD_RS1;
}

// set the LCD display position x=0..39 y=0..3
void lcd_gotoxy(unsigned char x, unsigned char y)
{
_lcd_ready();
_LCD_RS0=_base_y[y]+x;
_lcd_x=x;
_lcd_y=y;
}

// clear the LCD
void lcd_clear(void)
{
_lcd_ready();
_LCD_RS0=2;   // cursor home
_lcd_ready();
_LCD_RS0=0xc; // cursor off
_lcd_ready();
_LCD_RS0=1;   // clear
_lcd_x=_lcd_y=0;
}

#pragma keep+
void lcd_putchar(char c)
{
#asm
    push r30
    push r31
    ld   r26,y
    set
    cpi  r26,10
    breq __lcd_putchar1
    clt
#endasm
++_lcd_x;
if (_lcd_x>_lcd_maxx)
   {
   #asm("__lcd_putchar1:")
   ++_lcd_y;
   lcd_gotoxy(0,_lcd_y);
   #asm("brts __lcd_putchar0")
   };
_lcd_ready();
_LCD_RS1=c;
#asm
__lcd_putchar0:
    pop  r31
    pop  r30
#endasm
}
#pragma keep-

// write the string str located in SRAM to the LCD
void lcd_puts(char *str)
{
char k;
while (k=*str++) lcd_putchar(k);
}

// write the string str located in FLASH to the LCD
void lcd_putsf(char flash *str)
{
char k;
while (k=*str++) lcd_putchar(k);
}

// initialize the LCD controller
unsigned char lcd_init(unsigned char lcd_columns)
{
#asm
    in   r30,MCUCR
    ori  r30,0xc0
    out  MCUCR,r30
#endasm
_lcd_maxx=lcd_columns;
_base_y[2]=lcd_columns+0x80;
_base_y[3]=lcd_columns+0xc0;
delay_ms(50);
_LCD_RS0=0x38;
delay_ms(5);
_LCD_RS0=0x38;
delay_ms(1);
_LCD_RS0=0x38;
delay_ms(1);
_LCD_RS0=4;
delay_ms(1);
_LCD_RS0=0x85;
delay_ms(1);
if ((_LCD_RS0 & 0xf)!=5) return 0;
_lcd_ready();
_LCD_RS0=6;
lcd_clear();
return 1;
}