lcd4x40.c

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/*
  LCD driver routines for 4x40 alphanumeric LCD 

  CodeVisionAVR C Compiler
  (C) 1998-2004 Pavel Haiduc, HP InfoTech S.R.L.
*/

#asm
    .equ __lcd_direction=__lcd_port-1
    .equ __lcd_pin=__lcd_port-2
    .equ __lcd_rs=0
    .equ __lcd_rd=1
    .equ __lcd_enable1=2
    .equ __lcd_enable2=3
    .equ __lcd_busy_flag=7
#endasm

#define LCD_MAXX 40

#define LCD_EN1 4
#define LCD_EN2 8

#pragma used+
#pragma regalloc-
unsigned char _en1_msk;
#pragma regalloc+
unsigned char _lcd_x,_lcd_y;
#pragma used-

static void _lcd_delay(void)
{
#asm
    ldi   r31,15
__lcd_delay0:
    dec   r31
    brne  __lcd_delay0
#endasm
}

void _lcd_ready(void)
{
#asm
    ldi   r26,0xf                 ;set as input
    out   __lcd_direction,r26
    sbi   __lcd_port,__lcd_rd     ;RD=1
    cbi   __lcd_port,__lcd_rs     ;RS=0
    in    r26,__lcd_port
    lds   r27,__en1_msk
__lcd_busy:
#endasm
_lcd_delay();
#asm
    or    r26,r27
    out   __lcd_port,r26          ;EN=1
#endasm
_lcd_delay();
#asm
    in    r30,__lcd_pin
    andi  r26,0xf3
    out   __lcd_port,r26          ;EN=0
#endasm
_lcd_delay();
#asm
    or    r26,r27
    out   __lcd_port,r26          ;EN=1
#endasm
_lcd_delay();
#asm
    andi  r26,0xf3
    out   __lcd_port,r26          ;EN=0
#endasm
_lcd_delay();
#asm
    sbrc  r30,__lcd_busy_flag
    rjmp  __lcd_busy
#endasm
}

static void _lcd_write_nibble(void)
{
#asm
    andi  r26,0xf0
    or    r26,r27
    out   __lcd_port,r26          ;write
    or    r26,r30
    out   __lcd_port,r26          ;EN=1
#endasm
_lcd_delay();
#asm
    andi  r26,0xf3
    out   __lcd_port,r26          ;EN=0
#endasm
_lcd_delay();
}

void _lcd_write_data(unsigned char data)
{
#asm
    cbi  __lcd_port,__lcd_rd 	  ;RD=0
    ldi   r26,0xff                ;set as output
    out   __lcd_direction,r26
    lds   r30,__en1_msk
    in    r27,__lcd_port
    andi  r27,0xf
    ld    r26,y
#endasm
_lcd_write_nibble();              //RD=0, write MSN
#asm
    ld    r26,y
    swap  r26
#endasm
_lcd_write_nibble();              //write LSN
#asm
    sbi   __lcd_port,__lcd_rd     ;RD=1
#endasm
}

// write a byte to the LCD character generator or display RAM
void lcd_write_byte(unsigned char addr, unsigned char data)
{
_lcd_ready();
_lcd_write_data(addr);
_lcd_ready();
#asm
    sbi   __lcd_port,__lcd_rs     ;RS=1
#endasm
_lcd_write_data(data);
}

static void _lcd_read_nibble(void)
{
#asm
    in    r27,__lcd_port
    lds   r30,__en1_msk
    or    r27,r30
    out   __lcd_port,r27          ;EN=1
#endasm
_lcd_delay();
#asm
    in    r30,__lcd_pin           ;read
    andi  r27,0xf3
    out   __lcd_port,r27          ;EN=0
#endasm
_lcd_delay();
#asm
    andi  r30,0xf0
#endasm
}

static unsigned char lcd_read_byte0(void)
{
_lcd_delay();
_lcd_read_nibble();               //read MSN
#asm
    mov   r26,r30
#endasm
_lcd_read_nibble();               //read LSN
#asm
    cbi   __lcd_port,__lcd_rd     ;RD=0
    swap  r30
    or    r30,r26
#endasm
}

// read a byte from the LCD character generator or display RAM
unsigned char lcd_read_byte(unsigned char addr)
{
_lcd_ready();
_lcd_write_data(addr);
_lcd_ready();
#asm
    ldi   r26,0xf                 ;set as input
    out   __lcd_direction,r26
    sbi   __lcd_port,__lcd_rs     ;RS=1
#endasm
return lcd_read_byte0();
}

// set the LCD display position x=0..39 y=0..3
void lcd_gotoxy(unsigned char x, unsigned char y)
{
unsigned char base_y;
_en1_msk=LCD_EN1;
if (y>1) _en1_msk=LCD_EN2;
base_y=0x80+x;
if (y&1) base_y|=0x40;
_lcd_ready(); // RS=0
_lcd_write_data(base_y);
_lcd_x=x;
_lcd_y=y;
}

// clear the LCD
void lcd_clear1(void)
{
_lcd_ready();         // RS=0
_lcd_write_data(2);   // cursor home
_lcd_ready();
_lcd_write_data(0xc); // cursor off
_lcd_ready();
_lcd_write_data(1);   // clear
}

void lcd_clear(void)
{
_en1_msk=LCD_EN2;
lcd_clear1();
_en1_msk=LCD_EN1;
lcd_clear1();
_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")
   };
#asm
    rcall __lcd_ready
    sbi  __lcd_port,__lcd_rs ;RS=1
    ld   r26,y
    st   -y,r26
    rcall __lcd_write_data
__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);
}

void _long_delay(void)
{
#asm
    clr   r26
    clr   r27
__long_delay0:
    sbiw  r26,1         ;2 cycles
    brne  __long_delay0 ;2 cycles
#endasm
}

static void _lcd_init_write(unsigned char data)
{
#asm
    cbi  __lcd_port,__lcd_rd 	  ;RD=0
    ldi   r26,0xff                ;set as output
    out   __lcd_direction,r26
    lds   r30,__en1_msk
    in    r27,__lcd_port
    andi  r27,0xf
    ld    r26,y
#endasm
_lcd_write_nibble();              //RD=0, write MSN
#asm
    sbi   __lcd_port,__lcd_rd     ;RD=1
#endasm
}

static unsigned char lcd_init1(void)
{
_long_delay();
_lcd_init_write(0x30);
_long_delay();
_lcd_init_write(0x30);
_long_delay();
_lcd_init_write(0x30);
_long_delay();
_lcd_init_write(0x20);
_long_delay();
_lcd_write_data(0x28);
_long_delay();
_lcd_write_data(4);
_long_delay();
_lcd_write_data(0x85);
_long_delay();
#asm
    in    r26,__lcd_direction
    andi  r26,0xf                 ;set as input
    out   __lcd_direction,r26
    sbi   __lcd_port,__lcd_rd     ;RD=1
#endasm
if (lcd_read_byte0()!=5) return 0;
_lcd_ready();
_lcd_write_data(6);
return 1;
}

// initialize the LCD controller
unsigned char lcd_init(void)
{
#asm
    cbi   __lcd_port,__lcd_enable1 ;EN1=0
    cbi   __lcd_port,__lcd_enable2 ;EN2=0
    cbi   __lcd_port,__lcd_rs      ;RS=0
#endasm
_en1_msk=LCD_EN1;
if (!lcd_init1()) return 0;
_en1_msk=LCD_EN2;
if (!lcd_init1()) return 0;
lcd_clear();
return 1;
}