common/lcd.c

   1 /*
   2 ATMega pinout (with LCD_SHIFTREG):
   3 B0 - HD44780 RS
   4 B1 - HD44780 clock
   5 B2 - shift reg data
   6 B3 - shift reg clock
   7
   8 ATMega pinout (without LCD_SHIFTREG):
   9 D4 - HD44780 RS
  10 D5 - HD44780 clock
  11 D6 - HD44780 data 0
  12 D7 - HD44780 data 1
  13 B0 - HD44780 data 2
  14 B1 - HD44780 data 3
  15 B2 - HD44780 data 4
  16 B3 - HD44780 data 5
  17 B4 - HD44780 data 6
  18 B5 - HD44780 data 7
  19
  20 In both cases, HD44780 R/W needs to be connected to ground.
  21 */
  22 #include <avr/io.h>
  23 #include "delay.h"
  24 #include "lcd.h"
  25 #include "timer.h"
  26
  27 #ifdef LCD_SHIFTREG
  28 #define CLOCK_PORT PORTB
  29 #define CLOCK_BIT 0x02
  30 #define REGSEL_PORT PORTB
  31 #define REGSEL_BIT 0x01
  32 #else
  33 #define CLOCK_PORT PORTD
  34 #define CLOCK_BIT 0x20
  35 #define REGSEL_PORT PORTD
  36 #define REGSEL_BIT 0x10
  37 #endif
  38
  39 #ifndef LCD_BUFSIZE
  40 #define LCD_BUFSIZE 32
  41 #endif
  42
  43 #define NOP() __asm__("nop")
  44
  45 #ifdef LCD_ASYNC
  46 static volatile uint8_t lcd_busy = 0;
  47 static uint8_t lcd_buffer[LCD_BUFSIZE];
  48 static volatile uint8_t lcd_buf_head = 0;
  49 static volatile uint8_t lcd_buf_tail = 0;
  50 #endif
  51
  52 static void lcd_clock(void)
  53 {
  54         delay_us(1);
  55         CLOCK_PORT |= CLOCK_BIT;
  56         delay_us(1);
  57         CLOCK_PORT &= ~CLOCK_BIT;
  58 }
  59
  60 static void lcd_set_data(uint8_t d)
  61 {
  62 #ifdef LCD_SHIFTREG
  63         for(uint8_t i=0; i<8; ++i)
  64         {
  65                 PORTB = (PORTB&~0x04)|((d&1)<<2);
  66                 PORTB |= 0x08;
  67                 NOP();
  68                 PORTB &= ~0x08;
  69                 d >>= 1;
  70         }
  71 #else
  72         PORTD = (PORTD&0x3F) | (d<<6);
  73         PORTB = (PORTB&0xC0) | (d>>2);
  74 #endif
  75 }
  76
  77 static void lcd_command(uint8_t c)
  78 {
  79         REGSEL_PORT &= ~REGSEL_BIT;
  80         lcd_set_data(c);
  81         lcd_clock();
  82 }
  83
  84 static void lcd_delay(uint16_t us)
  85 {
  86 #ifdef LCD_ASYNC
  87         lcd_busy = 1;
  88         timer_start_us(0, us);
  89 #else
  90         delay_us(us);
  91 #endif
  92 }
  93
  94 #ifdef LCD_ASYNC
  95 static void lcd_wait(void)
  96 {
  97         while(lcd_busy) ;
  98 }
  99
 100 static void lcd_buffer_push(uint8_t byte)
 101 {
 102         while((lcd_buf_head+1)%sizeof(lcd_buffer)==lcd_buf_tail) ;
 103         lcd_buffer[lcd_buf_head] = byte;
 104         lcd_buf_head = (lcd_buf_head+1)%sizeof(lcd_buffer);
 105 }
 106
 107 static uint8_t lcd_buffer_pop(void)
 108 {
 109         uint8_t byte = lcd_buffer[lcd_buf_tail];
 110         lcd_buf_tail = (lcd_buf_tail+1)%sizeof(lcd_buffer);
 111         return byte;
 112 }
 113
 114 static void lcd_timer(void)
 115 {
 116         if(lcd_busy)
 117         {
 118                 if(lcd_buf_head!=lcd_buf_tail)
 119                 {
 120                         uint8_t byte = lcd_buffer_pop();
 121                         if(byte==0xFF)
 122                         {
 123                                 REGSEL_PORT |= REGSEL_BIT;
 124                                 byte = lcd_buffer_pop();
 125                         }
 126                         else if(byte>=0x80)
 127                                 REGSEL_PORT &= ~REGSEL_BIT;
 128                         else
 129                                 REGSEL_PORT |= REGSEL_BIT;
 130                         lcd_set_data(byte);
 131                         lcd_clock();
 132                         lcd_delay(50);
 133                 }
 134                 else
 135                 {
 136                         lcd_busy = 0;
 137                         timer_stop(0);
 138                 }
 139         }
 140 }
 141
 142 TIMER_SET_CALLBACK(0, lcd_timer)
 143 #endif
 144
 145 void lcd_init(void)
 146 {
 147 #ifdef LCD_SHIFTREG
 148         DDRB |= 0x0F;
 149         PORTB &= ~0x0F;
 150 #else
 151         DDRD |= 0xF0;
 152         PORTD &= ~0xF0;
 153         DDRB |= 0x3F;
 154         PORTB &= ~0x3F;
 155 #endif
 156
 157         delay_ms(20);
 158         lcd_command(0x38);
 159         delay_us(50);
 160         lcd_command(0x0C);
 161         delay_us(50);
 162 }
 163
 164 void lcd_clear(void)
 165 {
 166 #ifdef LCD_ASYNC
 167         lcd_wait();
 168 #endif
 169         lcd_command(0x01);
 170         lcd_delay(1700);
 171 }
 172
 173 void lcd_gotoxy(uint8_t x, uint8_t y)
 174 {
 175         uint8_t a = x+10*y;
 176         if(y&1)
 177                 a += 54;
 178
 179 #ifdef LCD_ASYNC
 180         if(lcd_busy)
 181         {
 182                 lcd_buffer_push(a|0x80);
 183                 return;
 184         }
 185 #endif
 186
 187         lcd_command(a|0x80);
 188         lcd_delay(50);
 189 }
 190
 191 void lcd_write(uint8_t c)
 192 {
 193 #ifdef LCD_ASYNC
 194         if(lcd_busy)
 195         {
 196                 if(c>=0x80)
 197                         lcd_buffer_push(0xFF);
 198                 lcd_buffer_push(c);
 199                 return;
 200         }
 201 #endif
 202
 203         REGSEL_PORT |= REGSEL_BIT;
 204         lcd_set_data(c);
 205         lcd_clock();
 206         lcd_delay(50);
 207 }