firmware/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         uint8_t i;
  64         for(i=0; i<8; ++i)
  65         {
  66                 PORTB = (PORTB&~0x04)|((d&1)<<2);
  67                 PORTB |= 0x08;
  68                 NOP();
  69                 PORTB &= ~0x08;
  70                 d >>= 1;
  71         }
  72 #else
  73         PORTD = (PORTD&0x3F) | (d<<6);
  74         PORTB = (PORTB&0xC0) | (d>>2);
  75 #endif
  76 }
  77
  78 static void lcd_command(uint8_t c)
  79 {
  80         REGSEL_PORT &= ~REGSEL_BIT;
  81         lcd_set_data(c);
  82         lcd_clock();
  83 }
  84
  85 static void lcd_delay(uint16_t us)
  86 {
  87 #ifdef LCD_ASYNC
  88         lcd_busy = 1;
  89         timer_start_us(0, us);
  90 #else
  91         delay_us(us);
  92 #endif
  93 }
  94
  95 #ifdef LCD_ASYNC
  96 static void lcd_wait(void)
  97 {
  98         while(lcd_busy) ;
  99 }
 100
 101 static void lcd_buffer_push(uint8_t byte)
 102 {
 103         while((lcd_buf_head+1)%sizeof(lcd_buffer)==lcd_buf_tail) ;
 104         lcd_buffer[lcd_buf_head] = byte;
 105         lcd_buf_head = (lcd_buf_head+1)%sizeof(lcd_buffer);
 106 }
 107
 108 static uint8_t lcd_buffer_pop(void)
 109 {
 110         uint8_t byte = lcd_buffer[lcd_buf_tail];
 111         lcd_buf_tail = (lcd_buf_tail+1)%sizeof(lcd_buffer);
 112         return byte;
 113 }
 114
 115 static void lcd_timer(void)
 116 {
 117         if(lcd_busy)
 118         {
 119                 if(lcd_buf_head!=lcd_buf_tail)
 120                 {
 121                         uint8_t byte = lcd_buffer_pop();
 122                         if(byte==0xFF)
 123                         {
 124                                 REGSEL_PORT |= REGSEL_BIT;
 125                                 byte = lcd_buffer_pop();
 126                         }
 127                         else if(byte>=0x80)
 128                                 REGSEL_PORT &= ~REGSEL_BIT;
 129                         else
 130                                 REGSEL_PORT |= REGSEL_BIT;
 131                         lcd_set_data(byte);
 132                         lcd_clock();
 133                         lcd_delay(50);
 134                 }
 135                 else
 136                 {
 137                         lcd_busy = 0;
 138                         timer_stop(0);
 139                 }
 140         }
 141 }
 142
 143 TIMER_SET_CALLBACK(0, lcd_timer)
 144 #endif
 145
 146 void lcd_init(void)
 147 {
 148 #ifdef LCD_SHIFTREG
 149         DDRB |= 0x0F;
 150         PORTB &= ~0x0F;
 151 #else
 152         DDRD |= 0xF0;
 153         PORTD &= ~0xF0;
 154         DDRB |= 0x3F;
 155         PORTB &= ~0x3F;
 156 #endif
 157
 158         delay_ms(20);
 159         lcd_command(0x38);
 160         delay_us(50);
 161         lcd_command(0x0C);
 162         delay_us(50);
 163 }
 164
 165 void lcd_clear(void)
 166 {
 167 #ifdef LCD_ASYNC
 168         lcd_wait();
 169 #endif
 170         lcd_command(0x01);
 171         lcd_delay(1700);
 172 }
 173
 174 void lcd_gotoxy(uint8_t x, uint8_t y)
 175 {
 176         uint8_t a = x+10*y;
 177         if(y&1)
 178                 a += 54;
 179
 180 #ifdef LCD_ASYNC
 181         if(lcd_busy)
 182         {
 183                 lcd_buffer_push(a|0x80);
 184                 return;
 185         }
 186 #endif
 187
 188         lcd_command(a|0x80);
 189         lcd_delay(50);
 190 }
 191
 192 void lcd_write(uint8_t c)
 193 {
 194 #ifdef LCD_ASYNC
 195         if(lcd_busy)
 196         {
 197                 if(c>=0x80)
 198                         lcd_buffer_push(0xFF);
 199                 lcd_buffer_push(c);
 200                 return;
 201         }
 202 #endif
 203
 204         REGSEL_PORT |= REGSEL_BIT;
 205         lcd_set_data(c);
 206         lcd_clock();
 207         lcd_delay(50);
 208 }