firmware/lcd.c

   1 /* $Id$
   2
   3 This file is part of the MSP Märklin suite
   4 Copyright © 2010  Mikkosoft Productions, Mikko Rasa
   5 Distributed under the GPL
   6
   7 ATMega pinout (with LCD_SHIFTREG):
   8 B0 - HD44780 RS
   9 B1 - HD44780 clock
  10 B2 - shift reg data
  11 B3 - shift reg clock
  12
  13 ATMega pinout (without LCD_SHIFTREG):
  14 D4 - HD44780 RS
  15 D5 - HD44780 clock
  16 D6 - HD44780 data 0
  17 D7 - HD44780 data 1
  18 B0 - HD44780 data 2
  19 B1 - HD44780 data 3
  20 B2 - HD44780 data 4
  21 B3 - HD44780 data 5
  22 B4 - HD44780 data 6
  23 B5 - HD44780 data 7
  24
  25 In both cases, HD44780 R/W needs to be connected to ground.
  26 */
  27 #include <avr/io.h>
  28 #include "delay.h"
  29 #include "lcd.h"
  30 #include "timer.h"
  31
  32 #ifdef LCD_SHIFTREG
  33 #define CLOCK_PORT PORTB
  34 #define CLOCK_BIT 0x02
  35 #define REGSEL_PORT PORTB
  36 #define REGSEL_BIT 0x01
  37 #else
  38 #define CLOCK_PORT PORTD
  39 #define CLOCK_BIT 0x20
  40 #define REGSEL_PORT PORTD
  41 #define REGSEL_BIT 0x10
  42 #endif
  43
  44 #ifndef LCD_BUFSIZE
  45 #define LCD_BUFSIZE 32
  46 #endif
  47
  48 #define NOP() __asm__("nop")
  49
  50 #ifdef LCD_ASYNC
  51 static volatile uint8_t lcd_busy = 0;
  52 static uint8_t lcd_buffer[LCD_BUFSIZE];
  53 static volatile uint8_t lcd_buf_head = 0;
  54 static volatile uint8_t lcd_buf_tail = 0;
  55 #endif
  56
  57 static void lcd_clock(void)
  58 {
  59         delay_us(1);
  60         CLOCK_PORT |= CLOCK_BIT;
  61         delay_us(1);
  62         CLOCK_PORT &= ~CLOCK_BIT;
  63 }
  64
  65 static void lcd_set_data(uint8_t d)
  66 {
  67 #ifdef LCD_SHIFTREG
  68         uint8_t i;
  69         for(i=0; i<8; ++i)
  70         {
  71                 PORTB = (PORTB&~0x04)|((d&1)<<2);
  72                 PORTB |= 0x08;
  73                 NOP();
  74                 PORTB &= ~0x08;
  75                 d >>= 1;
  76         }
  77 #else
  78         PORTD = (PORTD&0x3F) | (d<<6);
  79         PORTB = (PORTB&0xC0) | (d>>2);
  80 #endif
  81 }
  82
  83 static void lcd_command(uint8_t c)
  84 {
  85         REGSEL_PORT &= ~REGSEL_BIT;
  86         lcd_set_data(c);
  87         lcd_clock();
  88 }
  89
  90 static void lcd_delay(uint16_t us)
  91 {
  92 #ifdef LCD_ASYNC
  93         lcd_busy = 1;
  94         timer_start_us(0, us);
  95 #else
  96         delay_us(us);
  97 #endif
  98 }
  99
 100 #ifdef LCD_ASYNC
 101 static void lcd_wait(void)
 102 {
 103         while(lcd_busy) ;
 104 }
 105
 106 static void lcd_buffer_push(uint8_t byte)
 107 {
 108         while((lcd_buf_head+1)%sizeof(lcd_buffer)==lcd_buf_tail) ;
 109         lcd_buffer[lcd_buf_head] = byte;
 110         lcd_buf_head = (lcd_buf_head+1)%sizeof(lcd_buffer);
 111 }
 112
 113 static uint8_t lcd_buffer_pop(void)
 114 {
 115         uint8_t byte = lcd_buffer[lcd_buf_tail];
 116         lcd_buf_tail = (lcd_buf_tail+1)%sizeof(lcd_buffer);
 117         return byte;
 118 }
 119
 120 static void lcd_timer(void)
 121 {
 122         if(lcd_busy)
 123         {
 124                 if(lcd_buf_head!=lcd_buf_tail)
 125                 {
 126                         uint8_t byte = lcd_buffer_pop();
 127                         if(byte==0xFF)
 128                         {
 129                                 REGSEL_PORT |= REGSEL_BIT;
 130                                 byte = lcd_buffer_pop();
 131                         }
 132                         else if(byte>=0x80)
 133                                 REGSEL_PORT &= ~REGSEL_BIT;
 134                         else
 135                                 REGSEL_PORT |= REGSEL_BIT;
 136                         lcd_set_data(byte);
 137                         lcd_clock();
 138                         lcd_delay(50);
 139                 }
 140                 else
 141                 {
 142                         lcd_busy = 0;
 143                         timer_stop(0);
 144                 }
 145         }
 146 }
 147
 148 TIMER_SET_CALLBACK(0, lcd_timer)
 149 #endif
 150
 151 void lcd_init(void)
 152 {
 153 #ifdef LCD_SHIFTREG
 154         DDRB |= 0x0F;
 155         PORTB &= ~0x0F;
 156 #else
 157         DDRD |= 0xF0;
 158         PORTD &= ~0xF0;
 159         DDRB |= 0x3F;
 160         PORTB &= ~0x3F;
 161 #endif
 162
 163         delay_ms(20);
 164         lcd_command(0x38);
 165         delay_us(50);
 166         lcd_command(0x0C);
 167         delay_us(50);
 168 }
 169
 170 void lcd_clear(void)
 171 {
 172 #ifdef LCD_ASYNC
 173         lcd_wait();
 174 #endif
 175         lcd_command(0x01);
 176         lcd_delay(1700);
 177 }
 178
 179 void lcd_gotoxy(uint8_t x, uint8_t y)
 180 {
 181         uint8_t a = x+10*y;
 182         if(y&1)
 183                 a += 54;
 184
 185 #ifdef LCD_ASYNC
 186         if(lcd_busy)
 187         {
 188                 lcd_buffer_push(a|0x80);
 189                 return;
 190         }
 191 #endif
 192
 193         lcd_command(a|0x80);
 194         lcd_delay(50);
 195 }
 196
 197 void lcd_write(uint8_t c)
 198 {
 199 #ifdef LCD_ASYNC
 200         if(lcd_busy)
 201         {
 202                 if(c>=0x80)
 203                         lcd_buffer_push(0xFF);
 204                 lcd_buffer_push(c);
 205                 return;
 206         }
 207 #endif
 208
 209         REGSEL_PORT |= REGSEL_BIT;
 210         lcd_set_data(c);
 211         lcd_clock();
 212         lcd_delay(50);
 213 }