Reorganize the directory structure

[model-railway-devices.git] / common / lcd.c

diff --git a/common/lcd.c b/common/lcd.c
new file mode 100644 (file)
index 0000000..f4e0387
--- /dev/null
+++ b/common/lcd.c
@@ -0,0 +1,208 @@
+/*
+ATMega pinout (with LCD_SHIFTREG):
+B0 - HD44780 RS
+B1 - HD44780 clock
+B2 - shift reg data
+B3 - shift reg clock
+
+ATMega pinout (without LCD_SHIFTREG):
+D4 - HD44780 RS
+D5 - HD44780 clock
+D6 - HD44780 data 0
+D7 - HD44780 data 1
+B0 - HD44780 data 2
+B1 - HD44780 data 3
+B2 - HD44780 data 4
+B3 - HD44780 data 5
+B4 - HD44780 data 6
+B5 - HD44780 data 7
+
+In both cases, HD44780 R/W needs to be connected to ground.
+*/
+#include <avr/io.h>
+#include "delay.h"
+#include "lcd.h"
+#include "timer.h"
+
+#ifdef LCD_SHIFTREG
+#define CLOCK_PORT PORTB
+#define CLOCK_BIT 0x02
+#define REGSEL_PORT PORTB
+#define REGSEL_BIT 0x01
+#else
+#define CLOCK_PORT PORTD
+#define CLOCK_BIT 0x20
+#define REGSEL_PORT PORTD
+#define REGSEL_BIT 0x10
+#endif
+
+#ifndef LCD_BUFSIZE
+#define LCD_BUFSIZE 32
+#endif
+
+#define NOP() __asm__("nop")
+
+#ifdef LCD_ASYNC
+static volatile uint8_t lcd_busy = 0;
+static uint8_t lcd_buffer[LCD_BUFSIZE];
+static volatile uint8_t lcd_buf_head = 0;
+static volatile uint8_t lcd_buf_tail = 0;
+#endif
+
+static void lcd_clock(void)
+{
+       delay_us(1);
+       CLOCK_PORT |= CLOCK_BIT;
+       delay_us(1);
+       CLOCK_PORT &= ~CLOCK_BIT;
+}
+
+static void lcd_set_data(uint8_t d)
+{
+#ifdef LCD_SHIFTREG
+       uint8_t i;
+       for(i=0; i<8; ++i)
+       {
+               PORTB = (PORTB&~0x04)|((d&1)<<2);
+               PORTB |= 0x08;
+               NOP();
+               PORTB &= ~0x08;
+               d >>= 1;
+       }
+#else
+       PORTD = (PORTD&0x3F) | (d<<6);
+       PORTB = (PORTB&0xC0) | (d>>2);
+#endif
+}
+
+static void lcd_command(uint8_t c)
+{
+       REGSEL_PORT &= ~REGSEL_BIT;
+       lcd_set_data(c);
+       lcd_clock();
+}
+
+static void lcd_delay(uint16_t us)
+{
+#ifdef LCD_ASYNC
+       lcd_busy = 1;
+       timer_start_us(0, us);
+#else
+       delay_us(us);
+#endif
+}
+
+#ifdef LCD_ASYNC
+static void lcd_wait(void)
+{
+       while(lcd_busy) ;
+}
+
+static void lcd_buffer_push(uint8_t byte)
+{
+       while((lcd_buf_head+1)%sizeof(lcd_buffer)==lcd_buf_tail) ;
+       lcd_buffer[lcd_buf_head] = byte;
+       lcd_buf_head = (lcd_buf_head+1)%sizeof(lcd_buffer);
+}
+
+static uint8_t lcd_buffer_pop(void)
+{
+       uint8_t byte = lcd_buffer[lcd_buf_tail];
+       lcd_buf_tail = (lcd_buf_tail+1)%sizeof(lcd_buffer);
+       return byte;
+}
+
+static void lcd_timer(void)
+{
+       if(lcd_busy)
+       {
+               if(lcd_buf_head!=lcd_buf_tail)
+               {
+                       uint8_t byte = lcd_buffer_pop();
+                       if(byte==0xFF)
+                       {
+                               REGSEL_PORT |= REGSEL_BIT;
+                               byte = lcd_buffer_pop();
+                       }
+                       else if(byte>=0x80)
+                               REGSEL_PORT &= ~REGSEL_BIT;
+                       else
+                               REGSEL_PORT |= REGSEL_BIT;
+                       lcd_set_data(byte);
+                       lcd_clock();
+                       lcd_delay(50);
+               }
+               else
+               {
+                       lcd_busy = 0;
+                       timer_stop(0);
+               }
+       }
+}
+
+TIMER_SET_CALLBACK(0, lcd_timer)
+#endif
+
+void lcd_init(void)
+{
+#ifdef LCD_SHIFTREG
+       DDRB |= 0x0F;
+       PORTB &= ~0x0F;
+#else
+       DDRD |= 0xF0;
+       PORTD &= ~0xF0;
+       DDRB |= 0x3F;
+       PORTB &= ~0x3F;
+#endif
+
+       delay_ms(20);
+       lcd_command(0x38);
+       delay_us(50);
+       lcd_command(0x0C);
+       delay_us(50);
+}
+
+void lcd_clear(void)
+{
+#ifdef LCD_ASYNC
+       lcd_wait();
+#endif
+       lcd_command(0x01);
+       lcd_delay(1700);
+}
+
+void lcd_gotoxy(uint8_t x, uint8_t y)
+{
+       uint8_t a = x+10*y;
+       if(y&1)
+               a += 54;
+
+#ifdef LCD_ASYNC
+       if(lcd_busy)
+       {
+               lcd_buffer_push(a|0x80);
+               return;
+       }
+#endif
+
+       lcd_command(a|0x80);
+       lcd_delay(50);
+}
+
+void lcd_write(uint8_t c)
+{
+#ifdef LCD_ASYNC
+       if(lcd_busy)
+       {
+               if(c>=0x80)
+                       lcd_buffer_push(0xFF);
+               lcd_buffer_push(c);
+               return;
+       }
+#endif
+
+       REGSEL_PORT |= REGSEL_BIT;
+       lcd_set_data(c);
+       lcd_clock();
+       lcd_delay(50);
+}