Add some utility functions for interfacing with hardware

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

diff --git a/firmware/lcd.c b/firmware/lcd.c
new file mode 100644 (file)
index 0000000..8c722d8
--- /dev/null
+++ b/firmware/lcd.c
@@ -0,0 +1,83 @@
+#include <avr/io.h>
+#include <util/delay.h>
+
+#define USE_SHIFTREG 1
+
+#define NOP() __asm__("nop")
+
+void lcd_init(void);
+void lcd_on(void);
+void lcd_clear(void);
+void lcd_goto(uint8_t);
+void lcd_write(uint8_t);
+
+void lcd_clock(void)
+{
+       _delay_us(1);
+       PORTB |= 0x02;
+       _delay_us(1);
+       PORTB &= ~0x02;
+}
+
+void lcd_set_data(uint8_t d)
+{
+#ifdef USE_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
+}
+
+void lcd_command(uint8_t c)
+{
+       PORTB &= ~0x01;
+       lcd_set_data(c);
+       lcd_clock();
+}
+
+void lcd_init(void)
+{
+       DDRB |= 0x0F;
+       PORTB &= ~0x0F;
+       _delay_ms(20);
+       lcd_command(0x38);
+       _delay_us(50);
+}
+
+void lcd_on(void)
+{
+       lcd_command(0x0C);
+       _delay_us(50);
+}
+
+void lcd_clear(void)
+{
+       lcd_command(0x01);
+       _delay_us(1500);
+}
+
+void lcd_gotoxy(uint8_t x, uint8_t y)
+{
+       uint8_t a = x+10*y;
+       if(y&1)
+               a += 54;
+       lcd_command(a|0x80);
+       _delay_us(50);
+}
+
+void lcd_write(uint8_t c)
+{
+       PORTB |= 0x01;
+       lcd_set_data(c);
+       lcd_clock();
+       _delay_us(50);
+}