/**
* Writes a raw instruction to the LCD.
* @param command The 4-bit instruction code.
* @param data The 8-bit paramater/data to the specified instruction.
*/
void lcd_write_command(unsigned char command, unsigned char data) {
/* Wait for the busy flag to clear */
lcd_wait_busy();
/* Set Enable low, RW low, RS high to write the instruction command */
lcd_enable_low();
lcd_rw_low();
lcd_rs_high();
__asm("nop;"); __asm("nop;"); __asm("nop;");
__asm("nop;"); __asm("nop;"); __asm("nop;");
__asm("nop;"); __asm("nop;"); __asm("nop;");
/* Instruction commands are a maximum of 4 bits long, so
* just mask off the rest. */
LCD_DATA_PORT = (command&0x0F);
lcd_enable_high();
__asm("nop;"); __asm("nop;"); __asm("nop;");
__asm("nop;"); __asm("nop;"); __asm("nop;");
__asm("nop;"); __asm("nop;"); __asm("nop;");
/* Set RW low, RW low to write the instruction data */
lcd_rw_low();
lcd_rs_low();
LCD_DATA_PORT = data;
__asm("nop;"); __asm("nop;"); __asm("nop;");
__asm("nop;"); __asm("nop;"); __asm("nop;");
lcd_strobe_enable();
__asm("nop;"); __asm("nop;"); __asm("nop;");
__asm("nop;"); __asm("nop;"); __asm("nop;");
}
/**
* Initializes the LCD in graphics mode.
* Uses a character pitch of 8 (8 bits are plotted whenever a byte is drawn)
*/
void lcd_graphics_init(void) {
unsigned char commandData;
/* Set the data direction registers apprioriately */
LCD_DATA_DDR = 0xFF;
LCD_CTRL_DDR |= (1<<LCD_CTRL_RS)|(1<<LCD_CTRL_RW)|(1<<LCD_CTRL_E)|(1<<LCD_CTRL_CS)|(1<<LCD_CTRL_RST);
/* Assert all control lines to low */
lcd_rw_low();
lcd_enable_low();
/* Reset the LCD controllers */
lcd_rst_low();
_delay_ms(100); /* Delay for 100 ms */
lcd_rst_high();
_delay_ms(100); /* Delay for 100 ms */
/* Assert all registor control line to low */
lcd_rs_low();
/* Send mode configuration command with
* Toggle Display On, Master, Mode Graphics bits set */
commandData = LCD_MODE_ON_OFF | LCD_MODE_MASTER_SLAVE | LCD_MODE_MODE;
lcd_write_command(LCD_CMD_MODE, commandData);
/* Send the set character pitch command with horizontal
* character pitch of 8 (so 8 pixels are painted when we draw) */
commandData = LCD_CHAR_PITCH_HP_8;
lcd_write_command(LCD_CMD_CHAR_PITCH, commandData);
/* Send the number of characters command with the total
* number of graphics bytes that can be painted horizontally
* (width/8) */
commandData = (LCD_WIDTH/8)-1;
lcd_write_command(LCD_CMD_NUM_CHARS, commandData);
/* Set the time division */
commandData = 128-1;
lcd_write_command(LCD_CMD_TIME_DIVISION, commandData);
/* Set the display low/high start address to 0x00 (left corner) */
commandData = 0x00;
lcd_write_command(LCD_CMD_DISPLAY_START_LA, commandData);
lcd_write_command(LCD_CMD_DISPLAY_START_HA, commandData);
/* Reset the cursor to home 0x00 (left corner) */
commandData = 0x00;
lcd_write_command(LCD_CMD_CURSOR_LA, commandData);
lcd_write_command(LCD_CMD_CURSOR_HA, commandData);
}
/**
* Strobes the Enable control line to trigger the lcd to process the
* transmitted instruction.
*/
void lcd_strobe_enable(void) {
lcd_enable_high();
__asm("nop;"); __asm("nop;"); __asm("nop;");
lcd_enable_low();
__asm("nop;"); __asm("nop;"); __asm("nop;");
}
