// // hello.LCD.44.c // // LCD hello-world // // set lfuse to 0x5E for 20 MHz xtal // // Neil Gershenfeld // 11/14/10 // // (c) Massachusetts Institute of Technology 2010 // This work may be reproduced, modified, distributed, // performed, and displayed for any purpose. Copyright is // retained and must be preserved. The work is provided // as is; no warranty is provided, and users accept all // liability. // #include #include #include #define output(directions,pin) (directions |= pin) // set port direction for output #define set(port,pin) (port |= pin) // set port pin #define clear(port,pin) (port &= (~pin)) // clear port pin #define pin_test(pins,pin) (pins & pin) // test for port pin #define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set #define LCD_port PORTA #define LCD_direction DDRA #define DB7 (1 << PA0) #define DB6 (1 << PA1) #define DB5 (1 << PA2) #define DB4 (1 << PA3) #define E (1 << PA4) #define RS (1 << PA5) #define long_delay() _delay_ms(1000) // delay before redraw #define lcd_delay() _delay_ms(10) // delay between commands #define strobe_delay() _delay_us(1) // delay for strobe // // lcd_putchar // put character in lcdbyte // void lcd_putchar(char lcdbyte) { // // set RS for data // set(LCD_port, RS); // // output high nibble // if bit_test(lcdbyte, 7) set(LCD_port, DB7); else clear(LCD_port, DB7); if bit_test(lcdbyte, 6) set(LCD_port, DB6); else clear(LCD_port, DB6); if bit_test(lcdbyte, 5) set(LCD_port, DB5); else clear(LCD_port, DB5); if bit_test(lcdbyte, 4) set(LCD_port, DB4); else clear(LCD_port, DB4); // // strobe E // strobe_delay(); set(LCD_port, E); strobe_delay(); clear(LCD_port, E); // // wait // lcd_delay(); // // output low nibble // if bit_test(lcdbyte, 3) set(LCD_port, DB7); else clear(LCD_port, DB7); if bit_test(lcdbyte, 2) set(LCD_port, DB6); else clear(LCD_port, DB6); if bit_test(lcdbyte, 1) set(LCD_port, DB5); else clear(LCD_port, DB5); if bit_test(lcdbyte, 0) set(LCD_port, DB4); else clear(LCD_port, DB4); // // strobe E // strobe_delay(); set(LCD_port, E); strobe_delay(); clear(LCD_port, E); // // wait and return // lcd_delay(); } // // lcd_putcmd // put command in lcdbyte // void lcd_putcmd(char lcdbyte) { // // clear RS for command // clear(LCD_port, RS); // // output command bits // PORTA = lcdbyte; // // strobe E // strobe_delay(); set(LCD_port, E); strobe_delay(); clear(LCD_port, E); // // wait and return // lcd_delay(); } // // lcd_putstring // put a null-terminated string in flash // void lcd_putstring(PGM_P message) { static uint8_t index; static char chr; index = 0; while (1) { chr = pgm_read_byte(&(message[index])); if (chr == 0) return; lcd_putchar(chr); ++index; } } // // lcd_init // initialize the LCD // void lcd_init() { // // power-up delay // lcd_delay(); // // initialization sequence // lcd_putcmd(DB5+DB4); lcd_putcmd(DB5+DB4); lcd_putcmd(DB5+DB4); // // 4-bit interface // lcd_putcmd(DB5); // // two lines, 5x7 font // lcd_putcmd(DB5); lcd_putcmd(DB7); // // display on // lcd_putcmd(0); lcd_putcmd(DB7+DB6+DB5); // // entry mode // lcd_putcmd(0); lcd_putcmd(DB6+DB5); } int main(void) { // // main // // set clock divider to /1 // CLKPR = (1 << CLKPCE); CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0); // // initialize LCD pins // clear(LCD_port, DB7); output(LCD_direction, DB7); clear(LCD_port, DB6); output(LCD_direction, DB6); clear(LCD_port, DB5); output(LCD_direction, DB5); clear(LCD_port, DB4); output(LCD_direction, DB4); clear(LCD_port, E); output(LCD_direction, E); clear(LCD_port, RS); output(LCD_direction, RS); // // initialize LCD // lcd_init(); // // main loop // while (1) { // // go to zero position // lcd_putcmd(0); lcd_putcmd(DB5); // // print first line from flash // static const char line1[] PROGMEM = "Hello to"; lcd_putstring((PGM_P) line1); // // move to second line // lcd_putcmd(DB7+DB6); lcd_putcmd(0); // // print second line from flash // static const char line2[] PROGMEM = "the world"; lcd_putstring((PGM_P) line2); // // pause // long_delay(); // // clear display // lcd_putcmd(0); lcd_putcmd(DB4); } }