nuclear@0: #define F_CLK	1000000
nuclear@0: #define F_CPU	1000000
nuclear@0: 
nuclear@0: #include <stdio.h>
nuclear@0: #include <avr/io.h>
nuclear@0: #include <util/delay.h>
nuclear@0: 
nuclear@0: /* hardware setup
nuclear@0:  * - PORT D: data bits
nuclear@0:  * - PORT C
nuclear@0:  *     bit 0: RS
nuclear@0:  *     bit 1: R/W
nuclear@0:  *     bit 2: E
nuclear@0:  */
nuclear@0: 
nuclear@0: #define BIT_RS	3
nuclear@0: #define BIT_RW	4
nuclear@0: #define BIT_E	5
nuclear@0: 
nuclear@0: #define CMD_CLEAR		1
nuclear@0: #define CMD_RET			(1 << 1)
nuclear@0: #define CMD_ENTRY_MODE	(1 << 2)
nuclear@0: #define CMD_ONOFF		(1 << 3)
nuclear@0: #define CMD_SHIFT		(1 << 4)
nuclear@0: #define CMD_FUNC		(1 << 5)
nuclear@0: #define CMD_CGRAM_ADDR	(1 << 6)
nuclear@0: #define CMD_DDRAM_ADDR	(1 << 7)
nuclear@0: 
nuclear@0: #define FUNC_BUS_4BIT	0
nuclear@0: #define FUNC_BUS_8BIT	(1 << 4)
nuclear@0: #define FUNC_LINES_1	0
nuclear@0: #define FUNC_LINES_2	(1 << 3)
nuclear@0: #define FUNC_FONT_5x8	0
nuclear@0: #define FUNC_FONT_5x11	(1 << 2)
nuclear@0: 
nuclear@0: #define ONOFF_DISP			(1 << 2)
nuclear@0: #define ONOFF_CURSOR		(1 << 1)
nuclear@0: #define ONOFF_CURSOR_POS	1
nuclear@0: 
nuclear@0: void setup_adc(void);
nuclear@0: long read_adc(void);
nuclear@0: 
nuclear@0: void lcd_init(void);
nuclear@0: void lcd_clear(void);
nuclear@0: void lcd_set_cursor_addr(unsigned int addr);
nuclear@0: void lcd_putchar(char c);
nuclear@0: void lcd_putstr(const char *str);
nuclear@0: int lcd_stream_write(char c, FILE *fp);
nuclear@0: void lcd_wait_busy(void);
nuclear@0: static void enable(void);
nuclear@0: static void set_bit(int bit);
nuclear@0: static void clear_bit(int bit);
nuclear@0: void delay(int x);
nuclear@0: 
nuclear@0: #define NSDELAY()	asm volatile ("nop")
nuclear@0: #define DEBUG(i)	(PORTB = (1 << (i)))
nuclear@0: 
nuclear@0: FILE stream_lcd = FDEV_SETUP_STREAM(lcd_stream_write, NULL, _FDEV_SETUP_WRITE);
nuclear@0: 
nuclear@0: int main(void)
nuclear@0: {
nuclear@0: 	stdout = stderr = &stream_lcd;
nuclear@0: 
nuclear@0: 	DDRC = 0xfe;
nuclear@0: 	PORTC = 0;	/* disable pullups */
nuclear@0: 
nuclear@0: 	lcd_init();
nuclear@0: 	lcd_clear();
nuclear@0: 
nuclear@0: 	printf("initializing...");
nuclear@0: 	setup_adc();
nuclear@0: 
nuclear@0: 	for(;;) {
nuclear@0: 		long val = read_adc();
nuclear@0: 		double ref = 1.08 * 1.47 / 0.47;
nuclear@0: 		double voltage = ref * (double)val / (double)1024;
nuclear@0: 		lcd_clear();
nuclear@0: 
nuclear@0: 		if(val == 1023) {
nuclear@0: 			printf("*** RANGE ***   ");
nuclear@0: 		} else {
nuclear@0: 			printf("%.2f volts      ", voltage);
nuclear@0: 		}
nuclear@0: 		_delay_ms(500);
nuclear@0: 	}
nuclear@0: 	return 0;
nuclear@0: }
nuclear@0: 
nuclear@0: void setup_adc(void)
nuclear@0: {
nuclear@0: 	/* disable digital input buffer on ADC0 pin */
nuclear@0: 	DIDR0 = 1;
nuclear@0: 
nuclear@0: 	/* use the internal bandgap as a reference */
nuclear@0: 	ADMUX = 3 << REFS0;
nuclear@0: 
nuclear@0: 	/* - enable ADC
nuclear@0: 	 * - set ADC clock prescaler to clock / 8
nuclear@0: 	 */
nuclear@0: 	ADCSRA = (1 << ADEN) | (3 << ADPS0);
nuclear@0: }
nuclear@0: 
nuclear@0: long read_adc(void)
nuclear@0: {
nuclear@0: 	long low;
nuclear@0: 
nuclear@0: 	/* start conversion */
nuclear@0: 	ADCSRA |= (1 << ADSC);
nuclear@0: 
nuclear@0: 	/* wait while converting */
nuclear@0: 	while(ADCSRA & (1 << ADSC));
nuclear@0: 
nuclear@0: 	low = ADCL;
nuclear@0: 	return low | ((long)ADCH << 8);
nuclear@0: }
nuclear@0: 
nuclear@0: void lcd_init(void)
nuclear@0: {
nuclear@0: 	DDRD = 0x0f;	/* port d[0, 3] -> output */
nuclear@0: 
nuclear@0: 	/* make sure the display has time to boot up */
nuclear@0: 	_delay_ms(20);
nuclear@0: 
nuclear@0: 	clear_bit(BIT_RW);
nuclear@0: 
nuclear@0: 	clear_bit(BIT_E);
nuclear@0: 	clear_bit(BIT_RS);
nuclear@0: 	PORTD = CMD_FUNC | FUNC_BUS_8BIT | FUNC_LINES_2 | FUNC_FONT_5x8;
nuclear@0: 	enable();
nuclear@0: 	lcd_wait_busy();
nuclear@0: 
nuclear@0: 	clear_bit(BIT_RS);
nuclear@0: 	PORTD = CMD_ONOFF | ONOFF_DISP | ONOFF_CURSOR;
nuclear@0: 	enable();
nuclear@0: 	lcd_wait_busy();
nuclear@0: 
nuclear@0: 	clear_bit(BIT_RS);
nuclear@0: 	PORTD = CMD_ENTRY_MODE | (1 << 1);
nuclear@0: 	enable();
nuclear@0: 	lcd_wait_busy();
nuclear@0: }
nuclear@0: 
nuclear@0: void lcd_clear(void)
nuclear@0: {
nuclear@0: 	DDRD = 0xff;	/* port d -> output */
nuclear@0: 
nuclear@0: 	clear_bit(BIT_RW);
nuclear@0: 
nuclear@0: 	clear_bit(BIT_E);
nuclear@0: 	clear_bit(BIT_RS);
nuclear@0: 	PORTD = CMD_CLEAR;
nuclear@0: 	enable();
nuclear@0: 	lcd_wait_busy();
nuclear@0: }
nuclear@0: 
nuclear@0: void lcd_set_cursor_addr(unsigned int addr)
nuclear@0: {
nuclear@0: 	DDRD = 0xff;	/* port d -> output */
nuclear@0: 
nuclear@0: 	clear_bit(BIT_RW);
nuclear@0: 
nuclear@0: 	clear_bit(BIT_E);
nuclear@0: 	clear_bit(BIT_RS);
nuclear@0: 	PORTD = CMD_DDRAM_ADDR | addr;
nuclear@0: 	enable();
nuclear@0: 	lcd_wait_busy();
nuclear@0: }
nuclear@0: 
nuclear@0: void lcd_putchar(char c)
nuclear@0: {
nuclear@0: 	DDRD = 0xff;	/* port d -> output */
nuclear@0: 
nuclear@0: 	clear_bit(BIT_RW);
nuclear@0: 
nuclear@0: 	set_bit(BIT_RS);
nuclear@0: 	PORTD = c;
nuclear@0: 	enable();
nuclear@0: 	lcd_wait_busy();
nuclear@0: }
nuclear@0: 
nuclear@0: void lcd_putstr(const char *str)
nuclear@0: {
nuclear@0: 	while(*str) {
nuclear@0: 		lcd_putchar(*str++);
nuclear@0: 	}
nuclear@0: }
nuclear@0: 
nuclear@0: int lcd_stream_write(char c, FILE *fp)
nuclear@0: {
nuclear@0: 	/* TODO terminal shit handling */
nuclear@0: 	lcd_putchar(c);
nuclear@0: 	return 0;
nuclear@0: }
nuclear@0: 
nuclear@0: void lcd_wait_busy(void)
nuclear@0: {
nuclear@0: 	unsigned char data;
nuclear@0: 
nuclear@0: 	DDRD = 0;		/* port d -> input */
nuclear@0: 	PORTD = 0;		/* disable pull-ups */
nuclear@0: 
nuclear@0: 	do {
nuclear@0: 		NSDELAY();
nuclear@0: 		clear_bit(BIT_E);
nuclear@0: 		clear_bit(BIT_RS);
nuclear@0: 		set_bit(BIT_RW);
nuclear@0: 		/*PIND = 0xff;*/
nuclear@0: 
nuclear@0: 		NSDELAY();
nuclear@0: 		set_bit(BIT_E);
nuclear@0: 		NSDELAY();
nuclear@0: 		data = PIND;
nuclear@0: 		clear_bit(BIT_E);
nuclear@0: 		clear_bit(BIT_RW);
nuclear@0: 
nuclear@0: 	} while(data & (1 << 7));
nuclear@0: 
nuclear@0: 	DDRD = 0xff;	/* port d -> output */
nuclear@0: }
nuclear@0: 
nuclear@0: static void enable(void)
nuclear@0: {
nuclear@0: 	NSDELAY();
nuclear@0: 	set_bit(BIT_E);
nuclear@0: 	NSDELAY();
nuclear@0: 	clear_bit(BIT_E);
nuclear@0: 	NSDELAY();
nuclear@0: }
nuclear@0: 
nuclear@0: static void set_bit(int bit)
nuclear@0: {
nuclear@0: 	PORTC |= 1 << bit;
nuclear@0: }
nuclear@0: 
nuclear@0: static void clear_bit(int bit)
nuclear@0: {
nuclear@0: 	PORTC &= ~(1 << bit);
nuclear@0: }
nuclear@0: 
nuclear@0: 
nuclear@0: void delay(int x)
nuclear@0: {
nuclear@0: 	int i, j;
nuclear@0: 
nuclear@0: 	while(x-- > 0) {
nuclear@0: 		for(i=0; i<90; i++) {
nuclear@0: 			for(j=0; j<6; j++) {
nuclear@0: 				asm volatile("nop");
nuclear@0: 			}
nuclear@0: 		}
nuclear@0: 	}
nuclear@0: }