1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/pwcdecode.c	Fri Nov 01 09:40:20 2013 +0200
     1.3 @@ -0,0 +1,272 @@
     1.4 +#define F_CLK	1000000
     1.5 +#define F_CPU	1000000
     1.6 +
     1.7 +#include <stdio.h>
     1.8 +#include <avr/io.h>
     1.9 +#include <avr/interrupt.h>
    1.10 +#include <util/delay.h>
    1.11 +
    1.12 +/* hardware setup
    1.13 + * - PORT D: data bits
    1.14 + * - PORT C
    1.15 + *     bit 3: RS
    1.16 + *     bit 4: R/W
    1.17 + *     bit 5: E
    1.18 + */
    1.19 +#define LCD_BUS_WIDTH	8
    1.20 +
    1.21 +#define BIT_RS	3
    1.22 +#define BIT_RW	4
    1.23 +#define BIT_E	5
    1.24 +
    1.25 +#define CMD_CLEAR		1
    1.26 +#define CMD_RET			(1 << 1)
    1.27 +#define CMD_ENTRY_MODE	(1 << 2)
    1.28 +#define CMD_ONOFF		(1 << 3)
    1.29 +#define CMD_SHIFT		(1 << 4)
    1.30 +#define CMD_FUNC		(1 << 5)
    1.31 +#define CMD_CGRAM_ADDR	(1 << 6)
    1.32 +#define CMD_DDRAM_ADDR	(1 << 7)
    1.33 +
    1.34 +#define FUNC_BUS_4BIT	0
    1.35 +#define FUNC_BUS_8BIT	(1 << 4)
    1.36 +#define FUNC_LINES_1	0
    1.37 +#define FUNC_LINES_2	(1 << 3)
    1.38 +#define FUNC_FONT_5x8	0
    1.39 +#define FUNC_FONT_5x11	(1 << 2)
    1.40 +
    1.41 +#define ONOFF_DISP			(1 << 2)
    1.42 +#define ONOFF_CURSOR		(1 << 1)
    1.43 +#define ONOFF_CURSOR_POS	1
    1.44 +
    1.45 +void lcd_init(void);
    1.46 +void lcd_clear(void);
    1.47 +void lcd_set_cursor_addr(unsigned int addr);
    1.48 +void lcd_putchar(char c);
    1.49 +void lcd_putstr(const char *str);
    1.50 +int lcd_stream_write(char c, FILE *fp);
    1.51 +void lcd_wait_busy(void);
    1.52 +static void enable(void);
    1.53 +static void set_bit(int bit);
    1.54 +static void clear_bit(int bit);
    1.55 +void delay(int x);
    1.56 +
    1.57 +#define NSDELAY()	asm volatile ("nop")
    1.58 +#define DEBUG(i)	(PORTB = (1 << (i)))
    1.59 +
    1.60 +FILE stream_lcd = FDEV_SETUP_STREAM(lcd_stream_write, NULL, _FDEV_SETUP_WRITE);
    1.61 +
    1.62 +unsigned int pulse_time;
    1.63 +
    1.64 +int main(void)
    1.65 +{
    1.66 +	stdout = stderr = &stream_lcd;
    1.67 +
    1.68 +	DDRB = 0;	/* set port B as input (bit 0 is used to measure pulse width) */
    1.69 +	PORTB = 0;	/* disable pullups */
    1.70 +
    1.71 +	DDRD = 0xff;
    1.72 +	DDRC = 0xfe;
    1.73 +	PORTC = 0;	/* disable pullups */
    1.74 +
    1.75 +	lcd_init();
    1.76 +	lcd_clear();
    1.77 +
    1.78 +	printf("initializing...");
    1.79 +
    1.80 +	TCCR1B |= (1 << ICES1);	/* set first capture to occur on a rising edge */
    1.81 +	TCCR1B = (TCCR1B & 0xf8) | 1;	/* no prescaling */
    1.82 +	TIMSK1 |= (1 << ICIE1);	/* enable timer1 input capture interrupt */
    1.83 +	sei();
    1.84 +
    1.85 +	for(;;) {
    1.86 +		static int blink = 0;
    1.87 +
    1.88 +		PORTB = blink ? 1 : 0;
    1.89 +		blink = (blink + 1) & 1;
    1.90 +
    1.91 +		lcd_set_cursor_addr(0);
    1.92 +		printf("pulse time: %u us  ", pulse_time);
    1.93 +		lcd_set_cursor_addr(64);
    1.94 +		printf("pos: %u%%          ", (pulse_time - 1000) / 10);
    1.95 +		_delay_ms(100);
    1.96 +	}
    1.97 +	return 0;
    1.98 +}
    1.99 +
   1.100 +ISR(TIMER1_CAPT_vect)
   1.101 +{
   1.102 +	static int rising;
   1.103 +
   1.104 +	rising = !rising;
   1.105 +	if(rising) {
   1.106 +		/* rising edge: reset the timer */
   1.107 +		TCNT1 = 0;
   1.108 +		/* and set a falling edge trigger */
   1.109 +		TCCR1B &= ~(1 << ICES1);
   1.110 +	} else {
   1.111 +		/* falling edge: calculate the time since the last rise */
   1.112 +		pulse_time = ICR1;
   1.113 +		/* and set a rising edge trigger */
   1.114 +		TCCR1B |= 1 << ICES1;
   1.115 +	}
   1.116 +}
   1.117 +
   1.118 +void lcd_write_byte(unsigned char byte)
   1.119 +{
   1.120 +#if LCD_BUS_WIDTH == 8
   1.121 +	DDRD = 0xff;
   1.122 +	PORTD = byte;
   1.123 +#else
   1.124 +	DDRD = (DDRD & 0xf0) | 0xf;
   1.125 +
   1.126 +	PORTD = (PORTD & 0xf0) | ((byte >> 4) & 0xf);
   1.127 +	PORTD = (PORTD & 0xf0) | (byte & 0xf);
   1.128 +#endif
   1.129 +}
   1.130 +
   1.131 +unsigned char lcd_read_byte(void)
   1.132 +{
   1.133 +#if LCD_BUS_WIDTH == 8
   1.134 +	DDRD = 0;
   1.135 +	PORTD = 0;	/* disable pull-ups */
   1.136 +
   1.137 +	return PIND;
   1.138 +#else
   1.139 +	unsigned char byte;
   1.140 +
   1.141 +	DDRD = DDRD & 0xf0;
   1.142 +	PORTD &= 0xf0;	/* disable pull-ups */
   1.143 +
   1.144 +	byte = (PIND & 0xf) << 4;
   1.145 +	return byte | (PIND & 0xf);
   1.146 +#endif
   1.147 +}
   1.148 +
   1.149 +void lcd_init(void)
   1.150 +{
   1.151 +	/* make sure the display has time to boot up */
   1.152 +	_delay_ms(20);
   1.153 +
   1.154 +	clear_bit(BIT_RW);
   1.155 +
   1.156 +	clear_bit(BIT_E);
   1.157 +	clear_bit(BIT_RS);
   1.158 +#if LCD_BUS_WIDTH == 8
   1.159 +	lcd_write_byte(CMD_FUNC | FUNC_BUS_8BIT | FUNC_LINES_2 | FUNC_FONT_5x8);
   1.160 +#else
   1.161 +	lcd_write_byte(CMD_FUNC | FUNC_BUS_4BIT | FUNC_LINES_2 | FUNC_FONT_5x8);
   1.162 +#endif
   1.163 +	enable();
   1.164 +	lcd_wait_busy();
   1.165 +
   1.166 +	clear_bit(BIT_RS);
   1.167 +	lcd_write_byte(CMD_ONOFF | ONOFF_DISP);
   1.168 +	enable();
   1.169 +	lcd_wait_busy();
   1.170 +
   1.171 +	clear_bit(BIT_RS);
   1.172 +	lcd_write_byte(CMD_ENTRY_MODE | (1 << 1));
   1.173 +	enable();
   1.174 +	lcd_wait_busy();
   1.175 +}
   1.176 +
   1.177 +void lcd_clear(void)
   1.178 +{
   1.179 +	clear_bit(BIT_RW);
   1.180 +
   1.181 +	clear_bit(BIT_E);
   1.182 +	clear_bit(BIT_RS);
   1.183 +	lcd_write_byte(CMD_CLEAR);
   1.184 +	enable();
   1.185 +	lcd_wait_busy();
   1.186 +}
   1.187 +
   1.188 +void lcd_set_cursor_addr(unsigned int addr)
   1.189 +{
   1.190 +	clear_bit(BIT_RW);
   1.191 +
   1.192 +	clear_bit(BIT_E);
   1.193 +	clear_bit(BIT_RS);
   1.194 +	lcd_write_byte(CMD_DDRAM_ADDR | addr);
   1.195 +	enable();
   1.196 +	lcd_wait_busy();
   1.197 +}
   1.198 +
   1.199 +void lcd_putchar(char c)
   1.200 +{
   1.201 +	clear_bit(BIT_RW);
   1.202 +
   1.203 +	set_bit(BIT_RS);
   1.204 +	lcd_write_byte(c);
   1.205 +	enable();
   1.206 +	lcd_wait_busy();
   1.207 +}
   1.208 +
   1.209 +void lcd_putstr(const char *str)
   1.210 +{
   1.211 +	while(*str) {
   1.212 +		lcd_putchar(*str++);
   1.213 +	}
   1.214 +}
   1.215 +
   1.216 +int lcd_stream_write(char c, FILE *fp)
   1.217 +{
   1.218 +	/* TODO terminal shit handling */
   1.219 +	lcd_putchar(c);
   1.220 +	return 0;
   1.221 +}
   1.222 +
   1.223 +void lcd_wait_busy(void)
   1.224 +{
   1.225 +	unsigned char data;
   1.226 +
   1.227 +	do {
   1.228 +		NSDELAY();
   1.229 +		clear_bit(BIT_E);
   1.230 +		clear_bit(BIT_RS);
   1.231 +		set_bit(BIT_RW);
   1.232 +		/*PIND = 0xff;*/
   1.233 +
   1.234 +		NSDELAY();
   1.235 +		set_bit(BIT_E);
   1.236 +		NSDELAY();
   1.237 +		data = lcd_read_byte();
   1.238 +		clear_bit(BIT_E);
   1.239 +		clear_bit(BIT_RW);
   1.240 +
   1.241 +	} while(data & (1 << 7));
   1.242 +}
   1.243 +
   1.244 +static void enable(void)
   1.245 +{
   1.246 +	NSDELAY();
   1.247 +	set_bit(BIT_E);
   1.248 +	NSDELAY();
   1.249 +	clear_bit(BIT_E);
   1.250 +	NSDELAY();
   1.251 +}
   1.252 +
   1.253 +static void set_bit(int bit)
   1.254 +{
   1.255 +	PORTC |= 1 << bit;
   1.256 +}
   1.257 +
   1.258 +static void clear_bit(int bit)
   1.259 +{
   1.260 +	PORTC &= ~(1 << bit);
   1.261 +}
   1.262 +
   1.263 +
   1.264 +void delay(int x)
   1.265 +{
   1.266 +	int i, j;
   1.267 +
   1.268 +	while(x-- > 0) {
   1.269 +		for(i=0; i<90; i++) {
   1.270 +			for(j=0; j<6; j++) {
   1.271 +				asm volatile("nop");
   1.272 +			}
   1.273 +		}
   1.274 +	}
   1.275 +}