1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/Makefile	Sun Jan 27 10:11:40 2013 +0200
     1.3 @@ -0,0 +1,34 @@
     1.4 +src = $(wildcard *.c)
     1.5 +obj = $(src:.c=.o)
     1.6 +bin = voltmeter
     1.7 +hex = $(bin).hex
     1.8 +eep = $(bin).eep
     1.9 +
    1.10 +mcu_gcc = atmega168
    1.11 +mcu_dude = m168
    1.12 +
    1.13 +CC = avr-gcc
    1.14 +OBJCOPY = avr-objcopy
    1.15 +
    1.16 +CFLAGS = -O2 -pedantic -Wall -mmcu=$(mcu_gcc)
    1.17 +LDFLAGS = -Wl,-Map,$(bin).map -mmcu=$(mcu_gcc) -Wl,-u,vfprintf -lprintf_flt -lm
    1.18 +
    1.19 +.PHONY: all
    1.20 +all: $(hex) $(eep)
    1.21 +
    1.22 +$(bin): $(obj)
    1.23 +	$(CC) -o $@ $(obj) $(LDFLAGS)
    1.24 +
    1.25 +$(hex): $(bin)
    1.26 +	$(OBJCOPY) -j .text -j .data -O ihex -R .eeprom $< $@
    1.27 +
    1.28 +$(eep): $(bin)
    1.29 +	$(OBJCOPY) -j .eeprom --change-section-lma .eeprom=0 -O ihex $< $@
    1.30 +
    1.31 +.PHONY: program
    1.32 +program: $(hex)
    1.33 +	avrdude -c usbtiny -p $(mcu_dude) -e -U flash:w:$(hex)
    1.34 +
    1.35 +.PHONY: clean
    1.36 +clean:
    1.37 +	rm -f $(bin) $(obj) $(hex) $(eep) $(bin).map

     2.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     2.2 +++ b/voltmeter.c	Sun Jan 27 10:11:40 2013 +0200
     2.3 @@ -0,0 +1,252 @@
     2.4 +#define F_CLK	1000000
     2.5 +#define F_CPU	1000000
     2.6 +
     2.7 +#include <stdio.h>
     2.8 +#include <avr/io.h>
     2.9 +#include <util/delay.h>
    2.10 +
    2.11 +/* hardware setup
    2.12 + * - PORT D: data bits
    2.13 + * - PORT C
    2.14 + *     bit 0: RS
    2.15 + *     bit 1: R/W
    2.16 + *     bit 2: E
    2.17 + */
    2.18 +
    2.19 +#define BIT_RS	3
    2.20 +#define BIT_RW	4
    2.21 +#define BIT_E	5
    2.22 +
    2.23 +#define CMD_CLEAR		1
    2.24 +#define CMD_RET			(1 << 1)
    2.25 +#define CMD_ENTRY_MODE	(1 << 2)
    2.26 +#define CMD_ONOFF		(1 << 3)
    2.27 +#define CMD_SHIFT		(1 << 4)
    2.28 +#define CMD_FUNC		(1 << 5)
    2.29 +#define CMD_CGRAM_ADDR	(1 << 6)
    2.30 +#define CMD_DDRAM_ADDR	(1 << 7)
    2.31 +
    2.32 +#define FUNC_BUS_4BIT	0
    2.33 +#define FUNC_BUS_8BIT	(1 << 4)
    2.34 +#define FUNC_LINES_1	0
    2.35 +#define FUNC_LINES_2	(1 << 3)
    2.36 +#define FUNC_FONT_5x8	0
    2.37 +#define FUNC_FONT_5x11	(1 << 2)
    2.38 +
    2.39 +#define ONOFF_DISP			(1 << 2)
    2.40 +#define ONOFF_CURSOR		(1 << 1)
    2.41 +#define ONOFF_CURSOR_POS	1
    2.42 +
    2.43 +void setup_adc(void);
    2.44 +long read_adc(void);
    2.45 +
    2.46 +void lcd_init(void);
    2.47 +void lcd_clear(void);
    2.48 +void lcd_set_cursor_addr(unsigned int addr);
    2.49 +void lcd_putchar(char c);
    2.50 +void lcd_putstr(const char *str);
    2.51 +int lcd_stream_write(char c, FILE *fp);
    2.52 +void lcd_wait_busy(void);
    2.53 +static void enable(void);
    2.54 +static void set_bit(int bit);
    2.55 +static void clear_bit(int bit);
    2.56 +void delay(int x);
    2.57 +
    2.58 +#define NSDELAY()	asm volatile ("nop")
    2.59 +#define DEBUG(i)	(PORTB = (1 << (i)))
    2.60 +
    2.61 +FILE stream_lcd = FDEV_SETUP_STREAM(lcd_stream_write, NULL, _FDEV_SETUP_WRITE);
    2.62 +
    2.63 +int main(void)
    2.64 +{
    2.65 +	stdout = stderr = &stream_lcd;
    2.66 +
    2.67 +	DDRC = 0xfe;
    2.68 +	PORTC = 0;	/* disable pullups */
    2.69 +
    2.70 +	lcd_init();
    2.71 +	lcd_clear();
    2.72 +
    2.73 +	printf("initializing...");
    2.74 +	setup_adc();
    2.75 +
    2.76 +	for(;;) {
    2.77 +		long val = read_adc();
    2.78 +		double ref = 1.08 * 1.47 / 0.47;
    2.79 +		double voltage = ref * (double)val / (double)1024;
    2.80 +		lcd_clear();
    2.81 +
    2.82 +		if(val == 1023) {
    2.83 +			printf("*** RANGE ***   ");
    2.84 +		} else {
    2.85 +			printf("%.2f volts      ", voltage);
    2.86 +		}
    2.87 +		_delay_ms(500);
    2.88 +	}
    2.89 +	return 0;
    2.90 +}
    2.91 +
    2.92 +void setup_adc(void)
    2.93 +{
    2.94 +	/* disable digital input buffer on ADC0 pin */
    2.95 +	DIDR0 = 1;
    2.96 +
    2.97 +	/* use the internal bandgap as a reference */
    2.98 +	ADMUX = 3 << REFS0;
    2.99 +
   2.100 +	/* - enable ADC
   2.101 +	 * - set ADC clock prescaler to clock / 8
   2.102 +	 */
   2.103 +	ADCSRA = (1 << ADEN) | (3 << ADPS0);
   2.104 +}
   2.105 +
   2.106 +long read_adc(void)
   2.107 +{
   2.108 +	long low;
   2.109 +
   2.110 +	/* start conversion */
   2.111 +	ADCSRA |= (1 << ADSC);
   2.112 +
   2.113 +	/* wait while converting */
   2.114 +	while(ADCSRA & (1 << ADSC));
   2.115 +
   2.116 +	low = ADCL;
   2.117 +	return low | ((long)ADCH << 8);
   2.118 +}
   2.119 +
   2.120 +void lcd_init(void)
   2.121 +{
   2.122 +	DDRD = 0x0f;	/* port d[0, 3] -> output */
   2.123 +
   2.124 +	/* make sure the display has time to boot up */
   2.125 +	_delay_ms(20);
   2.126 +
   2.127 +	clear_bit(BIT_RW);
   2.128 +
   2.129 +	clear_bit(BIT_E);
   2.130 +	clear_bit(BIT_RS);
   2.131 +	PORTD = CMD_FUNC | FUNC_BUS_8BIT | FUNC_LINES_2 | FUNC_FONT_5x8;
   2.132 +	enable();
   2.133 +	lcd_wait_busy();
   2.134 +
   2.135 +	clear_bit(BIT_RS);
   2.136 +	PORTD = CMD_ONOFF | ONOFF_DISP | ONOFF_CURSOR;
   2.137 +	enable();
   2.138 +	lcd_wait_busy();
   2.139 +
   2.140 +	clear_bit(BIT_RS);
   2.141 +	PORTD = CMD_ENTRY_MODE | (1 << 1);
   2.142 +	enable();
   2.143 +	lcd_wait_busy();
   2.144 +}
   2.145 +
   2.146 +void lcd_clear(void)
   2.147 +{
   2.148 +	DDRD = 0xff;	/* port d -> output */
   2.149 +
   2.150 +	clear_bit(BIT_RW);
   2.151 +
   2.152 +	clear_bit(BIT_E);
   2.153 +	clear_bit(BIT_RS);
   2.154 +	PORTD = CMD_CLEAR;
   2.155 +	enable();
   2.156 +	lcd_wait_busy();
   2.157 +}
   2.158 +
   2.159 +void lcd_set_cursor_addr(unsigned int addr)
   2.160 +{
   2.161 +	DDRD = 0xff;	/* port d -> output */
   2.162 +
   2.163 +	clear_bit(BIT_RW);
   2.164 +
   2.165 +	clear_bit(BIT_E);
   2.166 +	clear_bit(BIT_RS);
   2.167 +	PORTD = CMD_DDRAM_ADDR | addr;
   2.168 +	enable();
   2.169 +	lcd_wait_busy();
   2.170 +}
   2.171 +
   2.172 +void lcd_putchar(char c)
   2.173 +{
   2.174 +	DDRD = 0xff;	/* port d -> output */
   2.175 +
   2.176 +	clear_bit(BIT_RW);
   2.177 +
   2.178 +	set_bit(BIT_RS);
   2.179 +	PORTD = c;
   2.180 +	enable();
   2.181 +	lcd_wait_busy();
   2.182 +}
   2.183 +
   2.184 +void lcd_putstr(const char *str)
   2.185 +{
   2.186 +	while(*str) {
   2.187 +		lcd_putchar(*str++);
   2.188 +	}
   2.189 +}
   2.190 +
   2.191 +int lcd_stream_write(char c, FILE *fp)
   2.192 +{
   2.193 +	/* TODO terminal shit handling */
   2.194 +	lcd_putchar(c);
   2.195 +	return 0;
   2.196 +}
   2.197 +
   2.198 +void lcd_wait_busy(void)
   2.199 +{
   2.200 +	unsigned char data;
   2.201 +
   2.202 +	DDRD = 0;		/* port d -> input */
   2.203 +	PORTD = 0;		/* disable pull-ups */
   2.204 +
   2.205 +	do {
   2.206 +		NSDELAY();
   2.207 +		clear_bit(BIT_E);
   2.208 +		clear_bit(BIT_RS);
   2.209 +		set_bit(BIT_RW);
   2.210 +		/*PIND = 0xff;*/
   2.211 +
   2.212 +		NSDELAY();
   2.213 +		set_bit(BIT_E);
   2.214 +		NSDELAY();
   2.215 +		data = PIND;
   2.216 +		clear_bit(BIT_E);
   2.217 +		clear_bit(BIT_RW);
   2.218 +
   2.219 +	} while(data & (1 << 7));
   2.220 +
   2.221 +	DDRD = 0xff;	/* port d -> output */
   2.222 +}
   2.223 +
   2.224 +static void enable(void)
   2.225 +{
   2.226 +	NSDELAY();
   2.227 +	set_bit(BIT_E);
   2.228 +	NSDELAY();
   2.229 +	clear_bit(BIT_E);
   2.230 +	NSDELAY();
   2.231 +}
   2.232 +
   2.233 +static void set_bit(int bit)
   2.234 +{
   2.235 +	PORTC |= 1 << bit;
   2.236 +}
   2.237 +
   2.238 +static void clear_bit(int bit)
   2.239 +{
   2.240 +	PORTC &= ~(1 << bit);
   2.241 +}
   2.242 +
   2.243 +
   2.244 +void delay(int x)
   2.245 +{
   2.246 +	int i, j;
   2.247 +
   2.248 +	while(x-- > 0) {
   2.249 +		for(i=0; i<90; i++) {
   2.250 +			for(j=0; j<6; j++) {
   2.251 +				asm volatile("nop");
   2.252 +			}
   2.253 +		}
   2.254 +	}
   2.255 +}