nuclear@0: /* PORT USAGE
nuclear@0:  *
nuclear@0:  * D0-D3: data bus, connected to the D0-D3 pins of all the 4511 chips
nuclear@0:  * C0-C5,D4,D5: directly driving the 8 speed graph LEDs
nuclear@0:  * B0-B2: connected to the decoder controlling the 4511 latches as such:
nuclear@0:  *        000 - speed most significant
nuclear@0:  *        001 - speed least significant
nuclear@0:  *        010 - dist most significant
nuclear@0:  *        011 - dist middle
nuclear@0:  *        100 - dist least significant
nuclear@0:  *        101 - all latches are off (high)
nuclear@0:  * B3-B5: ISP. B4 also acts as generic pushbutton input
nuclear@0:  * B6,B7: XTAL
nuclear@0:  * D6,D7: comparator, hall effect sensor input and threshold trimpot.
nuclear@0:  */
nuclear@0: 
nuclear@0: /* 16mhz resonator */
nuclear@0: #define F_CPU	2000000
nuclear@0: 
nuclear@0: #include <avr/io.h>
nuclear@0: #include <avr/interrupt.h>
nuclear@0: #include <util/delay.h>
nuclear@0: 
nuclear@0: void latch(int n);
nuclear@0: void update_display(void);
nuclear@0: 
nuclear@0: int state;
nuclear@0: int debug_mode = 1;
nuclear@0: 
nuclear@0: unsigned long nrot;
nuclear@0: 
nuclear@0: /* wheel perimeter in centimeters */
nuclear@0: #define WHEEL_PERIMETER		100
nuclear@0: 
nuclear@0: int main(void)
nuclear@0: {
nuclear@0: 	int i;
nuclear@0: 
nuclear@0: 	DDRB = 0xf;		/* only first four bits are outputs */
nuclear@0: 	DDRC = 0xff;	/* speed leds 6 bits */
nuclear@0: 	DDRD = 0xff;	/* 4bits data bus, 2 bits speed leds, 2 bits comparator (don't care) */
nuclear@0: 
nuclear@0: 	/* zero-out the displays and disable all pullups except for the reset pin */
nuclear@0: 	PORTB = 0;
nuclear@0: 	PORTC = 0x40;	/* 6th bit set, C6 is reset */
nuclear@0: 	PORTD = 0;
nuclear@0: 
nuclear@0: 	for(i=0; i<5; i++) {
nuclear@0: 		latch(i);
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	/* read initial comparator state */
nuclear@0: 	state = (ACSR >> ACO) & 1;
nuclear@0: 
nuclear@0: 	if(debug_mode) {
nuclear@0: 		int i, j, leds, leds_val;
nuclear@0: 
nuclear@0: 		for(i=0; ; i++) {
nuclear@0: 			for(j=0; j<5; j++) {
nuclear@0: 				/* set bits */
nuclear@0: 				PORTD = (PORTD & 0xf0) | (((i + j) % 10) & 0xf);
nuclear@0: 				/* latch */
nuclear@0: 				latch(j);
nuclear@0: 			}
nuclear@0: 
nuclear@0: 			leds_val = 0;
nuclear@0: 			leds = i % 8;
nuclear@0: 			for(j=0; j<8; j++) {
nuclear@0: 				if(j <= leds) {
nuclear@0: 					leds_val |= (1 << j);
nuclear@0: 				}
nuclear@0: 			}
nuclear@0: 			PORTC = leds_val;
nuclear@0: 			PORTD = (PORTD & 0xf) | ((leds_val >> 2) & (3 << 4));
nuclear@0: 
nuclear@0: 			_delay_ms(1000);
nuclear@0: 		}
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	/* disable digital input buffer for the AINn pins */
nuclear@0: 	/*DIDR1 = 0;*/
nuclear@0: 
nuclear@0: 	ACSR = (1 << ACIE);
nuclear@0: 	/* in debug mode we want an interrupt both on rising and falling edge
nuclear@0: 	 * to be able to blink leds when the wheel goes past. otherwise we only need
nuclear@0: 	 * a rising edge interrupt to increment the rotation counter.
nuclear@0: 	 */
nuclear@0: 	if(!debug_mode) {
nuclear@0: 		/* rising edge interrupt */
nuclear@0: 		ACSR |= (3 << ACIS0);
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	sei();
nuclear@0: 
nuclear@0: 	for(;;);
nuclear@0: 	return 0;
nuclear@0: }
nuclear@0: 
nuclear@0: void latch(int n)
nuclear@0: {
nuclear@0: 	unsigned char upper = PORTB & 0xf0;
nuclear@0: 	/* pull latch low */
nuclear@0: 	PORTB = upper | n;
nuclear@0: 	asm volatile("nop");
nuclear@0: 	/* pull all latches high again */
nuclear@0: 	PORTB = upper | 5;
nuclear@0: }
nuclear@0: 
nuclear@0: ISR(ANALOG_COMP_vect)
nuclear@0: {
nuclear@0: 	if(debug_mode) {
nuclear@0: 		int state = (ACSR >> ACO) & 1;
nuclear@0: 
nuclear@0: 		if(state) {
nuclear@0: 			PORTB |= 1;
nuclear@0: 			nrot++;
nuclear@0: 		} else {
nuclear@0: 			PORTB &= ~1;
nuclear@0: 		}
nuclear@0: 	} else {
nuclear@0: 		nrot++;
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	update_display();
nuclear@0: }
nuclear@0: 
nuclear@0: void update_display(void)
nuclear@0: {
nuclear@0: 	unsigned long dist_cm = (nrot * WHEEL_PERIMETER);
nuclear@0: 
nuclear@0: 	/* TODO */
nuclear@0: }