#include <avr/io.h>
#include <util/delay.h>

#include "bridge.h"

/* port D
 *
 *  4 1- (NMOS, inverted) 
 *  5 1+ (PMOS)
 *  6 2- (NMOS, inverted)
 *  7 2+ (PMOS)
 *
 */

#define D_1_MINUS	(1 << 4)
#define D_1_PLUS	(1 << 5)
#define D_2_MINUS	(1 << 6)
#define D_2_PLUS	(1 << 7)

enum bridge_state {
	BRIDGE_OFF,
	BRIDGE_HEATING,
	BRIDGE_COOLING
};

static enum bridge_state bridge_state;

/* Turns the H-bridge off, putting the output
 * into high impedance mode. */
void bridge_off(void)
{
	if (bridge_state == BRIDGE_OFF)
		return;

	PORTD |= D_1_MINUS | D_2_MINUS;
	PORTD &= ~(D_1_PLUS | D_2_PLUS);
	_delay_ms(100);
	bridge_state = BRIDGE_OFF;
}

/* Turns the H-bridge on, setting 1+ 2- */
void bridge_on_heat(void)
{
	if (bridge_state == BRIDGE_HEATING)
		return;

	bridge_off();
	bridge_state = BRIDGE_HEATING;
	PORTD |= D_1_PLUS;
	PORTD &= ~D_2_MINUS;
}

/* Turns the H-bridge on, setting 1- 2+ */
void bridge_on_cool(void)
{
	if (bridge_state == BRIDGE_COOLING)
		return;

	bridge_off();
	bridge_state = BRIDGE_COOLING;
	PORTD |= D_2_PLUS;
	PORTD &= ~D_1_MINUS;
}

/* Initializes the output port needed for the H-bridge */
void bridge_init(void)
{
	PORTD |= D_1_MINUS | D_2_MINUS;
	PORTD &= ~(D_1_PLUS | D_2_PLUS);
	DDRD |= D_1_PLUS | D_1_MINUS | D_2_PLUS | D_2_MINUS;
	bridge_state = BRIDGE_OFF;
}