/***************************************************************************
 *   Copyright (C) 09/2007 by Olaf Rempel                                  *
 *   razzor@kopf-tisch.de                                                  *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; version 2 of the License,               *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/wdt.h>

#include "main.h"
#include "blmc.h"

extern struct blmc_ blmc;

#define CMD_NONE	0x00
#define CMD_SETPWM	0x10
#define CMD_GETSTAT	0x20
#define CMD_REBOOT	0x80

ISR(TWI_vect)
{
	static uint8_t cmd = CMD_NONE;

	switch (TWSR & 0xF8) {
	/* SLA + W received, ACK returned -> receive Data and ACK */
	case 0x60:
		cmd = CMD_NONE;
		TWCR |= (1<<TWINT) | (1<<TWEA);
		break;

	/* prev. SLA + W, data received, ACK returned -> receive Data and ACK */
	case 0x80:
		switch (cmd & 0xF0) {
		/* First bytes -> Command */
		case CMD_NONE:
			cmd = TWDR;
			break;

		/* set pwm */
		case CMD_SETPWM:
			setpwm(TWDR);
			cmd = CMD_NONE;
			break;

		/* set parameters */
		case CMD_REBOOT:
			if (TWDR == 0x42)
				wdt_enable(WDTO_15MS);
			cmd = CMD_NONE;
			break;

		/* rest invalid */
		default:
			cmd = CMD_NONE;
			break;
		}

		TWCR |= (1<<TWINT);
		break;

	/* SLA+R received, ACK returned -> send data */
	case 0xA8:
	/* prev. SLA+R, data sent, ACK returned -> send data */
	case 0xB8:
		switch (cmd & 0xF0) {
		/* get Current */
		case CMD_GETSTAT:
			switch (cmd++ & 0x0F) {
			case 0:	TWDR = blmc.pwm - blmc.pwm_limit;
				break;

			case 1:	TWDR = blmc.pwm;
				break;

			case 2:	TWDR = (blmc.rpm >> 8);
				break;

			case 3: TWDR = (blmc.rpm & 0xFF);
				break;

			case 4:	TWDR = (blmc.current >> 8);
				break;

			case 5: TWDR = (blmc.current & 0xFF);
				break;

			case 6:	TWDR = (blmc.voltage >> 8);
				break;

			case 7: TWDR = (blmc.voltage & 0xFF);
				cmd = CMD_NONE;
				break;
			}
			break;

		/* rest invalid */
		default:
			cmd = CMD_NONE;
			break;
		}

		TWCR |= (1<<TWINT);
		break;

	/* STOP or repeated START */
	case 0xA0:
	/* Data transmitted, NACK returned */
	case 0xC0:
		TWCR |= (1<<TWINT) | (1<<TWEA);
		break;

	/* Illegal state -> reset Hardware */
	case 0xF8:
		TWCR |= (1<<TWINT) | (1<<TWSTO) | (1<<TWEA);
		break;
	}
}