blmc/i2c-slave.c

/***************************************************************************
 *   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"
#include "eeprom.h"

extern struct blmc_ blmc;
extern struct ee_param params;

/* SLA+R */
#define CMD_WAIT		0x00
#define CMD_READ_VERSION	0x01
#define CMD_READ_MEMORY		0x02
/* internal mappings */
#define CMD_READ_CHIPINFO	(0x10 | CMD_READ_MEMORY)
#define CMD_READ_FLASH		(0x20 | CMD_READ_MEMORY)
#define CMD_READ_EEPROM		(0x30 | CMD_READ_MEMORY)
#define CMD_READ_PARAMETERS	(0x40 | CMD_READ_MEMORY)	/* only in APP */

/* SLA+W */
#define CMD_SWITCH_APPLICATION	CMD_READ_VERSION
#define CMD_WRITE_MEMORY	CMD_READ_MEMORY
/* internal mappings */
#define CMD_BOOT_BOOTLOADER	(0x10 | CMD_SWITCH_APPLICATION)	/* only in APP */
#define CMD_BOOT_APPLICATION	(0x20 | CMD_SWITCH_APPLICATION)
#define CMD_WRITE_CHIPINFO	(0x10 | CMD_WRITE_MEMORY)	/* invalid */
#define CMD_WRITE_FLASH		(0x20 | CMD_WRITE_MEMORY)
#define CMD_WRITE_EEPROM	(0x30 | CMD_WRITE_MEMORY)
#define CMD_WRITE_PARAMETERS	(0x40 | CMD_WRITE_MEMORY)	/* only in APP */

/* CMD_SWITCH_APPLICATION parameter */
#define BOOTTYPE_BOOTLOADER	0x00				/* only in APP */
#define BOOTTYPE_APPLICATION	0x80

/* CMD_{READ|WRITE}_* parameter */
#define MEMTYPE_CHIPINFO	0x00
#define MEMTYPE_FLASH		0x01
#define MEMTYPE_EEPROM		0x02
#define MEMTYPE_PARAMETERS	0x03				/* only in APP */




const static uint8_t info[16] = "blmc m8-v1.2   ";

ISR(TWI_vect)
{
	static uint8_t cmd;
	static uint8_t bcnt;
	uint8_t data;
	uint8_t ack = (1<<TWEA);

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

	/* prev. SLA + W, data received, ACK returned -> receive Data and ACK */
	case 0x80:
		data = TWDR;
		switch (bcnt) {
		case 0:
			switch (data) {
			case CMD_SWITCH_APPLICATION:
			case CMD_WRITE_MEMORY:
				cmd = data;
				bcnt++;
				break;

			default:
				blmc.flags |= FLAG_I2C_ACTIVE;
				setpwm(data);
				cmd = CMD_WAIT;
				bcnt = 0;
				break;
			}
			break;

		case 1:
			switch (cmd) {
			case CMD_SWITCH_APPLICATION:
				if (data == BOOTTYPE_BOOTLOADER) {
					wdt_enable(WDTO_15MS);

				} else {
					ack = (0<<TWEA);
				}
				break;

			case CMD_WRITE_MEMORY:
				bcnt++;
				if (data == MEMTYPE_PARAMETERS) {
					cmd = CMD_WRITE_PARAMETERS;

				} else {
					ack = (0<<TWEA);
				}
				break;

			default:
				ack = (0<<TWEA);
				break;
			}
			break;

		case 2:	/* ignore address bytes */
		case 3:
			bcnt++;
			break;

		default:
			switch (cmd) {
			case CMD_WRITE_PARAMETERS:
				((uint8_t *)&params)[bcnt++ -4] = data;
				if (bcnt == sizeof(params)) {
					write_parameters();
					ack = (0<<TWEA);
				}
				break;

			default:
				ack = (0<<TWEA);
				break;
			}
			break;
		}

		if (ack == 0x00)
			bcnt = 0;

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

	/* SLA+R received, ACK returned -> send data */
	case 0xA8:
		bcnt = 0;
	/* prev. SLA+R, data sent, ACK returned -> send data */
	case 0xB8:
		switch (cmd) {
		case CMD_WAIT:
			switch (bcnt++) {
			case 0:
				data = blmc.current & 0xFF;
				break;

			case 1:
				data = 0xFF - blmc.pwm_limit;
				break;

			default:
				data = 0xFF;
				break;
			}
			break;

		case CMD_READ_VERSION:
			data = info[bcnt++];
			bcnt %= sizeof(info);
			break;

		case CMD_READ_PARAMETERS:
			data = ((uint8_t *)&params)[bcnt++];
			if (bcnt > sizeof(params))
				bcnt = 0;
			break;

		default:
			data = 0xFF;
			break;
		}

		TWDR = data;
		TWCR |= (1<<TWINT) | (1<<TWEA);
		break;

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

	/* failsave -> reset Hardware */
	default:
		TWCR |= (1<<TWINT) | (1<<TWSTO) | (1<<TWEA);
		break;
	}
}