ds3231-sensor.c

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/*
 * Copyright (c) 2012, Timothy Rule <trule.github@nym.hush.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/**
 * @file
 *              Sensors for DS3231 (RTC with Temperature Sensor).
 * @author
 *              Timothy Rule <trule.github@nym.hush.com>
 * @note
 *              See http://www.maxim-ic.com/datasheet/index.mvp/id/4627
 */

#include "ds3231-sensor.h"
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <contiki.h>
#include "i2c.h"
#include <inttypes.h>

//#define DEBUG
#ifdef DEBUG
#define dprintf(FORMAT, args...) printf(FORMAT, ##args)
#else
#define dprintf(...)
#endif

/**
 * DS3231 is connected to TWI Master on Port C (Pins 0 & 1). The active low
 * Interrupt from the DS3231 is connected in Pin 2 of Port C.
 */
//#define I2C(a,b,c,d)  twi_transaction(&TWIC, DS3231_ADDR, (a), (b), (c), (d));

int I2C(uint8_t* write,uint16_t write_len,uint8_t* read,uint16_t read_len)
{
    // This gets disabled (not be us) sometimes
    i2c_master_enable();

    uint8_t write_res = I2C_MASTER_ERR_NONE;
    uint8_t read_res = I2C_MASTER_ERR_NONE;

        if (write_len) {
        write_res = i2c_burst_send(DS3231_ADDR, write, write_len);
        }

        if (read_len) {
        read_res = i2c_burst_receive(DS3231_ADDR, read, read_len);
        }

    i2c_master_disable();

    // 0 for success
        return !(write_res == I2C_MASTER_ERR_NONE && read_res == I2C_MASTER_ERR_NONE);
}

/* Define the sensor object. */
const struct sensors_sensor ds3231_sensor;

/* Sensor status. */
enum {
        ON,
        OFF
};
static uint8_t state = OFF;

/**
 * ds3231_get_time
 *
 * @return      0 for success, I2C error code otherwise.
 *
 * @note        The base date of tm struct is 1900-01-01 and the base date stored
 *                      in the RTC for this application is 2000-01-01. An adjustment of
 *                      100 is made before getting the time.
 */
int ds3231_get_time(struct tm *t) {
    int rc;
        ds_3231_time_t time;

        memset(time.data, 0, 8);

        /* Read the time from the DS3231. */
        time.tm.address = 0;
    rc = I2C(time.data, 1, &time.data[1], 7);
        if (rc != 0) {
                return rc;
        }

        /* Convert to tm struct */
        t->tm_year = time.tm.year + time.tm.dyear * 10 + 100;
    // Month field should be 0 indexed.
        t->tm_mon = time.tm.mon + time.tm.dmon * 10 -1;
        t->tm_mday = time.tm.date + time.tm.ddate * 10;
        t->tm_hour = time.tm.hour + time.tm.dhour * 10;
        t->tm_min = time.tm.min + time.tm.dmin * 10;
        t->tm_sec = time.tm.sec + time.tm.dsec * 10;

        dprintf("years %d, months %d, days %d, hours %d, minutes %d, seconds %d\n", t->tm_year, t->tm_mon, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec);

    return 0;
}

/**
 * ds3231_set_time
 *
 * @return      0 for success, I2C error code otherwise.
 *
 * @note        The base date of tm struct is 1900-01-01 and the base date stored
 *                      in the RTC for this application is 2000-01-01. An adjustment of
 *                      100 is made before setting the time.
 */
int ds3231_set_time(struct tm *t) {
        int rc;
        ds_3231_time_t time;

        memset(time.data, 0, 8);

        /* Convert the tm struct to the register representation of the DS3231. */
        time.tm.dyear = (t->tm_year - 100) / 10;
        time.tm.year = (t->tm_year - 100) % 10;
    // Months in struct tm are 0 indexed
        time.tm.dmon = (t->tm_mon + 1) / 10;
        time.tm.mon = (t->tm_mon + 1) % 10;
        time.tm.ddate = t->tm_mday / 10;
        time.tm.date = t->tm_mday % 10;
        time.tm.day = 1; /* Not used, set to 1. */
        time.tm.dhour = t->tm_hour / 10;
        time.tm.hour = t->tm_hour % 10;
        time.tm.dmin = t->tm_min / 10;
        time.tm.min = t->tm_min % 10;
        time.tm.dsec = t->tm_sec / 10;
        time.tm.sec = t->tm_sec % 10;

        dprintf("year %d%d, months %d%d, days %d%d, hours %d%d, minutes %d%d, seconds %d%d\n", time.tm.dyear, time.tm.year, time.tm.dmon, time.tm.mon, time.tm.ddate, time.tm.date, time.tm.dhour, time.tm.hour, time.tm.dmin, time.tm.min, time.tm.dsec, time.tm.sec);
        /* Send the new time to the DS3231. */
        rc = I2C(time.data, 8, NULL, 0);
        if (rc != 0) {
                return rc;
        }

        return 0;
}

/**
 * ds3231_set_alarm
 *
 * Sets the first alarm of the DS3231. Alarm Mask Bits A1M1-4 are all set
 * to 0 which means the alarm will fire on the complete alarm setting (date,
 * hour, minute & second).
 *
 * When the alarm is triggered the INT pin of the DS3231 will be pulled low.
 * This pin is connected to Port C Pin 2 of the AVR XMega.
 *
 * @return      0 for success, I2C error code otherwise.
 */
int ds3231_set_alarm(struct tm *t)
{
        int rc;
        ds_3231_alarm_t alarm;
        uint8_t regs[3];

        memset(alarm.data, 0, 5);

        /* Set the Alarm 1 registers. */
        alarm.tm.address = 7; /* DS3231 register 7, start of Alarm 1. */
        alarm.tm.ddate = t->tm_mday / 10;
        alarm.tm.date = t->tm_mday % 10;
        alarm.tm.dhour = t->tm_hour / 10;
        alarm.tm.hour = t->tm_hour % 10;
        alarm.tm.dmin = t->tm_min / 10;
        alarm.tm.min = t->tm_min % 10;
        alarm.tm.dsec = t->tm_sec / 10;
        alarm.tm.sec = t->tm_sec % 10;

        /* Send the Alarm to the DS3231. */
        rc = I2C(alarm.data, 5, NULL, 0);
        if (rc != 0) {
                return rc;
        }

        /* Read in Control and Status registers. */
        regs[0] = 0x0e;
        rc = I2C(&regs[0], 1, &regs[1], 2);
        if (rc != 0) {
                return rc;
        }

        /* Enable Alarm 1, then write the Control and Status registers. */
        regs[1] |= DS3231_CONTROL_A1IE_SET_MASK;
        regs[2] &= DS3231_STATUS_A1F_CLEAR_MASK;
        rc = I2C(regs, 3, NULL, 0);
        if (rc != 0) {
                return rc;
        }

        return 0;
}

/**
 * ds3231_clear_alarm
 *
 * Clears and disables Alarm 1.
 *
 * @return      0 for success, I2C error code otherwise.
 */
int ds3231_clear_alarm(void)
{
        int rc;
        uint8_t regs[3];

        /* Read in Control and Status registers. */
        regs[0] = 0x0e;
        rc = I2C(&regs[0], 1, &regs[1], 2);
        if (rc != 0) {
                return rc;
        }

        /* Write the Control and Status registers. */
        regs[1] &= DS3231_CONTROL_A1IE_CLEAR_MASK;
        regs[2] &= DS3231_STATUS_A1F_CLEAR_MASK;
        rc = I2C(regs, 3, NULL, 0);
        if (rc != 0) {
                return rc;
        }

        return 0;
}

/**
 * ds3231_temperature
 *
 * Register 11h: bit 7 is sign, bit 6-0 are temperature.
 * Register 12h: bit 7 & 6 are decimal point (0.25 * xxb).
 *
 * @return      Temperature * 100 (centi %) however accuracy is limited to
 *              0.25 degree increments.
 */
int ds3231_get_temperature(int *temperature)
{
        int rc;
        uint8_t addr_set[6] = { 0x11 };
        uint8_t temp_regs[21];

        rc = I2C(addr_set, 1, temp_regs, 2);
        if (rc != 0) {
                return rc;
        }

        *temperature = ((temp_regs[0]) & 0x7f) * 100; /* Temperature in cC. */
        *temperature += ((temp_regs[1] & 0xc0) >> 6) * 25; /* .25 .. .75 */
        if (temp_regs[0] & 0x80)
                *temperature *= -1;

        dprintf("Temperature is %d\n", *temperature);

        return 0;
}

/**
 * configure
 */
int configure(int type, int c)
{
        int rc = 0;

        switch (type) {
        case DS3231_CONFIG_SET_TIME:
                /* The address of a tm structure is pass via variable
                 * 'c' which works because sizeof(tm*) and sizeof(int)
                 * are the same on AVR XMEGA. Its generally not a good
                 * thing to do ... things like that. */
                return ds3231_set_time((struct tm*) c);
        case DS3231_CONFIG_SET_ALARM:
                return ds3231_set_alarm((struct tm*) c);
        case DS3231_CONFIG_CLEAR_ALARM:
                return ds3231_clear_alarm();
        case SENSORS_ACTIVE:
                if (c) {
                        state = OFF;
                        dprintf("DS3231 Sensor Configure ...\n");
                        rc = ds3231_clear_alarm();
                        if (rc == 0)
                                state = ON;
                        break;
                }
        default:
                state = OFF;
        }

        return 0;
}

/**
 * status
 */
int status(int type)
{
        switch (type) {
        case SENSORS_ACTIVE:
        case SENSORS_READY:
                return (state == ON);
        default:
                return 0;
        }
}

/* Initialise the sensor object and make it available to Contiki OS. */
SENSORS_SENSOR(ds3231_sensor, "ds3231", NULL, configure, status);