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incubator-nuttx/drivers/timers/ds3231.c

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/****************************************************************************
* drivers/timers/ds3231.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdbool.h>
#include <time.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/arch.h>
#include <nuttx/i2c/i2c_master.h>
#include <nuttx/timers/ds3231.h>
#include "ds3231.h"
#ifdef CONFIG_RTC_DSXXXX
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Configuration ************************************************************/
/* This RTC implementation supports only date/time RTC hardware */
#ifndef CONFIG_RTC_DATETIME
# error CONFIG_RTC_DATETIME must be set to use this driver
#endif
#ifdef CONFIG_RTC_HIRES
# error CONFIG_RTC_HIRES must NOT be set with this driver
#endif
#ifndef CONFIG_DS3231_I2C_FREQUENCY
# error CONFIG_DS3231_I2C_FREQUENCY is not configured
# define CONFIG_DS3231_I2C_FREQUENCY 400000
#endif
#if CONFIG_DS3231_I2C_FREQUENCY > 400000
# error CONFIG_DS3231_I2C_FREQUENCY is out of range
#endif
#define DS3231_I2C_ADDRESS 0x68
/****************************************************************************
* Private Types
****************************************************************************/
/* This structure describes the state of the DS3231 chip.
* Only a single RTC is supported.
*/
struct ds3231_dev_s
{
FAR struct i2c_master_s *i2c; /* Contained reference to the I2C bus driver */
};
/****************************************************************************
* Public Data
****************************************************************************/
/* g_rtc_enabled is set true after the RTC has successfully initialized */
volatile bool g_rtc_enabled = false;
/****************************************************************************
* Private Data
****************************************************************************/
/* The state of the DS3231 chip. Only a single RTC is supported */
static struct ds3231_dev_s g_ds3231;
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: rtc_dumptime
*
* Description:
* Show the broken out time.
*
* Input Parameters:
* None
*
* Returned Value:
* None
*
****************************************************************************/
#ifdef CONFIG_DEBUG_RTC_INFO
static void rtc_dumptime(FAR struct tm *tp, FAR const char *msg)
{
rtcinfo("%s:\n", msg);
rtcinfo(" tm_sec: %08x\n", tp->tm_sec);
rtcinfo(" tm_min: %08x\n", tp->tm_min);
rtcinfo(" tm_hour: %08x\n", tp->tm_hour);
rtcinfo(" tm_mday: %08x\n", tp->tm_mday);
rtcinfo(" tm_mon: %08x\n", tp->tm_mon);
rtcinfo(" tm_year: %08x\n", tp->tm_year);
rtcinfo(" tm_wday: %08x\n", tp->tm_wday);
rtcinfo(" tm_yday: %08x\n", tp->tm_yday);
rtcinfo(" tm_isdst: %08x\n", tp->tm_isdst);
}
#else
# define rtc_dumptime(tp, msg)
#endif
/****************************************************************************
* Name: rtc_bin2bcd
*
* Description:
* Converts a 2 digit binary to BCD format
*
* Input Parameters:
* value - The byte to be converted.
*
* Returned Value:
* The value in BCD representation
*
****************************************************************************/
static uint8_t rtc_bin2bcd(int value)
{
uint8_t msbcd = 0;
while (value >= 10)
{
msbcd++;
value -= 10;
}
return (msbcd << 4) | value;
}
/****************************************************************************
* Name: rtc_bcd2bin
*
* Description:
* Convert from 2 digit BCD to binary.
*
* Input Parameters:
* value - The BCD value to be converted.
*
* Returned Value:
* The value in binary representation
*
****************************************************************************/
static int rtc_bcd2bin(uint8_t value)
{
int tens = ((int)value >> 4) * 10;
return tens + (value & 0x0f);
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: dsxxxx_rtc_initialize
*
* Description:
* Initialize the hardware RTC per the selected configuration.
* This function is called once during the OS initialization sequence by
* board-specific logic.
*
* After dsxxxx_rtc_initialize() is called, the OS function
* clock_synchronize() should also be called to synchronize the system
* timer to a hardware RTC. That operation is normally performed
* automatically by the system during clock initialization. However, when
* an external RTC is used, the board logic will need to explicitly
* re-synchronize the system timer to the RTC when the RTC becomes
* available.
*
* Input Parameters:
* None
*
* Returned Value:
* Zero (OK) on success; a negated errno on failure
*
****************************************************************************/
int dsxxxx_rtc_initialize(FAR struct i2c_master_s *i2c)
{
/* Remember the i2c device and claim that the RTC is enabled */
g_ds3231.i2c = i2c;
g_rtc_enabled = true;
return OK;
}
/****************************************************************************
* Name: up_rtc_getdatetime
*
* Description:
* Get the current date and time from the date/time RTC. This interface
* is only supported by the date/time RTC hardware implementation.
* It is used to replace the system timer. It is only used by the RTOS
* during initialization to set up the system time when CONFIG_RTC and
* CONFIG_RTC_DATETIME are selected (and CONFIG_RTC_HIRES is not).
*
* NOTE:
* Some date/time RTC hardware is capability of sub-second accuracy.
* That sub-second accuracy is lost in this interface. However, since the
* system time is reinitialized on each power-up/reset, there will be no
* timing inaccuracy in the long run.
*
* Input Parameters:
* tp - The location to return the high resolution time value.
*
* Returned Value:
* Zero (OK) on success; a negated errno on failure
*
****************************************************************************/
int up_rtc_getdatetime(FAR struct tm *tp)
{
struct i2c_msg_s msg[4];
uint8_t secaddr;
uint8_t buffer[7];
uint8_t seconds;
int tmp;
int ret;
/* If this function is called before the RTC has been initialized
* (and it will be), then just return the data/time of the epoch,
* 12:00 am, Jan 1, 1970.
*/
if (!g_rtc_enabled)
{
tp->tm_sec = 0;
tp->tm_min = 0;
tp->tm_hour = 0;
/* Jan 1, 1970 was a Thursday */
tp->tm_wday = 4;
tp->tm_mday = 1;
tp->tm_mon = 0;
tp->tm_year = 70;
return -EAGAIN;
}
/* Select to begin reading at the seconds register */
secaddr = DSXXXX_TIME_SECR;
msg[0].frequency = CONFIG_DS3231_I2C_FREQUENCY;
msg[0].addr = DS3231_I2C_ADDRESS;
msg[0].flags = 0;
msg[0].buffer = &secaddr;
msg[0].length = 1;
/* Set up to read 7 registers: secondss, minutes, hour, day-of-week, date,
* month, year
*/
msg[1].frequency = CONFIG_DS3231_I2C_FREQUENCY;
msg[1].addr = DS3231_I2C_ADDRESS;
msg[1].flags = I2C_M_READ;
msg[1].buffer = buffer;
msg[1].length = 7;
/* Read the seconds register again */
msg[2].frequency = CONFIG_DS3231_I2C_FREQUENCY;
msg[2].addr = DS3231_I2C_ADDRESS;
msg[2].flags = 0;
msg[2].buffer = &secaddr;
msg[2].length = 1;
msg[3].frequency = CONFIG_DS3231_I2C_FREQUENCY;
msg[3].addr = DS3231_I2C_ADDRESS;
msg[3].flags = I2C_M_READ;
msg[3].buffer = &seconds;
msg[3].length = 1;
/* Perform the transfer. The transfer may be performed repeatedly of the
* seconds values decreases, meaning that that was a rollover in the
* seconds.
*/
do
{
ret = I2C_TRANSFER(g_ds3231.i2c, msg, 4);
if (ret < 0)
{
rtcerr("ERROR: I2C_TRANSFER failed: %d\n", ret);
return ret;
}
}
while ((buffer[0] & DSXXXX_TIME_SEC_BCDMASK) >
(seconds & DSXXXX_TIME_SEC_BCDMASK));
/* Format the return time */
/* Return seconds (0-61) */
tp->tm_sec = rtc_bcd2bin(buffer[0] & DSXXXX_TIME_SEC_BCDMASK);
/* Return minutes (0-59) */
tp->tm_min = rtc_bcd2bin(buffer[1] & DSXXXX_TIME_MIN_BCDMASK);
/* Return hour (0-23). This assumes 24-hour time was set. */
tp->tm_hour = rtc_bcd2bin(buffer[2] & DSXXXX_TIME_HOUR24_BCDMASK);
/* Return the day of the week (0-6) */
tp->tm_wday = (rtc_bcd2bin(buffer[3]) & DSXXXX_TIME_DAY_MASK) - 1;
/* Return the day of the month (1-31) */
tp->tm_mday = rtc_bcd2bin(buffer[4] & DSXXXX_TIME_DATE_BCDMASK);
/* Return the month (0-11) */
tp->tm_mon = rtc_bcd2bin(buffer[5] & DSXXXX_TIME_MONTH_BCDMASK) - 1;
/* Return the years since 1900 */
tmp = rtc_bcd2bin(buffer[6] & DSXXXX_TIME_YEAR_BCDMASK);
#if defined(CONFIG_RTC_DS3231) || defined(CONFIG_RTC_DS3232)
if ((buffer[5] & DS323X_TIME_CENTURY_MASK) == DS323X_TIME_1900)
{
tp->tm_year = tmp;
}
else
{
tp->tm_year = tmp + 100;
}
#else
/* No century indicator.
* The RTC will hold years since 1968 (a leap year like 2000)
*/
tp->tm_year = tmp + 68;
#endif
rtc_dumptime(tp, "Returning");
return OK;
}
/****************************************************************************
* Name: up_rtc_settime
*
* Description:
* Set the RTC to the provided time. All RTC implementations must be able
* to set their time based on a standard timespec.
*
* Input Parameters:
* tp - the time to use
*
* Returned Value:
* Zero (OK) on success; a negated errno on failure
*
****************************************************************************/
int up_rtc_settime(FAR const struct timespec *tp)
{
struct i2c_msg_s msg[3];
struct tm newtm;
time_t newtime;
uint8_t buffer[8];
uint8_t seconds;
uint8_t century;
uint8_t year;
int ret;
/* If this function is called before the RTC has been initialized then just
* return an error.
*/
if (!g_rtc_enabled)
{
return -EAGAIN;
}
rtcinfo("Setting time tp=(%d,%d)\n", (int)tp->tv_sec, (int)tp->tv_nsec);
/* Get the broken out time */
newtime = (time_t)tp->tv_sec;
if (tp->tv_nsec >= 500000000)
{
/* Round up */
newtime++;
}
if (localtime_r(&newtime, &newtm) == NULL)
{
rtcerr("ERROR: localtime_r failed\n");
return -EINVAL;
}
rtc_dumptime(&newtm, "New time");
/* Construct the message */
/* Write starting with the seconds register */
buffer[0] = DSXXXX_TIME_SECR;
/* Save seconds (0-59) converted to BCD */
buffer[1] = rtc_bin2bcd(newtm.tm_sec);
/* Save minutes (0-59) converted to BCD */
buffer[2] = rtc_bin2bcd(newtm.tm_min);
/* Save hour (0-23) with 24-hour time indication */
buffer[3] = rtc_bin2bcd(newtm.tm_hour) | DSXXXX_TIME_24;
/* Save the day of the week (1-7) */
buffer[4] = rtc_bin2bcd(newtm.tm_wday + 1);
/* Save the day of the month (1-31) */
buffer[5] = rtc_bin2bcd(newtm.tm_mday);
#if defined(CONFIG_RTC_DS3231) || defined(CONFIG_RTC_DS3232)
/* Handle years in the 20th vs the 21st century */
if (newtm.tm_year < 100)
{
/* Convert years in the range 1900-1999 */
century = DS323X_TIME_1900;
year = newtm.tm_year;
}
else
{
/* Convert years in the range 2000-2099 */
century = DS323X_TIME_2000;
year = newtm.tm_year - 100;
}
#else
/* Use years since 1968 (a leap year like 2000) */
century = 0;
year = newtm.tm_year - 68;
#endif
/* Save the month (1-12) with century */
buffer[6] = rtc_bin2bcd(newtm.tm_mon + 1) | century;
/* Save the year */
buffer[7] = rtc_bin2bcd(year);
/* Setup the I2C message */
msg[0].frequency = CONFIG_DS3231_I2C_FREQUENCY;
msg[0].addr = DS3231_I2C_ADDRESS;
msg[0].flags = 0;
msg[0].buffer = buffer;
msg[0].length = 8;
/* Read back the seconds register */
msg[1].frequency = CONFIG_DS3231_I2C_FREQUENCY;
msg[1].addr = DS3231_I2C_ADDRESS;
msg[1].flags = 0;
msg[1].buffer = buffer;
msg[1].length = 1;
msg[2].frequency = CONFIG_DS3231_I2C_FREQUENCY;
msg[2].addr = DS3231_I2C_ADDRESS;
msg[2].flags = I2C_M_READ;
msg[2].buffer = &seconds;
msg[2].length = 1;
/* Perform the transfer. This transfer will be repeated if the seconds
* count rolls over to a smaller value while writing.
*/
do
{
ret = I2C_TRANSFER(g_ds3231.i2c, msg, 3);
if (ret < 0)
{
rtcerr("ERROR: I2C_TRANSFER failed: %d\n", ret);
return ret;
}
}
while ((buffer[1] & DSXXXX_TIME_SEC_BCDMASK) >
(seconds & DSXXXX_TIME_SEC_BCDMASK));
return OK;
}
#endif /* CONFIG_RTC_DSXXXX */
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