Ishraq Ibne Ashraf
and 1 contributors

NAME

Tinkerforge::BrickletRealTimeClock - Battery-backed real-time clock

CONSTANTS

DEVICE_IDENTIFIER

This constant is used to identify a Real-Time Clock Bricklet.

The get_identity() subroutine and the CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

DEVICE_DISPLAY_NAME

This constant represents the display name of a Real-Time Clock Bricklet.

CALLBACK_DATE_TIME

This constant is used with the register_callback() subroutine to specify the CALLBACK_DATE_TIME callback.

CALLBACK_ALARM

This constant is used with the register_callback() subroutine to specify the CALLBACK_ALARM callback.

FUNCTION_SET_DATE_TIME

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_GET_DATE_TIME

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_GET_TIMESTAMP

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_SET_OFFSET

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_GET_OFFSET

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_SET_DATE_TIME_CALLBACK_PERIOD

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_GET_DATE_TIME_CALLBACK_PERIOD

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_SET_ALARM

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_GET_ALARM

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTION_GET_IDENTITY

This constant is used with the get_response_expected(), set_response_expected() and set_response_expected_all() subroutines.

FUNCTIONS

new()

Creates an object with the unique device ID *uid* and adds it to the IP Connection *ipcon*.

set_date_time()

Sets the current date (including weekday) and the current time with hundredths of a second resolution.

Possible value ranges:

* Year: 2000 to 2099 * Month: 1 to 12 (January to December) * Day: 1 to 31 * Hour: 0 to 23 * Minute: 0 to 59 * Second: 0 to 59 * Centisecond: 0 to 99 * Weekday: 1 to 7 (Monday to Sunday)

If the backup battery is installed then the real-time clock keeps date and time even if the Bricklet is not powered by a Brick.

The real-time clock handles leap year and inserts the 29th of February accordingly. But leap seconds, time zones and daylight saving time are not handled.

get_date_time()

Returns the current date (including weekday) and the current time of the real-time clock with hundredths of a second resolution.

get_timestamp()

Returns the current date and the time of the real-time clock converted to milliseconds. The timestamp has an effective resolution of hundredths of a second.

set_offset()

Sets the offset the real-time clock should compensate for in 2.17 ppm steps between -277.76 ppm (-128) and +275.59 ppm (127).

The real-time clock time can deviate from the actual time due to the frequency deviation of its 32.768 kHz crystal. Even without compensation (factory default) the resulting time deviation should be at most ±20 ppm (±52.6 seconds per month).

This deviation can be calculated by comparing the same duration measured by the real-time clock (``rtc_duration``) an accurate reference clock (``ref_duration``).

For best results the configured offset should be set to 0 ppm first and then a duration of at least 6 hours should be measured.

The new offset (``new_offset``) can be calculated from the currently configured offset (``current_offset``) and the measured durations as follow::

  new_offset = current_offset - round(1000000 * (rtc_duration - ref_duration) / rtc_duration / 2.17)

If you want to calculate the offset, then we recommend using the calibration dialog in Brick Viewer, instead of doing it manually.

The offset is saved in the EEPROM of the Bricklet and only needs to be configured once.

get_offset()

Returns the offset as set by :func:`Set Offset`.

set_date_time_callback_period()

Sets the period in ms with which the :cb:`Date Time` callback is triggered periodically. A value of 0 turns the callback off.

The :cb:`Date Time` Callback is only triggered if the date or time changed since the last triggering.

The default value is 0.

.. versionadded:: 2.0.1$nbsp;(Plugin)

get_date_time_callback_period()

Returns the period as set by :func:`Set Date Time Callback Period`.

.. versionadded:: 2.0.1$nbsp;(Plugin)

set_alarm()

Configures a repeatable alarm. The :cb:`Alarm` callback is triggered if the current date and time matches the configured alarm.

Setting a parameter to -1 means that it should be disabled and doesn't take part in the match. Setting all parameters to -1 disables the alarm completely.

For example, to make the alarm trigger every day at 7:30 AM it can be configured as (-1, -1, 7, 30, -1, -1, -1). The hour is set to match 7 and the minute is set to match 30. The alarm is triggered if all enabled parameters match.

The interval has a special role. It allows to make the alarm reconfigure itself. This is useful if you need a repeated alarm that cannot be expressed by matching the current date and time. For example, to make the alarm trigger every 23 seconds it can be configured as (-1, -1, -1, -1, -1, -1, 23). Internally the Bricklet will take the current date and time, add 23 seconds to it and set the result as its alarm. The first alarm will be triggered 23 seconds after the call. Because the interval is not -1, the Bricklet will do the same again internally, take the current date and time, add 23 seconds to it and set that as its alarm. This results in a repeated alarm that triggers every 23 seconds.

The interval can also be used in combination with the other parameters. For example, configuring the alarm as (-1, -1, 7, 30, -1, -1, 300) results in an alarm that triggers every day at 7:30 AM and is then repeated every 5 minutes.

.. versionadded:: 2.0.1$nbsp;(Plugin)

get_alarm()

Returns the alarm configuration as set by :func:`Set Alarm`.

.. versionadded:: 2.0.1$nbsp;(Plugin)

get_identity()

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c' or 'd'.

The device identifier numbers can be found :ref:`here <device_identifier>`. |device_identifier_constant|