Java - Real-Time Clock Bricklet

This is the description of the Java API bindings for the Real-Time Clock Bricklet. General information and technical specifications for the Real-Time Clock Bricklet are summarized in its hardware description.

An installation guide for the Java API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Simple

Download (ExampleSimple.java)

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import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletRealTimeClock;
import com.tinkerforge.BrickletRealTimeClock.DateTime;

public class ExampleSimple {
    private static final String HOST = "localhost";
    private static final int PORT = 4223;

    // Change XYZ to the UID of your Real-Time Clock Bricklet
    private static final String UID = "XYZ";

    // Note: To make the example code cleaner we do not handle exceptions. Exceptions
    //       you might normally want to catch are described in the documentation
    public static void main(String args[]) throws Exception {
        IPConnection ipcon = new IPConnection(); // Create IP connection
        BrickletRealTimeClock rtc = new BrickletRealTimeClock(UID, ipcon); // Create device object

        ipcon.connect(HOST, PORT); // Connect to brickd
        // Don't use device before ipcon is connected

        // Get current date and time
        DateTime dateTime = rtc.getDateTime(); // Can throw com.tinkerforge.TimeoutException

        System.out.println("Year: " + dateTime.year);
        System.out.println("Month: " + dateTime.month);
        System.out.println("Day: " + dateTime.day);
        System.out.println("Hour: " + dateTime.hour);
        System.out.println("Minute: " + dateTime.minute);
        System.out.println("Second: " + dateTime.second);
        System.out.println("Centisecond: " + dateTime.centisecond);
        System.out.println("Weekday: " + dateTime.weekday);

        // Get current timestamp
        long timestamp = rtc.getTimestamp(); // Can throw com.tinkerforge.TimeoutException
        System.out.println("Timestamp: " + timestamp + " ms");

        System.out.println("Press key to exit"); System.in.read();
        ipcon.disconnect();
    }
}

Callback

Download (ExampleCallback.java)

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import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletRealTimeClock;

public class ExampleCallback {
    private static final String HOST = "localhost";
    private static final int PORT = 4223;

    // Change XYZ to the UID of your Real-Time Clock Bricklet
    private static final String UID = "XYZ";

    // Note: To make the example code cleaner we do not handle exceptions. Exceptions
    //       you might normally want to catch are described in the documentation
    public static void main(String args[]) throws Exception {
        IPConnection ipcon = new IPConnection(); // Create IP connection
        BrickletRealTimeClock rtc = new BrickletRealTimeClock(UID, ipcon); // Create device object

        ipcon.connect(HOST, PORT); // Connect to brickd
        // Don't use device before ipcon is connected

        // Add date and time listener
        rtc.addDateTimeListener(new BrickletRealTimeClock.DateTimeListener() {
            public void dateTime(int year, short month, short day, short hour,
                                 short minute, short second, short centisecond,
                                 short weekday, long timestamp) {
                System.out.println("Year: " + year);
                System.out.println("Month: " + month);
                System.out.println("Day: " + day);
                System.out.println("Hour: " + hour);
                System.out.println("Minute: " + minute);
                System.out.println("Second: " + second);
                System.out.println("Centisecond: " + centisecond);
                System.out.println("Weekday: " + weekday);
                System.out.println("Timestamp: " + timestamp);
                System.out.println("");
            }
        });

        // Set period for date and time callback to 5s (5000ms)
        // Note: The date and time callback is only called every 5 seconds
        //       if the date and time has changed since the last call!
        rtc.setDateTimeCallbackPeriod(5000);

        System.out.println("Press key to exit"); System.in.read();
        ipcon.disconnect();
    }
}

API

Generally, every method of the Java bindings that returns a value can throw a TimeoutException. This exception gets thrown if the device did not respond. If a cable based connection is used, it is unlikely that this exception gets thrown (assuming nobody unplugs the device). However, if a wireless connection is used, timeouts will occur if the distance to the device gets too big.

Beside the TimeoutException there is also a NotConnectedException that is thrown if a method needs to communicate with the device while the IP Connection is not connected.

Since Java does not support multiple return values and return by reference is not possible for primitive types, we use small classes that only consist of member variables. The member variables of the returned objects are described in the corresponding method descriptions.

The package for all Brick/Bricklet bindings and the IP Connection is com.tinkerforge.*

All methods listed below are thread-safe.

Basic Functions

public class BrickletRealTimeClock(String uid, IPConnection ipcon)

Creates an object with the unique device ID uid:

BrickletRealTimeClock realTimeClock = new BrickletRealTimeClock("YOUR_DEVICE_UID", ipcon);

This object can then be used after the IP Connection is connected (see examples above).

public void setDateTime(int year, short month, short day, short hour, short minute, short second, short centisecond, short weekday)

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.

The following constants are available for this function:

  • BrickletRealTimeClock.WEEKDAY_MONDAY = 1
  • BrickletRealTimeClock.WEEKDAY_TUESDAY = 2
  • BrickletRealTimeClock.WEEKDAY_WEDNESDAY = 3
  • BrickletRealTimeClock.WEEKDAY_THURSDAY = 4
  • BrickletRealTimeClock.WEEKDAY_FRIDAY = 5
  • BrickletRealTimeClock.WEEKDAY_SATURDAY = 6
  • BrickletRealTimeClock.WEEKDAY_SUNDAY = 7
public BrickletRealTimeClock.DateTime getDateTime()

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

The following constants are available for this function:

  • BrickletRealTimeClock.WEEKDAY_MONDAY = 1
  • BrickletRealTimeClock.WEEKDAY_TUESDAY = 2
  • BrickletRealTimeClock.WEEKDAY_WEDNESDAY = 3
  • BrickletRealTimeClock.WEEKDAY_THURSDAY = 4
  • BrickletRealTimeClock.WEEKDAY_FRIDAY = 5
  • BrickletRealTimeClock.WEEKDAY_SATURDAY = 6
  • BrickletRealTimeClock.WEEKDAY_SUNDAY = 7

The returned object has the public member variables int year, short month, short day, short hour, short minute, short second, short centisecond and short weekday.

public long getTimestamp()

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.

Advanced Functions

public void setOffset(byte 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.

public byte getOffset()

Returns the offset as set by setOffset().

public short[] getAPIVersion()

Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

public boolean getResponseExpected(short functionId)

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For listener configuration functions it is enabled by default too, but can be disabled by setResponseExpected(). For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

See setResponseExpected() for the list of function ID constants available for this function.

public void setResponseExpected(short functionId, boolean responseExpected)

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and listener configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following function ID constants are available for this function:

  • BrickletRealTimeClock.FUNCTION_SET_DATE_TIME = 1
  • BrickletRealTimeClock.FUNCTION_SET_OFFSET = 4
  • BrickletRealTimeClock.FUNCTION_SET_DATE_TIME_CALLBACK_PERIOD = 6
  • BrickletRealTimeClock.FUNCTION_SET_ALARM = 8
public void setResponseExpectedAll(boolean responseExpected)

Changes the response expected flag for all setter and listener configuration functions of this device at once.

public BrickletRealTimeClock.Identity getIdentity()

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 here. There is also a constant for the device identifier of this Bricklet.

The returned object has the public member variables String uid, String connectedUid, char position, short[] hardwareVersion, short[] firmwareVersion and int deviceIdentifier.

Listener Configuration Functions

public void setDateTimeCallbackPeriod(long period)

Sets the period in ms with which the DateTimeListener listener is triggered periodically. A value of 0 turns the listener off.

The DateTimeListener Listener is only triggered if the date or time changed since the last triggering.

The default value is 0.

New in version 2.0.1 (Plugin).

public long getDateTimeCallbackPeriod()

Returns the period as set by setDateTimeCallbackPeriod().

New in version 2.0.1 (Plugin).

public void setAlarm(byte month, byte day, byte hour, byte minute, byte second, byte weekday, int interval)

Configures a repeatable alarm. The AlarmListener listener 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.

The following constants are available for this function:

  • BrickletRealTimeClock.ALARM_MATCH_DISABLED = -1
  • BrickletRealTimeClock.ALARM_INTERVAL_DISABLED = -1

New in version 2.0.1 (Plugin).

public BrickletRealTimeClock.Alarm getAlarm()

Returns the alarm configuration as set by setAlarm().

The following constants are available for this function:

  • BrickletRealTimeClock.ALARM_MATCH_DISABLED = -1
  • BrickletRealTimeClock.ALARM_INTERVAL_DISABLED = -1

New in version 2.0.1 (Plugin).

The returned object has the public member variables byte month, byte day, byte hour, byte minute, byte second, byte weekday and int interval.

Listeners

Listeners can be registered to receive time critical or recurring data from the device. The registration is done with "add*Listener" functions of the device object.

The parameter is a listener class object, for example:

device.addExampleListener(new BrickletRealTimeClock.ExampleListener() {
    public void property(int value) {
        System.out.println("Value: " + value);
    }
});

The available listener classes with inherent methods to be overwritten are described below. It is possible to add several listeners and to remove them with the corresponding "remove*Listener" function.

Note

Using listeners for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

public class BrickletRealTimeClock.DateTimeListener()

This listener can be added with the addDateTimeListener() function. An added listener can be removed with the removeDateTimeListener() function.

public void dateTime(int year, short month, short day, short hour, short minute, short second, short centisecond, short weekday, long timestamp)

This listener is triggered periodically with the period that is set by setDateTimeCallbackPeriod(). The parameters are the same as for getDateTime() and getTimestamp() combined.

The DateTimeListener listener is only triggered if the date or time changed since the last triggering.

The following constants are available for this function:

  • BrickletRealTimeClock.WEEKDAY_MONDAY = 1
  • BrickletRealTimeClock.WEEKDAY_TUESDAY = 2
  • BrickletRealTimeClock.WEEKDAY_WEDNESDAY = 3
  • BrickletRealTimeClock.WEEKDAY_THURSDAY = 4
  • BrickletRealTimeClock.WEEKDAY_FRIDAY = 5
  • BrickletRealTimeClock.WEEKDAY_SATURDAY = 6
  • BrickletRealTimeClock.WEEKDAY_SUNDAY = 7

New in version 2.0.1 (Plugin).

public class BrickletRealTimeClock.AlarmListener()

This listener can be added with the addAlarmListener() function. An added listener can be removed with the removeAlarmListener() function.

public void alarm(int year, short month, short day, short hour, short minute, short second, short centisecond, short weekday, long timestamp)

This listener is triggered every time the current date and time matches the configured alarm (see setAlarm()). The parameters are the same as for getDateTime() and getTimestamp() combined.

The following constants are available for this function:

  • BrickletRealTimeClock.WEEKDAY_MONDAY = 1
  • BrickletRealTimeClock.WEEKDAY_TUESDAY = 2
  • BrickletRealTimeClock.WEEKDAY_WEDNESDAY = 3
  • BrickletRealTimeClock.WEEKDAY_THURSDAY = 4
  • BrickletRealTimeClock.WEEKDAY_FRIDAY = 5
  • BrickletRealTimeClock.WEEKDAY_SATURDAY = 6
  • BrickletRealTimeClock.WEEKDAY_SUNDAY = 7

New in version 2.0.1 (Plugin).

Constants

public static final int BrickletRealTimeClock.DEVICE_IDENTIFIER

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

The getIdentity() function and the EnumerateListener listener of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

public static final String BrickletRealTimeClock.DEVICE_DISPLAY_NAME

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