Go - Real-Time Clock Bricklet

This is the description of the Go 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 Go API bindings is part of their general description. Additional documentation can be found on godoc.org.

Examples

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

Simple

Download (example_simple.go)

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package main

import (
    "fmt"
    "github.com/Tinkerforge/go-api-bindings/ipconnection"
    "github.com/Tinkerforge/go-api-bindings/real_time_clock_bricklet"
)

const ADDR string = "localhost:4223"
const UID string = "XYZ" // Change XYZ to the UID of your Real-Time Clock Bricklet.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    rtc, _ := real_time_clock_bricklet.New(UID, &ipcon) // Create device object.

    ipcon.Connect(ADDR) // Connect to brickd.
    defer ipcon.Disconnect()
    // Don't use device before ipcon is connected.

    // Get current date and time.
    year, month, day, hour, minute, second, centisecond, weekday, _ := rtc.GetDateTime()

    fmt.Printf("Year: \n", year)
    fmt.Printf("Month: \n", month)
    fmt.Printf("Day: \n", day)
    fmt.Printf("Hour: \n", hour)
    fmt.Printf("Minute: \n", minute)
    fmt.Printf("Second: \n", second)
    fmt.Printf("Centisecond: \n", centisecond)

    if weekday == real_time_clock_bricklet.WeekdayMonday {
        fmt.Println("Weekday: Monday")
    } else if weekday == real_time_clock_bricklet.WeekdayTuesday {
        fmt.Println("Weekday: Tuesday")
    } else if weekday == real_time_clock_bricklet.WeekdayWednesday {
        fmt.Println("Weekday: Wednesday")
    } else if weekday == real_time_clock_bricklet.WeekdayThursday {
        fmt.Println("Weekday: Thursday")
    } else if weekday == real_time_clock_bricklet.WeekdayFriday {
        fmt.Println("Weekday: Friday")
    } else if weekday == real_time_clock_bricklet.WeekdaySaturday {
        fmt.Println("Weekday: Saturday")
    } else if weekday == real_time_clock_bricklet.WeekdaySunday {
        fmt.Println("Weekday: Sunday")
    }

    // Get current timestamp.
    timestamp, _ := rtc.GetTimestamp()
    fmt.Printf("Timestamp:  ms\n", timestamp)

    fmt.Print("Press enter to exit.")
    fmt.Scanln()
}

Callback

Download (example_callback.go)

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package main

import (
    "fmt"
    "github.com/Tinkerforge/go-api-bindings/ipconnection"
    "github.com/Tinkerforge/go-api-bindings/real_time_clock_bricklet"
)

const ADDR string = "localhost:4223"
const UID string = "XYZ" // Change XYZ to the UID of your Real-Time Clock Bricklet.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    rtc, _ := real_time_clock_bricklet.New(UID, &ipcon) // Create device object.

    ipcon.Connect(ADDR) // Connect to brickd.
    defer ipcon.Disconnect()
    // Don't use device before ipcon is connected.

    rtc.RegisterDateTimeCallback(func(year uint16, month uint8, day uint8, hour uint8, minute uint8, second uint8, centisecond uint8, weekday real_time_clock_bricklet.Weekday, timestamp int64) {
        fmt.Printf("Year: %d\n", year)
        fmt.Printf("Month: %d\n", month)
        fmt.Printf("Day: %d\n", day)
        fmt.Printf("Hour: %d\n", hour)
        fmt.Printf("Minute: %d\n", minute)
        fmt.Printf("Second: %d\n", second)
        fmt.Printf("Centisecond: %d\n", centisecond)

        if weekday == real_time_clock_bricklet.WeekdayMonday {
            fmt.Println("Weekday: Monday")
        } else if weekday == real_time_clock_bricklet.WeekdayTuesday {
            fmt.Println("Weekday: Tuesday")
        } else if weekday == real_time_clock_bricklet.WeekdayWednesday {
            fmt.Println("Weekday: Wednesday")
        } else if weekday == real_time_clock_bricklet.WeekdayThursday {
            fmt.Println("Weekday: Thursday")
        } else if weekday == real_time_clock_bricklet.WeekdayFriday {
            fmt.Println("Weekday: Friday")
        } else if weekday == real_time_clock_bricklet.WeekdaySaturday {
            fmt.Println("Weekday: Saturday")
        } else if weekday == real_time_clock_bricklet.WeekdaySunday {
            fmt.Println("Weekday: Sunday")
        }

        fmt.Printf("Timestamp: %d\n", timestamp)
        fmt.Println()
    })

    // Set period for date and time receiver 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)

    fmt.Print("Press enter to exit.")
    fmt.Scanln()
}

API

The Real-Time Clock Bricklet's API is defined in the package github.com/Tinkerforge/go-api-bindings/real_time_clock_bricklet

Nearly every function of the Go bindings can return an BrickletError, implementing the error interface. The error can have one of the following values:

  • BrickletErrorSuccess = 0
  • BrickletErrorInvalidParameter = 1
  • BrickletErrorFunctionNotSupported = 2
  • BrickletErrorUnknownError = 3

which correspond to the values returned from Bricks and Bricklets.

All functions listed below are thread-safe.

Basic Functions

func NewRealTimeClockBricklet(uid string, ipcon *IPConnection)(device RealTimeClockBricklet, err error)

Creates a new RealTimeClockBricklet object with the unique device ID uid and adds it to the IPConnection ipcon:

This device object can be used after the IP connection has been connected (see examples above).

func (*RealTimeClockBricklet)SetDateTime(year uint16, month uint8, day uint8, hour uint8, minute uint8, second uint8, centisecond uint8, weekday Weekday)(err error)

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:

  • WeekdayMonday = 1
  • WeekdayTuesday = 2
  • WeekdayWednesday = 3
  • WeekdayThursday = 4
  • WeekdayFriday = 5
  • WeekdaySaturday = 6
  • WeekdaySunday = 7
func (*RealTimeClockBricklet)GetDateTime()(year uint16, month uint8, day uint8, hour uint8, minute uint8, second uint8, centisecond uint8, weekday Weekday, err error)

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:

  • WeekdayMonday = 1
  • WeekdayTuesday = 2
  • WeekdayWednesday = 3
  • WeekdayThursday = 4
  • WeekdayFriday = 5
  • WeekdaySaturday = 6
  • WeekdaySunday = 7
func (*RealTimeClockBricklet)GetTimestamp()(timestamp int64, err error)

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

func (*RealTimeClockBricklet)SetOffset(offset int8)(err error)

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.

func (*RealTimeClockBricklet)GetOffset()(offset int8, err error)

Returns the offset as set by (*RealTimeClockBricklet) SetOffset.

func (*RealTimeClockBricklet)GetAPIVersion()(apiVersion [3]uint8, err error)

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.

func (*RealTimeClockBricklet)GetResponseExpected(functionId uint8)(responseExpected bool, err error)

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 callback configuration functions it is enabled by default too, but can be disabled by (*RealTimeClockBricklet) 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 (*RealTimeClockBricklet) SetResponseExpected for the list of function ID constants available for this function.

func (*RealTimeClockBricklet)SetResponseExpected(functionId uint8, responseExpected bool)(err error)

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 callback 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:

  • FunctionSetDateTime = 1
  • FunctionSetOffset = 4
  • FunctionSetDateTimeCallbackPeriod = 6
  • FunctionSetAlarm = 8
func (*RealTimeClockBricklet)SetResponseExpectedAll(responseExpected bool)(err error)

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

func (*RealTimeClockBricklet)GetIdentity()(uid string, connectedUid string, position rune, hardwareVersion [3]uint8, firmwareVersion [3]uint8, deviceIdentifier uint16, err error)

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.

Callback Configuration Functions

func (*RealTimeClockBricklet)SetDateTimeCallbackPeriod(period uint32)(err error)

Sets the period in ms with which the (*RealTimeClockBricklet) RegisterDateTimeCallback callback is triggered periodically. A value of 0 turns the callback off.

The (*RealTimeClockBricklet) RegisterDateTimeCallback Callback 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).

func (*RealTimeClockBricklet)GetDateTimeCallbackPeriod()(period uint32, err error)

Returns the period as set by (*RealTimeClockBricklet) SetDateTimeCallbackPeriod.

New in version 2.0.1 (Plugin).

func (*RealTimeClockBricklet)SetAlarm(month AlarmMatch, day AlarmMatch, hour AlarmMatch, minute AlarmMatch, second AlarmMatch, weekday AlarmMatch, interval AlarmInterval)(err error)

Configures a repeatable alarm. The (*RealTimeClockBricklet) RegisterAlarmCallback 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.

The following constants are available for this function:

  • AlarmMatchDisabled = -1
  • AlarmIntervalDisabled = -1

New in version 2.0.1 (Plugin).

func (*RealTimeClockBricklet)GetAlarm()(month AlarmMatch, day AlarmMatch, hour AlarmMatch, minute AlarmMatch, second AlarmMatch, weekday AlarmMatch, interval AlarmInterval, err error)

Returns the alarm configuration as set by (*RealTimeClockBricklet) SetAlarm.

The following constants are available for this function:

  • AlarmMatchDisabled = -1
  • AlarmIntervalDisabled = -1

New in version 2.0.1 (Plugin).

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the corresponding Register*Callback function, which returns a unique callback ID. This ID can be used to deregister the callback later.

Note

Using callbacks 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.

func (*RealTimeClockBricklet)RegisterDateTimeCallback(func(year uint16, month uint8, day uint8, hour uint8, minute uint8, second uint8, centisecond uint8, weekday Weekday, timestamp int64))(callbackID uint64)

A callback can be registered for this event with the RegisterDateTimeCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterDateTimeCallback(callbackID uint64) function.

This callback is triggered periodically with the period that is set by (*RealTimeClockBricklet) SetDateTimeCallbackPeriod. The callback parameters are the same as for (*RealTimeClockBricklet) GetDateTime and (*RealTimeClockBricklet) GetTimestamp combined.

The (*RealTimeClockBricklet) RegisterDateTimeCallback callback is only triggered if the date or time changed since the last triggering.

The following constants are available for this function:

  • WeekdayMonday = 1
  • WeekdayTuesday = 2
  • WeekdayWednesday = 3
  • WeekdayThursday = 4
  • WeekdayFriday = 5
  • WeekdaySaturday = 6
  • WeekdaySunday = 7

New in version 2.0.1 (Plugin).

func (*RealTimeClockBricklet)RegisterAlarmCallback(func(year uint16, month uint8, day uint8, hour uint8, minute uint8, second uint8, centisecond uint8, weekday Weekday, timestamp int64))(callbackID uint64)

A callback can be registered for this event with the RegisterAlarmCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterAlarmCallback(callbackID uint64) function.

This callback is triggered every time the current date and time matches the configured alarm (see (*RealTimeClockBricklet) SetAlarm). The callback parameters are the same as for (*RealTimeClockBricklet) GetDateTime and (*RealTimeClockBricklet) GetTimestamp combined.

The following constants are available for this function:

  • WeekdayMonday = 1
  • WeekdayTuesday = 2
  • WeekdayWednesday = 3
  • WeekdayThursday = 4
  • WeekdayFriday = 5
  • WeekdaySaturday = 6
  • WeekdaySunday = 7

New in version 2.0.1 (Plugin).

Constants

real_time_clock_bricklet.DeviceIdentifier

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

The (*RealTimeClockBricklet) GetIdentity function and the (*IPConnection) RegisterEnumerateCallback callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

real_time_clock_bricklet.DeviceDisplayName

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