Go - Dual Button Bricklet

This is the description of the Go API bindings for the Dual Button Bricklet. General information and technical specifications for the Dual Button 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).

Callback

Download (example_callback.go)

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package main

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

const ADDR string = "localhost:4223"
const UID string = "XYZ" // Change XYZ to the UID of your Dual Button Bricklet.

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

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

    db.RegisterStateChangedCallback(func(buttonL dual_button_bricklet.ButtonState, buttonR dual_button_bricklet.ButtonState, ledL dual_button_bricklet.LEDState, ledR dual_button_bricklet.LEDState) {

        if buttonL == dual_button_bricklet.ButtonStatePressed {
            fmt.Println("Left Button: Pressed")
        } else if buttonL == dual_button_bricklet.ButtonStateReleased {
            fmt.Println("Left Button: Released")
        }

        if buttonR == dual_button_bricklet.ButtonStatePressed {
            fmt.Println("Right Button: Pressed")
        } else if buttonR == dual_button_bricklet.ButtonStateReleased {
            fmt.Println("Right Button: Released")
        }

        fmt.Println()
    })

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

API

The Dual Button Bricklet's API is defined in the package github.com/Tinkerforge/go-api-bindings/dual_button_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 NewDualButtonBricklet(uid string, ipcon *IPConnection)(device DualButtonBricklet, err error)

Creates a new DualButtonBricklet 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 (*DualButtonBricklet)SetLEDState(ledL LEDState, ledR LEDState)(err error)

Sets the state of the LEDs. Possible states are:

  • 0 = AutoToggleOn: Enables auto toggle with initially enabled LED.
  • 1 = AutoToggleOff: Activates auto toggle with initially disabled LED.
  • 2 = On: Enables LED (auto toggle is disabled).
  • 3 = Off: Disables LED (auto toggle is disabled).

In auto toggle mode the LED is toggled automatically at each press of a button.

If you just want to set one of the LEDs and don't know the current state of the other LED, you can get the state with (*DualButtonBricklet) GetLEDState or you can use (*DualButtonBricklet) SetSelectedLEDState.

The default value is (1, 1).

The following constants are available for this function:

  • LEDStateAutoToggleOn = 0
  • LEDStateAutoToggleOff = 1
  • LEDStateOn = 2
  • LEDStateOff = 3
func (*DualButtonBricklet)GetLEDState()(ledL LEDState, ledR LEDState, err error)

Returns the current state of the LEDs, as set by (*DualButtonBricklet) SetLEDState.

The following constants are available for this function:

  • LEDStateAutoToggleOn = 0
  • LEDStateAutoToggleOff = 1
  • LEDStateOn = 2
  • LEDStateOff = 3
func (*DualButtonBricklet)GetButtonState()(buttonL ButtonState, buttonR ButtonState, err error)

Returns the current state for both buttons. Possible states are:

  • 0 = pressed
  • 1 = released

The following constants are available for this function:

  • ButtonStatePressed = 0
  • ButtonStateReleased = 1

Advanced Functions

func (*DualButtonBricklet)SetSelectedLEDState(led LED, state LEDState)(err error)

Sets the state of the selected LED (0 or 1).

The other LED remains untouched.

The following constants are available for this function:

  • LEDLeft = 0
  • LEDRight = 1
  • LEDStateAutoToggleOn = 0
  • LEDStateAutoToggleOff = 1
  • LEDStateOn = 2
  • LEDStateOff = 3
func (*DualButtonBricklet)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 (*DualButtonBricklet)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 (*DualButtonBricklet) 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 (*DualButtonBricklet) SetResponseExpected for the list of function ID constants available for this function.

func (*DualButtonBricklet)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:

  • FunctionSetLEDState = 1
  • FunctionSetSelectedLEDState = 5
func (*DualButtonBricklet)SetResponseExpectedAll(responseExpected bool)(err error)

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

func (*DualButtonBricklet)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

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 (*DualButtonBricklet)RegisterStateChangedCallback(func(buttonL ButtonState, buttonR ButtonState, ledL LEDState, ledR LEDState))(callbackID uint64)

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

This callback is called whenever a button is pressed.

Possible states for buttons are:

  • 0 = pressed
  • 1 = released

Possible states for LEDs are:

  • 0 = AutoToggleOn: Auto toggle enabled and LED on.
  • 1 = AutoToggleOff: Auto toggle enabled and LED off.
  • 2 = On: LED on (auto toggle is disabled).
  • 3 = Off: LED off (auto toggle is disabled).

The following constants are available for this function:

  • ButtonStatePressed = 0
  • ButtonStateReleased = 1
  • LEDStateAutoToggleOn = 0
  • LEDStateAutoToggleOff = 1
  • LEDStateOn = 2
  • LEDStateOff = 3

Constants

dual_button_bricklet.DeviceIdentifier

This constant is used to identify a Dual Button Bricklet.

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

dual_button_bricklet.DeviceDisplayName

This constant represents the human readable name of a Dual Button Bricklet.