Go - Joystick Bricklet

This is the description of the Go API bindings for the Joystick Bricklet. General information and technical specifications for the Joystick 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/joystick_bricklet"
)

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

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    j, _ := joystick_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 position.
    x, y, _ := j.GetPosition()

    fmt.Printf("Position [X]: \n", x)
    fmt.Printf("Position [Y]: \n", y)

    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/joystick_bricklet"
)

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

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

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

    j.RegisterPressedCallback(func() {
        fmt.Println("Pressed")
    })

    j.RegisterReleasedCallback(func() {
        fmt.Println("Released")
    })

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

Find Borders

Download (example_find_borders.go)

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package main

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

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

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    j, _ := joystick_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 threshold receivers with a debounce time of 0.2 seconds (200ms).
    j.SetDebouncePeriod(200)

    j.RegisterPositionReachedCallback(func(x int16, y int16) {
        if y == 100 {
            fmt.Println("Top")
        } else if y == -100 {
            fmt.Println("Bottom")
        } else if x == 100 {
            fmt.Println("Right")
        } else if x == -100 {
            fmt.Println("Left")
        }
        fmt.Println()
    })

    // Configure threshold for position "outside of -99, -99 to 99, 99".
    j.SetPositionCallbackThreshold('o', -99, 99, -99, 99)

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

API

The Joystick Bricklet API is defined in the package github.com/Tinkerforge/go-api-bindings/joystick_bricklet

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

  • DeviceErrorSuccess = 0
  • DeviceErrorInvalidParameter = 1
  • DeviceErrorFunctionNotSupported = 2
  • DeviceErrorUnknownError = 3

which correspond to the values returned from Bricks and Bricklets.

All functions listed below are thread-safe.

Basic Functions

func NewJoystickBricklet(uid string, ipcon *IPConnection) (device JoystickBricklet, err error)

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

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

func (*JoystickBricklet) GetPosition() (x int16, y int16, err error)

Returns the position of the joystick. The value ranges between -100 and 100 for both axis. The middle position of the joystick is x=0, y=0. The returned values are averaged and calibrated (see Calibrate()).

If you want to get the position periodically, it is recommended to use the RegisterPositionCallback callback and set the period with SetPositionCallbackPeriod().

func (*JoystickBricklet) IsPressed() (pressed bool, err error)

Returns true if the button is pressed and false otherwise.

It is recommended to use the RegisterPressedCallback and RegisterReleasedCallback callbacks to handle the button.

Advanced Functions

func (*JoystickBricklet) GetAnalogValue() (x uint16, y uint16, err error)

Returns the values as read by a 12-bit analog-to-digital converter. The values are between 0 and 4095 for both axis.

Note

The values returned by GetPosition() are averaged over several samples to yield less noise, while GetAnalogValue() gives back raw unfiltered analog values. The only reason to use GetAnalogValue() is, if you need the full resolution of the analog-to-digital converter.

If you want the analog values periodically, it is recommended to use the RegisterAnalogValueCallback callback and set the period with SetAnalogValueCallbackPeriod().

func (*JoystickBricklet) Calibrate() (err error)

Calibrates the middle position of the joystick. If your Joystick Bricklet does not return x=0 and y=0 in the middle position, call this function while the joystick is standing still in the middle position.

The resulting calibration will be saved on the EEPROM of the Joystick Bricklet, thus you only have to calibrate it once.

func (*JoystickBricklet) 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 (*JoystickBricklet) 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 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.

func (*JoystickBricklet) 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:

  • FunctionCalibrate = 4
  • FunctionSetPositionCallbackPeriod = 5
  • FunctionSetAnalogValueCallbackPeriod = 7
  • FunctionSetPositionCallbackThreshold = 9
  • FunctionSetAnalogValueCallbackThreshold = 11
  • FunctionSetDebouncePeriod = 13
func (*JoystickBricklet) SetResponseExpectedAll(responseExpected bool) (err error)

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

func (*JoystickBricklet) 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 (*JoystickBricklet) SetPositionCallbackPeriod(period uint32) (err error)

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

The RegisterPositionCallback callback is only triggered if the position has changed since the last triggering.

The default value is 0.

func (*JoystickBricklet) GetPositionCallbackPeriod() (period uint32, err error)

Returns the period as set by SetPositionCallbackPeriod().

func (*JoystickBricklet) SetAnalogValueCallbackPeriod(period uint32) (err error)

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

The RegisterAnalogValueCallback callback is only triggered if the analog values have changed since the last triggering.

The default value is 0.

func (*JoystickBricklet) GetAnalogValueCallbackPeriod() (period uint32, err error)

Returns the period as set by SetAnalogValueCallbackPeriod().

func (*JoystickBricklet) SetPositionCallbackThreshold(option ThresholdOption, minX int16, maxX int16, minY int16, maxY int16) (err error)

Sets the thresholds for the RegisterPositionReachedCallback callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the position is outside the min and max values
'i' Callback is triggered when the position is inside the min and max values
'<' Callback is triggered when the position is smaller than the min values (max is ignored)
'>' Callback is triggered when the position is greater than the min values (max is ignored)

The default value is ('x', 0, 0, 0, 0).

The following constants are available for this function:

  • ThresholdOptionOff = 'x'
  • ThresholdOptionOutside = 'o'
  • ThresholdOptionInside = 'i'
  • ThresholdOptionSmaller = '<'
  • ThresholdOptionGreater = '>'
func (*JoystickBricklet) GetPositionCallbackThreshold() (option ThresholdOption, minX int16, maxX int16, minY int16, maxY int16, err error)

Returns the threshold as set by SetPositionCallbackThreshold().

The following constants are available for this function:

  • ThresholdOptionOff = 'x'
  • ThresholdOptionOutside = 'o'
  • ThresholdOptionInside = 'i'
  • ThresholdOptionSmaller = '<'
  • ThresholdOptionGreater = '>'
func (*JoystickBricklet) SetAnalogValueCallbackThreshold(option ThresholdOption, minX uint16, maxX uint16, minY uint16, maxY uint16) (err error)

Sets the thresholds for the RegisterAnalogValueReachedCallback callback.

The following options are possible:

Option Description
'x' Callback is turned off
'o' Callback is triggered when the analog values are outside the min and max values
'i' Callback is triggered when the analog values are inside the min and max values
'<' Callback is triggered when the analog values are smaller than the min values (max is ignored)
'>' Callback is triggered when the analog values are greater than the min values (max is ignored)

The default value is ('x', 0, 0, 0, 0).

The following constants are available for this function:

  • ThresholdOptionOff = 'x'
  • ThresholdOptionOutside = 'o'
  • ThresholdOptionInside = 'i'
  • ThresholdOptionSmaller = '<'
  • ThresholdOptionGreater = '>'
func (*JoystickBricklet) GetAnalogValueCallbackThreshold() (option ThresholdOption, minX uint16, maxX uint16, minY uint16, maxY uint16, err error)

Returns the threshold as set by SetAnalogValueCallbackThreshold().

The following constants are available for this function:

  • ThresholdOptionOff = 'x'
  • ThresholdOptionOutside = 'o'
  • ThresholdOptionInside = 'i'
  • ThresholdOptionSmaller = '<'
  • ThresholdOptionGreater = '>'
func (*JoystickBricklet) SetDebouncePeriod(debounce uint32) (err error)

Sets the period in ms with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

The default value is 100.

func (*JoystickBricklet) GetDebouncePeriod() (debounce uint32, err error)

Returns the debounce period as set by SetDebouncePeriod().

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 (*JoystickBricklet) RegisterPositionCallback(func(x int16, y int16)) (registrationId uint64)

A callback can be registered for this event with the RegisterPositionCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterPositionCallback(registrationId uint64) function.

This callback is triggered periodically with the period that is set by SetPositionCallbackPeriod(). The callback parameter is the position of the joystick.

The RegisterPositionCallback callback is only triggered if the position has changed since the last triggering.

func (*JoystickBricklet) RegisterAnalogValueCallback(func(x uint16, y uint16)) (registrationId uint64)

A callback can be registered for this event with the RegisterAnalogValueCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterAnalogValueCallback(registrationId uint64) function.

This callback is triggered periodically with the period that is set by SetAnalogValueCallbackPeriod(). The callback parameters are the analog values of the joystick.

The RegisterAnalogValueCallback callback is only triggered if the values have changed since the last triggering.

func (*JoystickBricklet) RegisterPositionReachedCallback(func(x int16, y int16)) (registrationId uint64)

A callback can be registered for this event with the RegisterPositionReachedCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterPositionReachedCallback(registrationId uint64) function.

This callback is triggered when the threshold as set by SetPositionCallbackThreshold() is reached. The callback parameters are the position of the joystick.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by SetDebouncePeriod().

func (*JoystickBricklet) RegisterAnalogValueReachedCallback(func(x uint16, y uint16)) (registrationId uint64)

A callback can be registered for this event with the RegisterAnalogValueReachedCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterAnalogValueReachedCallback(registrationId uint64) function.

This callback is triggered when the threshold as set by SetAnalogValueCallbackThreshold() is reached. The callback parameters are the analog values of the joystick.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by SetDebouncePeriod().

func (*JoystickBricklet) RegisterPressedCallback(func()) (registrationId uint64)

A callback can be registered for this event with the RegisterPressedCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterPressedCallback(registrationId uint64) function.

This callback is triggered when the button is pressed.

func (*JoystickBricklet) RegisterReleasedCallback(func()) (registrationId uint64)

A callback can be registered for this event with the RegisterReleasedCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterReleasedCallback(registrationId uint64) function.

This callback is triggered when the button is released.

Constants

joystick_bricklet.DeviceIdentifier

This constant is used to identify a Joystick Bricklet.

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

joystick_bricklet.DeviceDisplayName

This constant represents the human readable name of a Joystick Bricklet.