Software / API Bindings / Go / API Reference and Examples / Bricklets / Joystick Bricklet

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)

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

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

Callback¶

Download (example_callback.go)

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)

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 ipconnection.DeviceError, implementing the error interface. The error can have one of the following values:

ipconnection.DeviceErrorSuccess = 0
ipconnection.DeviceErrorInvalidParameter = 1
ipconnection.DeviceErrorFunctionNotSupported = 2
ipconnection.DeviceErrorUnknownError = 3

which correspond to the values returned from Bricks and Bricklets.

All functions listed below are thread-safe.

Basic Functions¶

func joystick_bricklet.New(uid string, ipcon *IPConnection) (device JoystickBricklet, err error)¶

Parameters:	uid – Type: string ipcon – Type: *IPConnection
Returns:	device – Type: JoystickBricklet err – Type: error

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

device, err := joystick_bricklet.New("YOUR_DEVICE_UID", &ipcon)

This device object can be used after the IPConnection has been connected.

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

Returns:	x – Type: int16, Range: [-100 to 100] y – Type: int16, Range: [-100 to 100] err – Type: error

Returns the position of the joystick. 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 PositionCallback callback and set the period with SetPositionCallbackPeriod().

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

Returns:	pressed – Type: bool err – Type: error

Returns true if the button is pressed and false otherwise.

It is recommended to use the PressedCallback and ReleasedCallback callbacks to handle the button.

Advanced Functions¶

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

Returns:	x – Type: uint16, Range: [0 to 2¹² - 1] y – Type: uint16, Range: [0 to 2¹² - 1] err – Type: error

Returns the values as read by a 12-bit analog-to-digital converter.

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 AnalogValueCallback callback and set the period with SetAnalogValueCallbackPeriod().

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

Returns:	err – Type: 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) GetIdentity() (uid string, connectedUid string, position rune, hardwareVersion [3]uint8, firmwareVersion [3]uint8, deviceIdentifier uint16, err error)¶

Returns:

Returns:	uid – Type: string, Length: up to 8 connectedUid – Type: string, Length: up to 8 position – Type: rune, Range: ['a' to 'h', 'z'] hardwareVersion – Type: [3]uint8 0: major – Type: uint8, Range: [0 to 255] 1: minor – Type: uint8, Range: [0 to 255] 2: revision – Type: uint8, Range: [0 to 255] firmwareVersion – Type: [3]uint8 0: major – Type: uint8, Range: [0 to 255] 1: minor – Type: uint8, Range: [0 to 255] 2: revision – Type: uint8, Range: [0 to 255] deviceIdentifier – Type: uint16, Range: [0 to 2¹⁶ - 1] err – Type: error

uid – Type: string, Length: up to 8
connectedUid – Type: string, Length: up to 8
position – Type: rune, Range: ['a' to 'h', 'z']
hardwareVersion – Type: [3]uint8

0: major – Type: uint8, Range: [0 to 255]
1: minor – Type: uint8, Range: [0 to 255]
2: revision – Type: uint8, Range: [0 to 255]

firmwareVersion – Type: [3]uint8

0: major – Type: uint8, Range: [0 to 255]
1: minor – Type: uint8, Range: [0 to 255]
2: revision – Type: uint8, Range: [0 to 255]

deviceIdentifier – Type: uint16, Range: [0 to 2¹⁶ - 1]
err – Type: 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', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

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)¶

Parameters:	period – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0
Returns:	err – Type: error

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

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

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

Returns:	period – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0 err – Type: error

Returns the period as set by SetPositionCallbackPeriod().

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

Parameters:	period – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0
Returns:	err – Type: error

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

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

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

Returns:	period – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0 err – Type: error

Returns the period as set by SetAnalogValueCallbackPeriod().

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

Parameters:	option – Type: rune, Range: See constants, Default: 'x' minX – Type: int16, Range: [-2¹⁵ to 2¹⁵ - 1], Default: 0 maxX – Type: int16, Range: [-2¹⁵ to 2¹⁵ - 1], Default: 0 minY – Type: int16, Range: [-2¹⁵ to 2¹⁵ - 1], Default: 0 maxY – Type: int16, Range: [-2¹⁵ to 2¹⁵ - 1], Default: 0
Returns:	err – Type: error

Sets the thresholds for the PositionReachedCallback 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 following constants are available for this function:

For option:

joystick_bricklet.ThresholdOptionOff = 'x'
joystick_bricklet.ThresholdOptionOutside = 'o'
joystick_bricklet.ThresholdOptionInside = 'i'
joystick_bricklet.ThresholdOptionSmaller = '<'
joystick_bricklet.ThresholdOptionGreater = '>'

func (*JoystickBricklet) GetPositionCallbackThreshold() (option rune, minX int16, maxX int16, minY int16, maxY int16, err error)¶

Returns:	option – Type: rune, Range: See constants, Default: 'x' minX – Type: int16, Range: [-2¹⁵ to 2¹⁵ - 1], Default: 0 maxX – Type: int16, Range: [-2¹⁵ to 2¹⁵ - 1], Default: 0 minY – Type: int16, Range: [-2¹⁵ to 2¹⁵ - 1], Default: 0 maxY – Type: int16, Range: [-2¹⁵ to 2¹⁵ - 1], Default: 0 err – Type: error

Returns the threshold as set by SetPositionCallbackThreshold().

The following constants are available for this function:

For option:

joystick_bricklet.ThresholdOptionOff = 'x'
joystick_bricklet.ThresholdOptionOutside = 'o'
joystick_bricklet.ThresholdOptionInside = 'i'
joystick_bricklet.ThresholdOptionSmaller = '<'
joystick_bricklet.ThresholdOptionGreater = '>'

func (*JoystickBricklet) SetAnalogValueCallbackThreshold(option rune, minX uint16, maxX uint16, minY uint16, maxY uint16) (err error)¶

Parameters:	option – Type: rune, Range: See constants, Default: 'x' minX – Type: uint16, Range: [0 to 2¹⁶ - 1], Default: 0 maxX – Type: uint16, Range: [0 to 2¹⁶ - 1], Default: 0 minY – Type: uint16, Range: [0 to 2¹⁶ - 1], Default: 0 maxY – Type: uint16, Range: [0 to 2¹⁶ - 1], Default: 0
Returns:	err – Type: error

Sets the thresholds for the AnalogValueReachedCallback 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 following constants are available for this function:

For option:

joystick_bricklet.ThresholdOptionOff = 'x'
joystick_bricklet.ThresholdOptionOutside = 'o'
joystick_bricklet.ThresholdOptionInside = 'i'
joystick_bricklet.ThresholdOptionSmaller = '<'
joystick_bricklet.ThresholdOptionGreater = '>'

func (*JoystickBricklet) GetAnalogValueCallbackThreshold() (option rune, minX uint16, maxX uint16, minY uint16, maxY uint16, err error)¶

Returns:	option – Type: rune, Range: See constants, Default: 'x' minX – Type: uint16, Range: [0 to 2¹⁶ - 1], Default: 0 maxX – Type: uint16, Range: [0 to 2¹⁶ - 1], Default: 0 minY – Type: uint16, Range: [0 to 2¹⁶ - 1], Default: 0 maxY – Type: uint16, Range: [0 to 2¹⁶ - 1], Default: 0 err – Type: error

Returns the threshold as set by SetAnalogValueCallbackThreshold().

The following constants are available for this function:

For option:

joystick_bricklet.ThresholdOptionOff = 'x'
joystick_bricklet.ThresholdOptionOutside = 'o'
joystick_bricklet.ThresholdOptionInside = 'i'
joystick_bricklet.ThresholdOptionSmaller = '<'
joystick_bricklet.ThresholdOptionGreater = '>'

func (*JoystickBricklet) SetDebouncePeriod(debounce uint32) (err error)¶

Parameters:	debounce – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 100
Returns:	err – Type: error

Sets the period with which the threshold callbacks

PositionReachedCallback,
AnalogValueReachedCallback

are triggered, if the thresholds

SetPositionCallbackThreshold(),
SetAnalogValueCallbackThreshold()

keep being reached.

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

Returns:	debounce – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 100 err – Type: 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 with the corresponding Deregister*Callback function.

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)¶

Callback Parameters:	x – Type: int16, Range: [-100 to 100] y – Type: int16, Range: [-100 to 100]
Returns:	registrationId – Type: uint64

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

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

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

Callback Parameters:	x – Type: uint16, Range: [0 to 2¹² - 1] y – Type: uint16, Range: [0 to 2¹² - 1]
Returns:	registrationId – Type: uint64

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

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

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

Callback Parameters:	x – Type: int16, Range: [-100 to 100] y – Type: int16, Range: [-100 to 100]
Returns:	registrationId – Type: uint64

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)¶

Callback Parameters:	x – Type: uint16, Range: [0 to 2¹² - 1] y – Type: uint16, Range: [0 to 2¹² - 1]
Returns:	registrationId – Type: uint64

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)¶

Returns:	registrationId – Type: uint64

This callback is triggered when the button is pressed.

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

Returns:	registrationId – Type: uint64

This callback is triggered when the button is released.

Virtual Functions¶

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

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

Returns:	apiVersion – Type: [3]uint8 0: major – Type: uint8, Range: [0 to 255] 1: minor – Type: uint8, Range: [0 to 255] 2: revision – Type: uint8, Range: [0 to 255] err – Type: error

Returns the version of the API definition 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)¶

Parameters:	functionId – Type: uint8, Range: See constants
Returns:	responseExpected – Type: bool err – Type: 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

joystick_bricklet.FunctionCalibrate = 4
joystick_bricklet.FunctionSetPositionCallbackPeriod = 5
joystick_bricklet.FunctionSetAnalogValueCallbackPeriod = 7
joystick_bricklet.FunctionSetPositionCallbackThreshold = 9
joystick_bricklet.FunctionSetAnalogValueCallbackThreshold = 11
joystick_bricklet.FunctionSetDebouncePeriod = 13

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

Parameters:	functionId – Type: uint8, Range: See constants responseExpected – Type: bool
Returns:	err – Type: 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.

The following constants are available for this function:

For functionId:

joystick_bricklet.FunctionCalibrate = 4
joystick_bricklet.FunctionSetPositionCallbackPeriod = 5
joystick_bricklet.FunctionSetAnalogValueCallbackPeriod = 7
joystick_bricklet.FunctionSetPositionCallbackThreshold = 9
joystick_bricklet.FunctionSetAnalogValueCallbackThreshold = 11
joystick_bricklet.FunctionSetDebouncePeriod = 13

func (*JoystickBricklet) SetResponseExpectedAll(responseExpected bool) (err error)¶

Parameters:	responseExpected – Type: bool
Returns:	err – Type: error

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

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.