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Software / API Bindings / Go / API Reference and Examples / Bricklets / Linear Poti Bricklet

Go - Linear Poti Bricklet

This is the description of the Go API bindings for the Linear Poti Bricklet. General information and technical specifications for the Linear Poti 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/linear_poti_bricklet"
)

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

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    lp, _ := linear_poti_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.
    position, _ := lp.GetPosition()
    fmt.Printf("Position: %d %%\n", position) // Range: 0 to 100

    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/linear_poti_bricklet"
)

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

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

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

    lp.RegisterPositionCallback(func(position uint16) {
        fmt.Printf("Position: %d %%\n", position) // Range: 0 to 100
    })

    // Set period for position receiver to 0.05s (50ms).
    // Note: The position callback is only called every 0.05 seconds
    //       if the position has changed since the last call!
    lp.SetPositionCallbackPeriod(50)

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

API

The Linear Poti Bricklet API is defined in the package github.com/Tinkerforge/go-api-bindings/linear_poti_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 linear_poti_bricklet.New(uid string, ipcon *IPConnection) (device LinearPotiBricklet, err error)
Parameters:
  • uid – Type: string
  • ipcon – Type: *IPConnection
Returns:
  • device – Type: LinearPotiBricklet
  • err – Type: error

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

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

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

func (*LinearPotiBricklet) GetPosition() (position uint16, err error)
Returns:
  • position – Type: uint16, Unit: 1 %, Range: [0 to 100]
  • err – Type: error

Returns the position of the linear potentiometer. The value is between 0% (slider down) and 100% (slider up).

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

Advanced Functions

func (*LinearPotiBricklet) GetAnalogValue() (value uint16, err error)
Returns:
  • value – Type: uint16, Range: [0 to 212 - 1]
  • err – Type: error

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

Note

The value returned by GetPosition() is 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 value periodically, it is recommended to use the AnalogValueCallback callback and set the period with SetAnalogValueCallbackPeriod().

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

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 (*LinearPotiBricklet) 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 (*LinearPotiBricklet) 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 (*LinearPotiBricklet) 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 value has changed since the last triggering.

func (*LinearPotiBricklet) 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 (*LinearPotiBricklet) SetPositionCallbackThreshold(option rune, min uint16, max uint16) (err error)
Parameters:
  • option – Type: rune, Range: See constants, Default: 'x'
  • min – Type: uint16, Unit: 1 %, Range: [0 to 216 - 1], Default: 0
  • max – Type: uint16, Unit: 1 %, Range: [0 to 216 - 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 value (max is ignored)
'>' Callback is triggered when the position is greater than the min value (max is ignored)

The following constants are available for this function:

For option:

  • linear_poti_bricklet.ThresholdOptionOff = 'x'
  • linear_poti_bricklet.ThresholdOptionOutside = 'o'
  • linear_poti_bricklet.ThresholdOptionInside = 'i'
  • linear_poti_bricklet.ThresholdOptionSmaller = '<'
  • linear_poti_bricklet.ThresholdOptionGreater = '>'
func (*LinearPotiBricklet) GetPositionCallbackThreshold() (option rune, min uint16, max uint16, err error)
Returns:
  • option – Type: rune, Range: See constants, Default: 'x'
  • min – Type: uint16, Unit: 1 %, Range: [0 to 216 - 1], Default: 0
  • max – Type: uint16, Unit: 1 %, Range: [0 to 216 - 1], Default: 0
  • err – Type: error

Returns the threshold as set by SetPositionCallbackThreshold().

The following constants are available for this function:

For option:

  • linear_poti_bricklet.ThresholdOptionOff = 'x'
  • linear_poti_bricklet.ThresholdOptionOutside = 'o'
  • linear_poti_bricklet.ThresholdOptionInside = 'i'
  • linear_poti_bricklet.ThresholdOptionSmaller = '<'
  • linear_poti_bricklet.ThresholdOptionGreater = '>'
func (*LinearPotiBricklet) SetAnalogValueCallbackThreshold(option rune, min uint16, max uint16) (err error)
Parameters:
  • option – Type: rune, Range: See constants, Default: 'x'
  • min – Type: uint16, Range: [0 to 216 - 1], Default: 0
  • max – 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 value is outside the min and max values
'i' Callback is triggered when the analog value is inside the min and max values
'<' Callback is triggered when the analog value is smaller than the min value (max is ignored)
'>' Callback is triggered when the analog value is greater than the min value (max is ignored)

The following constants are available for this function:

For option:

  • linear_poti_bricklet.ThresholdOptionOff = 'x'
  • linear_poti_bricklet.ThresholdOptionOutside = 'o'
  • linear_poti_bricklet.ThresholdOptionInside = 'i'
  • linear_poti_bricklet.ThresholdOptionSmaller = '<'
  • linear_poti_bricklet.ThresholdOptionGreater = '>'
func (*LinearPotiBricklet) GetAnalogValueCallbackThreshold() (option rune, min uint16, max uint16, err error)
Returns:
  • option – Type: rune, Range: See constants, Default: 'x'
  • min – Type: uint16, Range: [0 to 216 - 1], Default: 0
  • max – 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:

  • linear_poti_bricklet.ThresholdOptionOff = 'x'
  • linear_poti_bricklet.ThresholdOptionOutside = 'o'
  • linear_poti_bricklet.ThresholdOptionInside = 'i'
  • linear_poti_bricklet.ThresholdOptionSmaller = '<'
  • linear_poti_bricklet.ThresholdOptionGreater = '>'
func (*LinearPotiBricklet) 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

are triggered, if the thresholds

keep being reached.

func (*LinearPotiBricklet) 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 (*LinearPotiBricklet) RegisterPositionCallback(func(position uint16)) (registrationId uint64)
Callback Parameters:
  • position – Type: uint16, Unit: 1 %, Range: [0 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 linear potentiometer.

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

func (*LinearPotiBricklet) RegisterAnalogValueCallback(func(value uint16)) (registrationId uint64)
Callback Parameters:
  • value – 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 parameter is the analog value of the Linear Potentiometer.

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

func (*LinearPotiBricklet) RegisterPositionReachedCallback(func(position uint16)) (registrationId uint64)
Callback Parameters:
  • position – Type: uint16, Unit: 1 %, Range: [0 to 100]
Returns:
  • registrationId – Type: uint64

This callback is triggered when the threshold as set by SetPositionCallbackThreshold() is reached. The callback parameter is the position of the linear potentiometer.

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

func (*LinearPotiBricklet) RegisterAnalogValueReachedCallback(func(value uint16)) (registrationId uint64)
Callback Parameters:
  • value – 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 parameter is the analog value of the linear potentiometer.

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

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 (*LinearPotiBricklet) 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 (*LinearPotiBricklet) 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:

  • linear_poti_bricklet.FunctionSetPositionCallbackPeriod = 3
  • linear_poti_bricklet.FunctionSetAnalogValueCallbackPeriod = 5
  • linear_poti_bricklet.FunctionSetPositionCallbackThreshold = 7
  • linear_poti_bricklet.FunctionSetAnalogValueCallbackThreshold = 9
  • linear_poti_bricklet.FunctionSetDebouncePeriod = 11
func (*LinearPotiBricklet) 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.

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:

  • linear_poti_bricklet.FunctionSetPositionCallbackPeriod = 3
  • linear_poti_bricklet.FunctionSetAnalogValueCallbackPeriod = 5
  • linear_poti_bricklet.FunctionSetPositionCallbackThreshold = 7
  • linear_poti_bricklet.FunctionSetAnalogValueCallbackThreshold = 9
  • linear_poti_bricklet.FunctionSetDebouncePeriod = 11
func (*LinearPotiBricklet) 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

linear_poti_bricklet.DeviceIdentifier

This constant is used to identify a Linear Poti 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.

linear_poti_bricklet.DeviceDisplayName

This constant represents the human readable name of a Linear Poti Bricklet.