Go - Rotary Encoder Bricklet

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

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
package main

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

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

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    re, _ := rotary_encoder_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 count without reset.
    count, _ := re.GetCount(false)
    fmt.Printf("Count: \n", count)

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

Callback

Download (example_callback.go)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
package main

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

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

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

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

    re.RegisterCountCallback(func(count int32) {
        fmt.Printf("Count: %d\n", count)
    })

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

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

API

The Rotary Encoder Bricklet API is defined in the package github.com/Tinkerforge/go-api-bindings/rotary_encoder_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 rotary_encoder_bricklet.New(uid string, ipcon *IPConnection) (device RotaryEncoderBricklet, err error)
Parameters:
  • uid – Type: string
  • ipcon – Type: *IPConnection
Returns:
  • device – Type: RotaryEncoderBricklet
  • err – Type: error

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

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

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

func (*RotaryEncoderBricklet) GetCount(reset bool) (count int32, err error)
Parameters:
  • reset – Type: bool
Returns:
  • count – Type: int32, Range: [-231 to 231 - 1]
  • err – Type: error

Returns the current count of the encoder. If you set reset to true, the count is set back to 0 directly after the current count is read.

The encoder has 24 steps per rotation

Turning the encoder to the left decrements the counter, so a negative count is possible.

func (*RotaryEncoderBricklet) 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 RegisterPressedCallback and RegisterReleasedCallback callbacks to handle the button.

Advanced Functions

func (*RotaryEncoderBricklet) 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', 'i', '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). The Raspberry Pi HAT (Zero) Brick is always at position 'i' and the Bricklet connected to an Isolator Bricklet is always as 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 (*RotaryEncoderBricklet) SetCountCallbackPeriod(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 RegisterCountCallback callback is triggered periodically. A value of 0 turns the callback off.

The RegisterCountCallback callback is only triggered if the count has changed since the last triggering.

func (*RotaryEncoderBricklet) GetCountCallbackPeriod() (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 SetCountCallbackPeriod().

func (*RotaryEncoderBricklet) SetCountCallbackThreshold(option rune, min int32, max int32) (err error)
Parameters:
  • option – Type: rune, Range: See constants, Default: 'x'
  • min – Type: int32, Range: [-231 to 231 - 1], Default: 0
  • max – Type: int32, Range: [-231 to 231 - 1], Default: 0
Returns:
  • err – Type: error

Sets the thresholds for the RegisterCountReachedCallback callback.

The following options are possible:

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

The following constants are available for this function:

For option:

  • rotary_encoder_bricklet.ThresholdOptionOff = 'x'
  • rotary_encoder_bricklet.ThresholdOptionOutside = 'o'
  • rotary_encoder_bricklet.ThresholdOptionInside = 'i'
  • rotary_encoder_bricklet.ThresholdOptionSmaller = '<'
  • rotary_encoder_bricklet.ThresholdOptionGreater = '>'
func (*RotaryEncoderBricklet) GetCountCallbackThreshold() (option rune, min int32, max int32, err error)
Returns:
  • option – Type: rune, Range: See constants, Default: 'x'
  • min – Type: int32, Range: [-231 to 231 - 1], Default: 0
  • max – Type: int32, Range: [-231 to 231 - 1], Default: 0
  • err – Type: error

Returns the threshold as set by SetCountCallbackThreshold().

The following constants are available for this function:

For option:

  • rotary_encoder_bricklet.ThresholdOptionOff = 'x'
  • rotary_encoder_bricklet.ThresholdOptionOutside = 'o'
  • rotary_encoder_bricklet.ThresholdOptionInside = 'i'
  • rotary_encoder_bricklet.ThresholdOptionSmaller = '<'
  • rotary_encoder_bricklet.ThresholdOptionGreater = '>'
func (*RotaryEncoderBricklet) 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 callback

is triggered, if the thresholds

keeps being reached.

func (*RotaryEncoderBricklet) 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 (*RotaryEncoderBricklet) RegisterCountCallback(func(count int32)) (registrationId uint64)
Callback Parameters:
  • count – Type: int32, Range: [-231 to 231 - 1]
Returns:
  • registrationId – Type: uint64

This callback is triggered periodically with the period that is set by SetCountCallbackPeriod(). The callback parameter is the count of the encoder.

The RegisterCountCallback callback is only triggered if the count has changed since the last triggering.

func (*RotaryEncoderBricklet) RegisterCountReachedCallback(func(count int32)) (registrationId uint64)
Callback Parameters:
  • count – Type: int32, Range: [-231 to 231 - 1]
Returns:
  • registrationId – Type: uint64

This callback is triggered when the threshold as set by SetCountCallbackThreshold() is reached. The callback parameter is the count of the encoder.

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

func (*RotaryEncoderBricklet) RegisterPressedCallback(func()) (registrationId uint64)
Returns:
  • registrationId – Type: uint64

This callback is triggered when the button is pressed.

func (*RotaryEncoderBricklet) 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 (*RotaryEncoderBricklet) 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 (*RotaryEncoderBricklet) 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:

  • rotary_encoder_bricklet.FunctionSetCountCallbackPeriod = 2
  • rotary_encoder_bricklet.FunctionSetCountCallbackThreshold = 4
  • rotary_encoder_bricklet.FunctionSetDebouncePeriod = 6
func (*RotaryEncoderBricklet) 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:

  • rotary_encoder_bricklet.FunctionSetCountCallbackPeriod = 2
  • rotary_encoder_bricklet.FunctionSetCountCallbackThreshold = 4
  • rotary_encoder_bricklet.FunctionSetDebouncePeriod = 6
func (*RotaryEncoderBricklet) 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

rotary_encoder_bricklet.DeviceIdentifier

This constant is used to identify a Rotary Encoder 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.

rotary_encoder_bricklet.DeviceDisplayName

This constant represents the human readable name of a Rotary Encoder Bricklet.