Go - Current25 Bricklet

This is the description of the Go API bindings for the Current25 Bricklet. General information and technical specifications for the Current25 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/current25_bricklet"
    "github.com/Tinkerforge/go-api-bindings/ipconnection"
)

const ADDR string = "localhost:4223"
const UID string = "XYZ" // Change XYZ to the UID of your Current25 Bricklet.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    c, _ := current25_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 current.
    current, _ := c.GetCurrent()
    fmt.Printf("Current: %f A\n", float64(current)/1000.0)

    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/current25_bricklet"
    "github.com/Tinkerforge/go-api-bindings/ipconnection"
)

const ADDR string = "localhost:4223"
const UID string = "XYZ" // Change XYZ to the UID of your Current25 Bricklet.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    c, _ := current25_bricklet.New(UID, &ipcon) // Create device object.

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

    c.RegisterCurrentCallback(func(current int16) {
        fmt.Printf("Current: %f A\n", float64(current)/1000.0)
    })

    // Set period for current receiver to 1s (1000ms).
    // Note: The current callback is only called every second
    //       if the current has changed since the last call!
    c.SetCurrentCallbackPeriod(1000)

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

Threshold

Download (example_threshold.go)

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package main

import (
    "fmt"
    "github.com/Tinkerforge/go-api-bindings/current25_bricklet"
    "github.com/Tinkerforge/go-api-bindings/ipconnection"
)

const ADDR string = "localhost:4223"
const UID string = "XYZ" // Change XYZ to the UID of your Current25 Bricklet.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    c, _ := current25_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 10 seconds (10000ms).
    c.SetDebouncePeriod(10000)

    c.RegisterCurrentReachedCallback(func(current int16) {
        fmt.Printf("Current: %f A\n", float64(current)/1000.0)
    })

    // Configure threshold for current "greater than 5 A".
    c.SetCurrentCallbackThreshold('>', 5*1000, 0)

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

API

The Current25 Bricklet API is defined in the package github.com/Tinkerforge/go-api-bindings/current25_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 NewCurrent25Bricklet(uid string, ipcon *IPConnection) (device Current25Bricklet, err error)

Creates a new Current25Bricklet 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 (*Current25Bricklet) GetCurrent() (current int16, err error)

Returns the current of the sensor. The value is in mA and between -25000mA and 25000mA.

If you want to get the current periodically, it is recommended to use the RegisterCurrentCallback callback and set the period with SetCurrentCallbackPeriod().

Advanced Functions

func (*Current25Bricklet) Calibrate() (err error)

Calibrates the 0 value of the sensor. You have to call this function when there is no current present.

The zero point of the current sensor is depending on the exact properties of the analog-to-digital converter, the length of the Bricklet cable and the temperature. Thus, if you change the Brick or the environment in which the Bricklet is used, you might have to recalibrate.

The resulting calibration will be saved on the EEPROM of the Current Bricklet.

func (*Current25Bricklet) IsOverCurrent() (over bool, err error)

Returns true if more than 25A were measured.

Note

To reset this value you have to power cycle the Bricklet.

func (*Current25Bricklet) GetAnalogValue() (value uint16, err error)

Returns the value as read by a 12-bit analog-to-digital converter. The value is between 0 and 4095.

Note

The value returned by GetCurrent() 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 RegisterAnalogValueCallback callback and set the period with SetAnalogValueCallbackPeriod().

func (*Current25Bricklet) 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 (*Current25Bricklet) 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 (*Current25Bricklet) 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 = 2
  • FunctionSetCurrentCallbackPeriod = 5
  • FunctionSetAnalogValueCallbackPeriod = 7
  • FunctionSetCurrentCallbackThreshold = 9
  • FunctionSetAnalogValueCallbackThreshold = 11
  • FunctionSetDebouncePeriod = 13
func (*Current25Bricklet) SetResponseExpectedAll(responseExpected bool) (err error)

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

func (*Current25Bricklet) 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 (*Current25Bricklet) SetCurrentCallbackPeriod(period uint32) (err error)

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

The RegisterCurrentCallback callback is only triggered if the current has changed since the last triggering.

The default value is 0.

func (*Current25Bricklet) GetCurrentCallbackPeriod() (period uint32, err error)

Returns the period as set by SetCurrentCallbackPeriod().

func (*Current25Bricklet) 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 value has changed since the last triggering.

The default value is 0.

func (*Current25Bricklet) GetAnalogValueCallbackPeriod() (period uint32, err error)

Returns the period as set by SetAnalogValueCallbackPeriod().

func (*Current25Bricklet) SetCurrentCallbackThreshold(option ThresholdOption, min int16, max int16) (err error)

Sets the thresholds for the RegisterCurrentReachedCallback callback.

The following options are possible:

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

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

The following constants are available for this function:

  • ThresholdOptionOff = 'x'
  • ThresholdOptionOutside = 'o'
  • ThresholdOptionInside = 'i'
  • ThresholdOptionSmaller = '<'
  • ThresholdOptionGreater = '>'
func (*Current25Bricklet) GetCurrentCallbackThreshold() (option ThresholdOption, min int16, max int16, err error)

Returns the threshold as set by SetCurrentCallbackThreshold().

The following constants are available for this function:

  • ThresholdOptionOff = 'x'
  • ThresholdOptionOutside = 'o'
  • ThresholdOptionInside = 'i'
  • ThresholdOptionSmaller = '<'
  • ThresholdOptionGreater = '>'
func (*Current25Bricklet) SetAnalogValueCallbackThreshold(option ThresholdOption, min uint16, max 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 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 default value is ('x', 0, 0).

The following constants are available for this function:

  • ThresholdOptionOff = 'x'
  • ThresholdOptionOutside = 'o'
  • ThresholdOptionInside = 'i'
  • ThresholdOptionSmaller = '<'
  • ThresholdOptionGreater = '>'
func (*Current25Bricklet) GetAnalogValueCallbackThreshold() (option ThresholdOption, min uint16, max 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 (*Current25Bricklet) 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 (*Current25Bricklet) 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 (*Current25Bricklet) RegisterCurrentCallback(func(current int16)) (registrationId uint64)

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

This callback is triggered periodically with the period that is set by SetCurrentCallbackPeriod(). The callback parameter is the current of the sensor.

The RegisterCurrentCallback callback is only triggered if the current has changed since the last triggering.

func (*Current25Bricklet) RegisterAnalogValueCallback(func(value 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 parameter is the analog value of the sensor.

The RegisterAnalogValueCallback callback is only triggered if the current has changed since the last triggering.

func (*Current25Bricklet) RegisterCurrentReachedCallback(func(current int16)) (registrationId uint64)

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

This callback is triggered when the threshold as set by SetCurrentCallbackThreshold() is reached. The callback parameter is the current of the sensor.

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

func (*Current25Bricklet) RegisterAnalogValueReachedCallback(func(value 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 parameter is the analog value of the sensor.

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

func (*Current25Bricklet) RegisterOverCurrentCallback(func()) (registrationId uint64)

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

This callback is triggered when an over current is measured (see IsOverCurrent()).

Constants

current25_bricklet.DeviceIdentifier

This constant is used to identify a Current25 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.

current25_bricklet.DeviceDisplayName

This constant represents the human readable name of a Current25 Bricklet.