Go - CAN Bricklet 2.0¶

Loopback¶

Download (example_loopback.go)

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package main

import (
    "fmt"
    "github.com/Tinkerforge/go-api-bindings/can_v2_bricklet"
    "github.com/Tinkerforge/go-api-bindings/ipconnection"
)

const ADDR string = "localhost:4223"
const UID string = "XYZ" // Change XYZ to the UID of your CAN Bricklet 2.0.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    can, _ := can_v2_bricklet.New(UID, &ipcon) // Create device object.

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

    // Configure transceiver for loopback mode
    can.SetTransceiverConfiguration(1000000, 625,
        can_v2_bricklet.TransceiverModeLoopback)

    can.RegisterFrameReadCallback(func(frameType can_v2_bricklet.FrameType, identifier uint32, data []uint8) {
        if frameType == can_v2_bricklet.FrameTypeStandardData {
            fmt.Println("Frame Type: Standard Data")
        } else if frameType == can_v2_bricklet.FrameTypeStandardRemote {
            fmt.Println("Frame Type: Standard Remote")
        } else if frameType == can_v2_bricklet.FrameTypeExtendedData {
            fmt.Println("Frame Type: Extended Data")
        } else if frameType == can_v2_bricklet.FrameTypeExtendedRemote {
            fmt.Println("Frame Type: Extended Remote")
        }

        fmt.Printf("Identifier: %d\n", identifier)
        fmt.Printf("Data (Length: %d)\n:", len(data))

        for _, item := range data {
            fmt.Printf(" %d", item)
        }

        fmt.Println()
        fmt.Println()
    })

    // Enable frame read callback
    can.SetFrameReadCallbackConfiguration(true)

    // Write standard data frame with identifier 1742 and 3 bytes of data
    can.WriteFrame(can_v2_bricklet.FrameTypeStandardData, 1742, []uint8{42, 23, 17})

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

    can.SetFrameReadCallbackConfiguration(false)
}

Basic Functions¶

func can_v2_bricklet.New(uid string, ipcon *IPConnection) (device CANV2Bricklet, err error)¶

Parameters:	uid – Type: string ipcon – Type: *IPConnection
Returns:	device – Type: CANV2Bricklet err – Type: error

Creates a new CANV2Bricklet object with the unique device ID uid and adds it to the IPConnection ipcon:

device, err := can_v2_bricklet.New("YOUR_DEVICE_UID", &ipcon)

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

func (*CANV2Bricklet) WriteFrame(frameType uint8, identifier uint32, data []uint8) (success bool, err error)¶

Parameters:	frameType – Type: uint8, Range: See constants identifier – Type: uint32, Range: [0 to 230 - 1] data – Type: []uint8, Length: variable, Range: [0 to 255]
Returns:	success – Type: bool err – Type: error

Writes a data or remote frame to the write queue to be transmitted over the CAN transceiver.

The Bricklet supports the standard 11-bit (CAN 2.0A) and the additional extended 29-bit (CAN 2.0B) identifiers. For standard frames the Bricklet uses bit 0 to 10 from the identifier parameter as standard 11-bit identifier. For extended frames the Bricklet uses bit 0 to 28 from the identifier parameter as extended 29-bit identifier.

The data parameter can be up to 15 bytes long. For data frames up to 8 bytes will be used as the actual data. The length (DLC) field in the data or remote frame will be set to the actual length of the data parameter. This allows to transmit data and remote frames with excess length. For remote frames only the length of the data parameter is used. The actual data bytes are ignored.

Returns true if the frame was successfully added to the write queue. Returns false if the frame could not be added because write queue is already full or because the write buffer or the write backlog are configured with a size of zero (see SetQueueConfiguration()).

The write queue can overflow if frames are written to it at a higher rate than the Bricklet can transmitted them over the CAN transceiver. This may happen if the CAN transceiver is configured as read-only or is using a low baud rate (see SetTransceiverConfiguration()). It can also happen if the CAN bus is congested and the frame cannot be transmitted because it constantly loses arbitration or because the CAN transceiver is currently disabled due to a high write error level (see GetErrorLog()).

The following constants are available for this function:

For frameType:

• can_v2_bricklet.FrameTypeStandardData = 0
• can_v2_bricklet.FrameTypeStandardRemote = 1
• can_v2_bricklet.FrameTypeExtendedData = 2
• can_v2_bricklet.FrameTypeExtendedRemote = 3

func (*CANV2Bricklet) ReadFrame() (data []uint8, success bool, frameType uint8, identifier uint32, err error)¶

Returns:	success – Type: bool frameType – Type: uint8, Range: See constants identifier – Type: uint32, Range: [0 to 230 - 1] data – Type: []uint8, Length: variable, Range: [0 to 255] err – Type: error

Tries to read the next data or remote frame from the read queue and returns it. If a frame was successfully read, then the success return value is set to true and the other return values contain the frame. If the read queue is empty and no frame could be read, then the success return value is set to false and the other return values contain invalid data.

The identifier return value follows the identifier format described for WriteFrame().

The data return value can be up to 15 bytes long. For data frames up to the first 8 bytes are the actual received data. All bytes after the 8th byte are always zero and only there to indicate the length of a data or remote frame with excess length. For remote frames the length of the data return value represents the requested length. The actual data bytes are always zero.

A configurable read filter can be used to define which frames should be received by the CAN transceiver and put into the read queue (see SetReadFilterConfiguration()).

Instead of polling with this function, you can also use callbacks. See the SetFrameReadCallbackConfiguration() function and the FrameReadCallback callback.

The following constants are available for this function:

For frameType:

• can_v2_bricklet.FrameTypeStandardData = 0
• can_v2_bricklet.FrameTypeStandardRemote = 1
• can_v2_bricklet.FrameTypeExtendedData = 2
• can_v2_bricklet.FrameTypeExtendedRemote = 3

func (*CANV2Bricklet) SetTransceiverConfiguration(baudRate uint32, samplePoint uint16, transceiverMode uint8) (err error)¶

Parameters:	baudRate – Type: uint32, Unit: 1 bit/s, Range: [10000 to 1000000], Default: 125000 samplePoint – Type: uint16, Unit: 1/10 %, Range: [500 to 900], Default: 625 transceiverMode – Type: uint8, Range: See constants, Default: 0
Returns:	err – Type: error

Sets the transceiver configuration for the CAN bus communication.

The CAN transceiver has three different modes:

• Normal: Reads from and writes to the CAN bus and performs active bus error detection and acknowledgement.
• Loopback: All reads and writes are performed internally. The transceiver is disconnected from the actual CAN bus.
• Read-Only: Only reads from the CAN bus, but does neither active bus error detection nor acknowledgement. Only the receiving part of the transceiver is connected to the CAN bus.

The following constants are available for this function:

For transceiverMode:

• can_v2_bricklet.TransceiverModeNormal = 0
• can_v2_bricklet.TransceiverModeLoopback = 1
• can_v2_bricklet.TransceiverModeReadOnly = 2

func (*CANV2Bricklet) GetTransceiverConfiguration() (baudRate uint32, samplePoint uint16, transceiverMode uint8, err error)¶

Returns:	baudRate – Type: uint32, Unit: 1 bit/s, Range: [10000 to 1000000], Default: 125000 samplePoint – Type: uint16, Unit: 1/10 %, Range: [500 to 900], Default: 625 transceiverMode – Type: uint8, Range: See constants, Default: 0 err – Type: error

Returns the configuration as set by SetTransceiverConfiguration().

The following constants are available for this function:

For transceiverMode:

• can_v2_bricklet.TransceiverModeNormal = 0
• can_v2_bricklet.TransceiverModeLoopback = 1
• can_v2_bricklet.TransceiverModeReadOnly = 2

Advanced Functions¶

func (*CANV2Bricklet) SetQueueConfiguration(writeBufferSize uint8, writeBufferTimeout int32, writeBacklogSize uint16, readBufferSizes []int8, readBacklogSize uint16) (err error)¶

Parameters:	writeBufferSize – Type: uint8, Range: [0 to 32], Default: 8 writeBufferTimeout – Type: int32, Range: [-1 to 231 - 1], Default: 0 writeBacklogSize – Type: uint16, Range: [0 to 768], Default: 383 readBufferSizes – Type: []int8, Length: variable, Range: [-32 to -1, 1 to 32], Default: {16, -8} readBacklogSize – Type: uint16, Range: [0 to 768], Default: 383
Returns:	err – Type: error

Sets the write and read queue configuration.

The CAN transceiver has 32 buffers in total in hardware for transmitting and receiving frames. Additionally, the Bricklet has a backlog for 768 frames in total in software. The buffers and the backlog can be freely assigned to the write and read queues.

WriteFrame() writes a frame into the write backlog. The Bricklet moves the frame from the backlog into a free write buffer. The CAN transceiver then transmits the frame from the write buffer to the CAN bus. If there are no write buffers (write_buffer_size is zero) or there is no write backlog (write_backlog_size is zero) then no frames can be transmitted and WriteFrame() returns always false.

The CAN transceiver receives a frame from the CAN bus and stores it into a free read buffer. The Bricklet moves the frame from the read buffer into the read backlog. ReadFrame() reads the frame from the read backlog and returns it. If there are no read buffers (read_buffer_sizes is empty) or there is no read backlog (read_backlog_size is zero) then no frames can be received and ReadFrame() returns always false.

There can be multiple read buffers, because the CAN transceiver cannot receive data and remote frames into the same read buffer. A positive read buffer size represents a data frame read buffer and a negative read buffer size represents a remote frame read buffer. A read buffer size of zero is not allowed. By default the first read buffer is configured for data frames and the second read buffer is configured for remote frame. There can be up to 32 different read buffers, assuming that no write buffer is used. Each read buffer has its own filter configuration (see SetReadFilterConfiguration()).

A valid queue configuration fulfills these conditions:

write_buffer_size + abs(read_buffer_size_0) + abs(read_buffer_size_1) + ... + abs(read_buffer_size_31) <= 32
write_backlog_size + read_backlog_size <= 768

The write buffer timeout has three different modes that define how a failed frame transmission should be handled:

• Single-Shot (< 0): Only one transmission attempt will be made. If the transmission fails then the frame is discarded.
• Infinite (= 0): Infinite transmission attempts will be made. The frame will never be discarded.
• Milliseconds (> 0): A limited number of transmission attempts will be made. If the frame could not be transmitted successfully after the configured number of milliseconds then the frame is discarded.

The current content of the queues is lost when this function is called.

func (*CANV2Bricklet) GetQueueConfiguration() (readBufferSizes []int8, writeBufferSize uint8, writeBufferTimeout int32, writeBacklogSize uint16, readBacklogSize uint16, err error)¶

Returns:	writeBufferSize – Type: uint8, Range: [0 to 32], Default: 8 writeBufferTimeout – Type: int32, Range: [-1 to 231 - 1], Default: 0 writeBacklogSize – Type: uint16, Range: [0 to 768], Default: 383 readBufferSizes – Type: []int8, Length: variable, Range: [-32 to -1, 1 to 32], Default: {16, -8} readBacklogSize – Type: uint16, Range: [0 to 768], Default: 383 err – Type: error

Returns the queue configuration as set by SetQueueConfiguration().

func (*CANV2Bricklet) SetReadFilterConfiguration(bufferIndex uint8, filterMode uint8, filterMask uint32, filterIdentifier uint32) (err error)¶

Parameters:	bufferIndex – Type: uint8, Range: [0 to 31] filterMode – Type: uint8, Range: See constants, Default: 0 filterMask – Type: uint32, Range: [0 to 230 - 1] filterIdentifier – Type: uint32, Range: [0 to 230 - 1]
Returns:	err – Type: error

Set the read filter configuration for the given read buffer index. This can be used to define which frames should be received by the CAN transceiver and put into the read buffer.

The read filter has four different modes that define if and how the filter mask and the filter identifier are applied:

• Accept-All: All frames are received.
• Match-Standard-Only: Only standard frames with a matching identifier are received.
• Match-Extended-Only: Only extended frames with a matching identifier are received.
• Match-Standard-And-Extended: Standard and extended frames with a matching identifier are received.

The filter mask and filter identifier are used as bit masks. Their usage depends on the mode:

• Accept-All: Mask and identifier are ignored.
• Match-Standard-Only: Bit 0 to 10 (11 bits) of filter mask and filter identifier are used to match the 11-bit identifier of standard frames.
• Match-Extended-Only: Bit 0 to 28 (29 bits) of filter mask and filter identifier are used to match the 29-bit identifier of extended frames.
• Match-Standard-And-Extended: Bit 18 to 28 (11 bits) of filter mask and filter identifier are used to match the 11-bit identifier of standard frames, bit 0 to 17 (18 bits) are ignored in this case. Bit 0 to 28 (29 bits) of filter mask and filter identifier are used to match the 29-bit identifier of extended frames.

The filter mask and filter identifier are applied in this way: The filter mask is used to select the frame identifier bits that should be compared to the corresponding filter identifier bits. All unselected bits are automatically accepted. All selected bits have to match the filter identifier to be accepted. If all bits for the selected mode are accepted then the frame is accepted and is added to the read buffer.

Filter Mask Bit	Filter Identifier Bit	Frame Identifier Bit	Result
0	X	X	Accept
1	0	0	Accept
1	0	1	Reject
1	1	0	Reject
1	1	1	Accept

For example, to receive standard frames with identifier 0x123 only, the mode can be set to Match-Standard-Only with 0x7FF as mask and 0x123 as identifier. The mask of 0x7FF selects all 11 identifier bits for matching so that the identifier has to be exactly 0x123 to be accepted.

To accept identifier 0x123 and identifier 0x456 at the same time, just set filter 2 to 0x456 and keep mask and filter 1 unchanged.

There can be up to 32 different read filters configured at the same time, because there can be up to 32 read buffer (see SetQueueConfiguration()).

The default mode is accept-all for all read buffers.

The following constants are available for this function:

For filterMode:

• can_v2_bricklet.FilterModeAcceptAll = 0
• can_v2_bricklet.FilterModeMatchStandardOnly = 1
• can_v2_bricklet.FilterModeMatchExtendedOnly = 2
• can_v2_bricklet.FilterModeMatchStandardAndExtended = 3

func (*CANV2Bricklet) GetReadFilterConfiguration(bufferIndex uint8) (filterMode uint8, filterMask uint32, filterIdentifier uint32, err error)¶

Parameters:	bufferIndex – Type: uint8, Range: [0 to 31]
Returns:	filterMode – Type: uint8, Range: See constants, Default: 0 filterMask – Type: uint32, Range: [0 to 230 - 1] filterIdentifier – Type: uint32, Range: [0 to 230 - 1] err – Type: error

Returns the read filter configuration as set by SetReadFilterConfiguration().

The following constants are available for this function:

For filterMode:

• can_v2_bricklet.FilterModeAcceptAll = 0
• can_v2_bricklet.FilterModeMatchStandardOnly = 1
• can_v2_bricklet.FilterModeMatchExtendedOnly = 2
• can_v2_bricklet.FilterModeMatchStandardAndExtended = 3

func (*CANV2Bricklet) GetErrorLog() (readBufferOverflowErrorOccurred []bool, transceiverState uint8, transceiverWriteErrorLevel uint8, transceiverReadErrorLevel uint8, transceiverStuffingErrorCount uint32, transceiverFormatErrorCount uint32, transceiverACKErrorCount uint32, transceiverBit1ErrorCount uint32, transceiverBit0ErrorCount uint32, transceiverCRCErrorCount uint32, writeBufferTimeoutErrorCount uint32, readBufferOverflowErrorCount uint32, readBacklogOverflowErrorCount uint32, err error)¶

Returns:

transceiverState – Type: uint8, Range: See constants transceiverWriteErrorLevel – Type: uint8, Range: [0 to 255] transceiverReadErrorLevel – Type: uint8, Range: [0 to 255] transceiverStuffingErrorCount – Type: uint32, Range: [0 to 232 - 1] transceiverFormatErrorCount – Type: uint32, Range: [0 to 232 - 1] transceiverACKErrorCount – Type: uint32, Range: [0 to 232 - 1] transceiverBit1ErrorCount – Type: uint32, Range: [0 to 232 - 1] transceiverBit0ErrorCount – Type: uint32, Range: [0 to 232 - 1] transceiverCRCErrorCount – Type: uint32, Range: [0 to 232 - 1] writeBufferTimeoutErrorCount – Type: uint32, Range: [0 to 232 - 1] readBufferOverflowErrorCount – Type: uint32, Range: [0 to 232 - 1] readBufferOverflowErrorOccurred – Type: []bool, Length: variable readBacklogOverflowErrorCount – Type: uint32, Range: [0 to 232 - 1] err – Type: error

Returns information about different kinds of errors.

The write and read error levels indicate the current level of stuffing, form, acknowledgement, bit and checksum errors during CAN bus write and read operations. For each of this error kinds there is also an individual counter.

When the write error level extends 255 then the CAN transceiver gets disabled and no frames can be transmitted or received anymore. The CAN transceiver will automatically be activated again after the CAN bus is idle for a while.

The write buffer timeout, read buffer and backlog overflow counts represents the number of these errors:

• A write buffer timeout occurs if a frame could not be transmitted before the configured write buffer timeout expired (see SetQueueConfiguration()).
• A read buffer overflow occurs if a read buffer of the CAN transceiver still contains the last received frame when the next frame arrives. In this case the last received frame is lost. This happens if the CAN transceiver receives more frames than the Bricklet can handle. Using the read filter (see SetReadFilterConfiguration()) can help to reduce the amount of received frames. This count is not exact, but a lower bound, because the Bricklet might not able detect all overflows if they occur in rapid succession.
• A read backlog overflow occurs if the read backlog of the Bricklet is already full when the next frame should be read from a read buffer of the CAN transceiver. In this case the frame in the read buffer is lost. This happens if the CAN transceiver receives more frames to be added to the read backlog than are removed from the read backlog using the ReadFrame() function. Using the FrameReadCallback callback ensures that the read backlog can not overflow.

The read buffer overflow counter counts the overflows of all configured read buffers. Which read buffer exactly suffered from an overflow can be figured out from the read buffer overflow occurrence list (read_buffer_overflow_error_occurred). Reading the error log clears the occurence list.

The following constants are available for this function:

For transceiverState:

• can_v2_bricklet.TransceiverStateActive = 0
• can_v2_bricklet.TransceiverStatePassive = 1
• can_v2_bricklet.TransceiverStateDisabled = 2

func (*CANV2Bricklet) SetCommunicationLEDConfig(config uint8) (err error)¶

Parameters:	config – Type: uint8, Range: See constants, Default: 3
Returns:	err – Type: error

Sets the communication LED configuration. By default the LED shows CAN-Bus traffic, it flickers once for every 40 transmitted or received frames.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is off.

The following constants are available for this function:

For config:

• can_v2_bricklet.CommunicationLEDConfigOff = 0
• can_v2_bricklet.CommunicationLEDConfigOn = 1
• can_v2_bricklet.CommunicationLEDConfigShowHeartbeat = 2
• can_v2_bricklet.CommunicationLEDConfigShowCommunication = 3

func (*CANV2Bricklet) GetCommunicationLEDConfig() (config uint8, err error)¶

Returns:	config – Type: uint8, Range: See constants, Default: 3 err – Type: error

Returns the configuration as set by SetCommunicationLEDConfig()

The following constants are available for this function:

For config:

• can_v2_bricklet.CommunicationLEDConfigOff = 0
• can_v2_bricklet.CommunicationLEDConfigOn = 1
• can_v2_bricklet.CommunicationLEDConfigShowHeartbeat = 2
• can_v2_bricklet.CommunicationLEDConfigShowCommunication = 3

func (*CANV2Bricklet) SetErrorLEDConfig(config uint8) (err error)¶

Parameters:	config – Type: uint8, Range: See constants, Default: 3
Returns:	err – Type: error

Sets the error LED configuration.

By default (show-transceiver-state) the error LED turns on if the CAN transceiver is passive or disabled state (see GetErrorLog()). If the CAN transceiver is in active state the LED turns off.

If the LED is configured as show-error then the error LED turns on if any error occurs. If you call this function with the show-error option again, the LED will turn off until the next error occurs.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is off.

The following constants are available for this function:

For config:

• can_v2_bricklet.ErrorLEDConfigOff = 0
• can_v2_bricklet.ErrorLEDConfigOn = 1
• can_v2_bricklet.ErrorLEDConfigShowHeartbeat = 2
• can_v2_bricklet.ErrorLEDConfigShowTransceiverState = 3
• can_v2_bricklet.ErrorLEDConfigShowError = 4

func (*CANV2Bricklet) GetErrorLEDConfig() (config uint8, err error)¶

Returns:	config – Type: uint8, Range: See constants, Default: 3 err – Type: error

Returns the configuration as set by SetErrorLEDConfig().

The following constants are available for this function:

For config:

• can_v2_bricklet.ErrorLEDConfigOff = 0
• can_v2_bricklet.ErrorLEDConfigOn = 1
• can_v2_bricklet.ErrorLEDConfigShowHeartbeat = 2
• can_v2_bricklet.ErrorLEDConfigShowTransceiverState = 3
• can_v2_bricklet.ErrorLEDConfigShowError = 4

func (*CANV2Bricklet) GetSPITFPErrorCount() (errorCountAckChecksum uint32, errorCountMessageChecksum uint32, errorCountFrame uint32, errorCountOverflow uint32, err error)¶

Returns:	errorCountAckChecksum – Type: uint32, Range: [0 to 232 - 1] errorCountMessageChecksum – Type: uint32, Range: [0 to 232 - 1] errorCountFrame – Type: uint32, Range: [0 to 232 - 1] errorCountOverflow – Type: uint32, Range: [0 to 232 - 1] err – Type: error

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

• ACK checksum errors,
• message checksum errors,
• framing errors and
• overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

func (*CANV2Bricklet) SetStatusLEDConfig(config uint8) (err error)¶

Parameters:	config – Type: uint8, Range: See constants, Default: 3
Returns:	err – Type: error

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

For config:

• can_v2_bricklet.StatusLEDConfigOff = 0
• can_v2_bricklet.StatusLEDConfigOn = 1
• can_v2_bricklet.StatusLEDConfigShowHeartbeat = 2
• can_v2_bricklet.StatusLEDConfigShowStatus = 3

func (*CANV2Bricklet) GetStatusLEDConfig() (config uint8, err error)¶

Returns:	config – Type: uint8, Range: See constants, Default: 3 err – Type: error

Returns the configuration as set by SetStatusLEDConfig()

The following constants are available for this function:

For config:

• can_v2_bricklet.StatusLEDConfigOff = 0
• can_v2_bricklet.StatusLEDConfigOn = 1
• can_v2_bricklet.StatusLEDConfigShowHeartbeat = 2
• can_v2_bricklet.StatusLEDConfigShowStatus = 3

func (*CANV2Bricklet) GetChipTemperature() (temperature int16, err error)¶

Returns:	temperature – Type: int16, Unit: 1 °C, Range: [-215 to 215 - 1] err – Type: error

Returns the temperature as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

func (*CANV2Bricklet) Reset() (err error)¶

Returns:	err – Type: error

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

func (*CANV2Bricklet) 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 (*CANV2Bricklet) SetFrameReadCallbackConfiguration(enabled bool) (err error)¶

Parameters:	enabled – Type: bool, Default: false
Returns:	err – Type: error

Enables and disables the FrameReadCallback callback.

By default the callback is disabled. Enabling this callback will disable the FrameReadableCallback callback.

func (*CANV2Bricklet) GetFrameReadCallbackConfiguration() (enabled bool, err error)¶

Returns:	enabled – Type: bool, Default: false err – Type: error

Returns true if the FrameReadCallback callback is enabled, false otherwise.

func (*CANV2Bricklet) SetFrameReadableCallbackConfiguration(enabled bool) (err error)¶

Parameters:	enabled – Type: bool, Default: false
Returns:	err – Type: error

Enables and disables the FrameReadableCallback callback.

By default the callback is disabled. Enabling this callback will disable the FrameReadCallback callback.

New in version 2.0.3 (Plugin).

func (*CANV2Bricklet) GetFrameReadableCallbackConfiguration() (enabled bool, err error)¶

Returns:	enabled – Type: bool, Default: false err – Type: error

Returns true if the FrameReadableCallback callback is enabled, false otherwise.

New in version 2.0.3 (Plugin).

func (*CANV2Bricklet) SetErrorOccurredCallbackConfiguration(enabled bool) (err error)¶

Parameters:	enabled – Type: bool, Default: false
Returns:	err – Type: error

Enables and disables the ErrorOccurredCallback callback.

By default the callback is disabled.

New in version 2.0.3 (Plugin).

func (*CANV2Bricklet) GetErrorOccurredCallbackConfiguration() (enabled bool, err error)¶

Returns:	enabled – Type: bool, Default: false err – Type: error

Returns true if the ErrorOccurredCallback callback is enabled, false otherwise.

New in version 2.0.3 (Plugin).

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.

func (*CANV2Bricklet) RegisterFrameReadCallback(func(data []uint8, frameType uint8, identifier uint32)) (registrationId uint64)¶

Callback Parameters:	frameType – Type: uint8, Range: See constants identifier – Type: uint32, Range: [0 to 230 - 1] data – Type: []uint8, Length: variable, Range: [0 to 255]
Returns:	registrationId – Type: uint64

This callback is triggered if a data or remote frame was received by the CAN transceiver.

The identifier return value follows the identifier format described for WriteFrame().

For details on the data return value see ReadFrame().

A configurable read filter can be used to define which frames should be received by the CAN transceiver and put into the read queue (see SetReadFilterConfiguration()).

To enable this callback, use SetFrameReadCallbackConfiguration().

Note

If reconstructing the value fails, the callback is triggered with nil for data.

The following constants are available for this function:

For frameType:

• can_v2_bricklet.FrameTypeStandardData = 0
• can_v2_bricklet.FrameTypeStandardRemote = 1
• can_v2_bricklet.FrameTypeExtendedData = 2
• can_v2_bricklet.FrameTypeExtendedRemote = 3

func (*CANV2Bricklet) RegisterFrameReadableCallback(func()) (registrationId uint64)¶

Returns:	registrationId – Type: uint64

This callback is triggered if a data or remote frame was received by the CAN transceiver. The received frame can be read with ReadFrame(). If additional frames are received, but ReadFrame() was not called yet, the callback will not trigger again.

A configurable read filter can be used to define which frames should be received by the CAN transceiver and put into the read queue (see SetReadFilterConfiguration()).

To enable this callback, use SetFrameReadableCallbackConfiguration().

New in version 2.0.3 (Plugin).

func (*CANV2Bricklet) RegisterErrorOccurredCallback(func()) (registrationId uint64)¶

Returns:	registrationId – Type: uint64

This callback is triggered if any error occurred while writing, reading or transmitting CAN frames.

The callback is only triggered once until GetErrorLog() is called. That function will return details abount the error(s) occurred.

To enable this callback, use SetErrorOccurredCallbackConfiguration().

New in version 2.0.3 (Plugin).

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 (*CANV2Bricklet) 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 (*CANV2Bricklet) 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:

• can_v2_bricklet.FunctionSetFrameReadCallbackConfiguration = 3
• can_v2_bricklet.FunctionSetTransceiverConfiguration = 5
• can_v2_bricklet.FunctionSetQueueConfiguration = 7
• can_v2_bricklet.FunctionSetReadFilterConfiguration = 9
• can_v2_bricklet.FunctionSetCommunicationLEDConfig = 12
• can_v2_bricklet.FunctionSetErrorLEDConfig = 14
• can_v2_bricklet.FunctionSetFrameReadableCallbackConfiguration = 17
• can_v2_bricklet.FunctionSetErrorOccurredCallbackConfiguration = 20
• can_v2_bricklet.FunctionSetWriteFirmwarePointer = 237
• can_v2_bricklet.FunctionSetStatusLEDConfig = 239
• can_v2_bricklet.FunctionReset = 243
• can_v2_bricklet.FunctionWriteUID = 248

func (*CANV2Bricklet) 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:

• can_v2_bricklet.FunctionSetFrameReadCallbackConfiguration = 3
• can_v2_bricklet.FunctionSetTransceiverConfiguration = 5
• can_v2_bricklet.FunctionSetQueueConfiguration = 7
• can_v2_bricklet.FunctionSetReadFilterConfiguration = 9
• can_v2_bricklet.FunctionSetCommunicationLEDConfig = 12
• can_v2_bricklet.FunctionSetErrorLEDConfig = 14
• can_v2_bricklet.FunctionSetFrameReadableCallbackConfiguration = 17
• can_v2_bricklet.FunctionSetErrorOccurredCallbackConfiguration = 20
• can_v2_bricklet.FunctionSetWriteFirmwarePointer = 237
• can_v2_bricklet.FunctionSetStatusLEDConfig = 239
• can_v2_bricklet.FunctionReset = 243
• can_v2_bricklet.FunctionWriteUID = 248

func (*CANV2Bricklet) 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.

Internal Functions¶

Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.

func (*CANV2Bricklet) SetBootloaderMode(mode uint8) (status uint8, err error)¶

Parameters:	mode – Type: uint8, Range: See constants
Returns:	status – Type: uint8, Range: See constants err – Type: error

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

For mode:

• can_v2_bricklet.BootloaderModeBootloader = 0
• can_v2_bricklet.BootloaderModeFirmware = 1
• can_v2_bricklet.BootloaderModeBootloaderWaitForReboot = 2
• can_v2_bricklet.BootloaderModeFirmwareWaitForReboot = 3
• can_v2_bricklet.BootloaderModeFirmwareWaitForEraseAndReboot = 4

For status:

• can_v2_bricklet.BootloaderStatusOK = 0
• can_v2_bricklet.BootloaderStatusInvalidMode = 1
• can_v2_bricklet.BootloaderStatusNoChange = 2
• can_v2_bricklet.BootloaderStatusEntryFunctionNotPresent = 3
• can_v2_bricklet.BootloaderStatusDeviceIdentifierIncorrect = 4
• can_v2_bricklet.BootloaderStatusCRCMismatch = 5

func (*CANV2Bricklet) GetBootloaderMode() (mode uint8, err error)¶

Returns:	mode – Type: uint8, Range: See constants err – Type: error

Returns the current bootloader mode, see SetBootloaderMode().

The following constants are available for this function:

For mode:

• can_v2_bricklet.BootloaderModeBootloader = 0
• can_v2_bricklet.BootloaderModeFirmware = 1
• can_v2_bricklet.BootloaderModeBootloaderWaitForReboot = 2
• can_v2_bricklet.BootloaderModeFirmwareWaitForReboot = 3
• can_v2_bricklet.BootloaderModeFirmwareWaitForEraseAndReboot = 4

func (*CANV2Bricklet) SetWriteFirmwarePointer(pointer uint32) (err error)¶

Parameters:	pointer – Type: uint32, Unit: 1 B, Range: [0 to 232 - 1]
Returns:	err – Type: error

Sets the firmware pointer for WriteFirmware(). The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

func (*CANV2Bricklet) WriteFirmware(data [64]uint8) (status uint8, err error)¶

Parameters:	data – Type: [64]uint8, Range: [0 to 255]
Returns:	status – Type: uint8, Range: [0 to 255] err – Type: error

Writes 64 Bytes of firmware at the position as written by SetWriteFirmwarePointer() before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

func (*CANV2Bricklet) WriteUID(uid uint32) (err error)¶

Parameters:	uid – Type: uint32, Range: [0 to 232 - 1]
Returns:	err – Type: error

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

func (*CANV2Bricklet) ReadUID() (uid uint32, err error)¶

Returns:	uid – Type: uint32, Range: [0 to 232 - 1] err – Type: error

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

Constants¶

can_v2_bricklet.DeviceIdentifier¶

This constant is used to identify a CAN Bricklet 2.0.

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

can_v2_bricklet.DeviceDisplayName¶

This constant represents the human readable name of a CAN Bricklet 2.0.