Go - RS232 Bricklet 2.0

This is the description of the Go API bindings for the RS232 Bricklet 2.0. General information and technical specifications for the RS232 Bricklet 2.0 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).

Loopback

Download (example_loopback.go)

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package main

import (
    "fmt"
    "github.com/Tinkerforge/go-api-bindings/ipconnection"
    "github.com/Tinkerforge/go-api-bindings/rs232_v2_bricklet"
)

// For this example connect the RX1 and TX pin to receive the send message

const ADDR string = "localhost:4223"
const UID string = "XYZ" // Change XYZ to the UID of your RS232 Bricklet 2.0.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    rs232, _ := rs232_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.

    rs232.RegisterReadCallback(func(message []rune) {
        fmt.Println(string(message))
    })

    // Enable read callback
    rs232.EnableReadCallback()

    // Write "test" string
    rs232.Write([]rune{'t', 'e', 's', 't'})

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

API

The RS232 Bricklet 2.0 API is defined in the package github.com/Tinkerforge/go-api-bindings/rs232_v2_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 rs232_v2_bricklet.New(uid string, ipcon *IPConnection) (device RS232V2Bricklet, err error)
Parameters:
  • uid – Type: string
  • ipcon – Type: *IPConnection
Returns:
  • device – Type: RS232V2Bricklet
  • err – Type: error

Creates a new RS232V2Bricklet object with the unique device ID uid and adds it to the IPConnection ipcon:

device, err := rs232_v2_bricklet.New("YOUR_DEVICE_UID", &ipcon)

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

func (*RS232V2Bricklet) Write(message []rune) (messageChunkWritten uint64, err error)
Parameters:
  • message – Type: []rune, Length: variable
Returns:
  • messageWritten – Type: uint16, Range: [0 to 216 - 1]
  • err – Type: error

Writes characters to the RS232 interface. The characters can be binary data, ASCII or similar is not necessary.

The return value is the number of characters that were written.

See SetConfiguration() for configuration possibilities regarding baud rate, parity and so on.

func (*RS232V2Bricklet) Read(length uint16) (message []rune, err error)
Parameters:
  • length – Type: uint16, Range: [0 to 216 - 1]
Returns:
  • message – Type: []rune, Length: variable
  • err – Type: error

Returns up to length characters from receive buffer.

Instead of polling with this function, you can also use callbacks. But note that this function will return available data only when the read callback is disabled. See EnableReadCallback() and RegisterReadCallback callback.

func (*RS232V2Bricklet) SetConfiguration(baudrate uint32, parity uint8, stopbits uint8, wordlength uint8, flowcontrol uint8) (err error)
Parameters:
  • baudrate – Type: uint32, Unit: 1 Bd, Range: [100 to 2000000], Default: 115200
  • parity – Type: uint8, Range: See constants, Default: 0
  • stopbits – Type: uint8, Range: See constants, Default: 1
  • wordlength – Type: uint8, Range: See constants, Default: 8
  • flowcontrol – Type: uint8, Range: See constants, Default: 0
Returns:
  • err – Type: error

Sets the configuration for the RS232 communication.

The following constants are available for this function:

For parity:

  • rs232_v2_bricklet.ParityNone = 0
  • rs232_v2_bricklet.ParityOdd = 1
  • rs232_v2_bricklet.ParityEven = 2

For stopbits:

  • rs232_v2_bricklet.Stopbits1 = 1
  • rs232_v2_bricklet.Stopbits2 = 2

For wordlength:

  • rs232_v2_bricklet.Wordlength5 = 5
  • rs232_v2_bricklet.Wordlength6 = 6
  • rs232_v2_bricklet.Wordlength7 = 7
  • rs232_v2_bricklet.Wordlength8 = 8

For flowcontrol:

  • rs232_v2_bricklet.FlowcontrolOff = 0
  • rs232_v2_bricklet.FlowcontrolSoftware = 1
  • rs232_v2_bricklet.FlowcontrolHardware = 2
func (*RS232V2Bricklet) GetConfiguration() (baudrate uint32, parity uint8, stopbits uint8, wordlength uint8, flowcontrol uint8, err error)
Returns:
  • baudrate – Type: uint32, Unit: 1 Bd, Range: [100 to 2000000], Default: 115200
  • parity – Type: uint8, Range: See constants, Default: 0
  • stopbits – Type: uint8, Range: See constants, Default: 1
  • wordlength – Type: uint8, Range: See constants, Default: 8
  • flowcontrol – Type: uint8, Range: See constants, Default: 0
  • err – Type: error

Returns the configuration as set by SetConfiguration().

The following constants are available for this function:

For parity:

  • rs232_v2_bricklet.ParityNone = 0
  • rs232_v2_bricklet.ParityOdd = 1
  • rs232_v2_bricklet.ParityEven = 2

For stopbits:

  • rs232_v2_bricklet.Stopbits1 = 1
  • rs232_v2_bricklet.Stopbits2 = 2

For wordlength:

  • rs232_v2_bricklet.Wordlength5 = 5
  • rs232_v2_bricklet.Wordlength6 = 6
  • rs232_v2_bricklet.Wordlength7 = 7
  • rs232_v2_bricklet.Wordlength8 = 8

For flowcontrol:

  • rs232_v2_bricklet.FlowcontrolOff = 0
  • rs232_v2_bricklet.FlowcontrolSoftware = 1
  • rs232_v2_bricklet.FlowcontrolHardware = 2

Advanced Functions

func (*RS232V2Bricklet) SetBufferConfig(sendBufferSize uint16, receiveBufferSize uint16) (err error)
Parameters:
  • sendBufferSize – Type: uint16, Unit: 1 B, Range: [1024 to 9216], Default: 5120
  • receiveBufferSize – Type: uint16, Unit: 1 B, Range: [1024 to 9216], Default: 5120
Returns:
  • err – Type: error

Sets the send and receive buffer size in byte. In total the buffers have to be 10240 byte (10KiB) in size, the minimum buffer size is 1024 byte (1KiB) for each.

The current buffer content is lost if this function is called.

The send buffer holds data that is given by Write() and can not be written yet. The receive buffer holds data that is received through RS232 but could not yet be send to the user, either by Read() or through RegisterReadCallback callback.

func (*RS232V2Bricklet) GetBufferConfig() (sendBufferSize uint16, receiveBufferSize uint16, err error)
Returns:
  • sendBufferSize – Type: uint16, Unit: 1 B, Range: [1024 to 9216], Default: 5120
  • receiveBufferSize – Type: uint16, Unit: 1 B, Range: [1024 to 9216], Default: 5120
  • err – Type: error

Returns the buffer configuration as set by SetBufferConfig().

func (*RS232V2Bricklet) GetBufferStatus() (sendBufferUsed uint16, receiveBufferUsed uint16, err error)
Returns:
  • sendBufferUsed – Type: uint16, Unit: 1 B, Range: [1024 to 9216]
  • receiveBufferUsed – Type: uint16, Unit: 1 B, Range: [1024 to 9216]
  • err – Type: error

Returns the currently used bytes for the send and received buffer.

See SetBufferConfig() for buffer size configuration.

func (*RS232V2Bricklet) GetErrorCount() (errorCountOverrun uint32, errorCountParity uint32, err error)
Returns:
  • errorCountOverrun – Type: uint32, Range: [0 to 232 - 1]
  • errorCountParity – Type: uint32, Range: [0 to 232 - 1]
  • err – Type: error

Returns the current number of overrun and parity errors.

func (*RS232V2Bricklet) 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 (*RS232V2Bricklet) 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:

  • rs232_v2_bricklet.BootloaderModeBootloader = 0
  • rs232_v2_bricklet.BootloaderModeFirmware = 1
  • rs232_v2_bricklet.BootloaderModeBootloaderWaitForReboot = 2
  • rs232_v2_bricklet.BootloaderModeFirmwareWaitForReboot = 3
  • rs232_v2_bricklet.BootloaderModeFirmwareWaitForEraseAndReboot = 4

For status:

  • rs232_v2_bricklet.BootloaderStatusOK = 0
  • rs232_v2_bricklet.BootloaderStatusInvalidMode = 1
  • rs232_v2_bricklet.BootloaderStatusNoChange = 2
  • rs232_v2_bricklet.BootloaderStatusEntryFunctionNotPresent = 3
  • rs232_v2_bricklet.BootloaderStatusDeviceIdentifierIncorrect = 4
  • rs232_v2_bricklet.BootloaderStatusCRCMismatch = 5
func (*RS232V2Bricklet) 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:

  • rs232_v2_bricklet.BootloaderModeBootloader = 0
  • rs232_v2_bricklet.BootloaderModeFirmware = 1
  • rs232_v2_bricklet.BootloaderModeBootloaderWaitForReboot = 2
  • rs232_v2_bricklet.BootloaderModeFirmwareWaitForReboot = 3
  • rs232_v2_bricklet.BootloaderModeFirmwareWaitForEraseAndReboot = 4
func (*RS232V2Bricklet) 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 (*RS232V2Bricklet) 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 (*RS232V2Bricklet) 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:

  • rs232_v2_bricklet.StatusLEDConfigOff = 0
  • rs232_v2_bricklet.StatusLEDConfigOn = 1
  • rs232_v2_bricklet.StatusLEDConfigShowHeartbeat = 2
  • rs232_v2_bricklet.StatusLEDConfigShowStatus = 3
func (*RS232V2Bricklet) 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:

  • rs232_v2_bricklet.StatusLEDConfigOff = 0
  • rs232_v2_bricklet.StatusLEDConfigOn = 1
  • rs232_v2_bricklet.StatusLEDConfigShowHeartbeat = 2
  • rs232_v2_bricklet.StatusLEDConfigShowStatus = 3
func (*RS232V2Bricklet) 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 (*RS232V2Bricklet) 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 (*RS232V2Bricklet) 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 (*RS232V2Bricklet) 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.

func (*RS232V2Bricklet) 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 (*RS232V2Bricklet) EnableReadCallback() (err error)
Returns:
  • err – Type: error

Enables the RegisterReadCallback callback.

By default the callback is disabled.

func (*RS232V2Bricklet) DisableReadCallback() (err error)
Returns:
  • err – Type: error

Disables the RegisterReadCallback callback.

By default the callback is disabled.

func (*RS232V2Bricklet) IsReadCallbackEnabled() (enabled bool, err error)
Returns:
  • enabled – Type: bool, Default: false
  • err – Type: error

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

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 (*RS232V2Bricklet) RegisterReadCallback(func(message []rune)) (registrationId uint64)
Callback Parameters:
  • message – Type: []rune, Length: variable
Returns:
  • registrationId – Type: uint64

This callback is called if new data is available.

To enable this callback, use EnableReadCallback().

Note

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

func (*RS232V2Bricklet) RegisterErrorCountCallback(func(errorCountOverrun uint32, errorCountParity uint32)) (registrationId uint64)
Callback Parameters:
  • errorCountOverrun – Type: uint32, Range: [0 to 232 - 1]
  • errorCountParity – Type: uint32, Range: [0 to 232 - 1]
Returns:
  • registrationId – Type: uint64

This callback is called if a new error occurs. It returns the current overrun and parity error count.

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 (*RS232V2Bricklet) 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 (*RS232V2Bricklet) 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 send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • rs232_v2_bricklet.FunctionEnableReadCallback = 3
  • rs232_v2_bricklet.FunctionDisableReadCallback = 4
  • rs232_v2_bricklet.FunctionSetConfiguration = 6
  • rs232_v2_bricklet.FunctionSetBufferConfig = 8
  • rs232_v2_bricklet.FunctionSetWriteFirmwarePointer = 237
  • rs232_v2_bricklet.FunctionSetStatusLEDConfig = 239
  • rs232_v2_bricklet.FunctionReset = 243
  • rs232_v2_bricklet.FunctionWriteUID = 248
func (*RS232V2Bricklet) 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 send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • rs232_v2_bricklet.FunctionEnableReadCallback = 3
  • rs232_v2_bricklet.FunctionDisableReadCallback = 4
  • rs232_v2_bricklet.FunctionSetConfiguration = 6
  • rs232_v2_bricklet.FunctionSetBufferConfig = 8
  • rs232_v2_bricklet.FunctionSetWriteFirmwarePointer = 237
  • rs232_v2_bricklet.FunctionSetStatusLEDConfig = 239
  • rs232_v2_bricklet.FunctionReset = 243
  • rs232_v2_bricklet.FunctionWriteUID = 248
func (*RS232V2Bricklet) 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

rs232_v2_bricklet.DeviceIdentifier

This constant is used to identify a RS232 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.

rs232_v2_bricklet.DeviceDisplayName

This constant represents the human readable name of a RS232 Bricklet 2.0.