Go - RS232 Bricklet

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

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_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.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    rs232, _ := rs232_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 [60]rune, length uint8) {
        fmt.Println("Message (Length %d) %s", length, string(message[:length]))
    })

    // Enable read callback
    rs232.EnableReadCallback()

    var chars [60]rune
    testChars := []rune{'t', 'e', 's', 't'}
    copy(chars[:], testChars)

    rs232.Write(chars, 4)

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

API

The RS232 Bricklet API is defined in the package github.com/Tinkerforge/go-api-bindings/rs232_bricklet

Nearly every function of the Go bindings can return an BrickletError, implementing the error interface. The error can have one of the following values:

  • BrickletErrorSuccess = 0
  • BrickletErrorInvalidParameter = 1
  • BrickletErrorFunctionNotSupported = 2
  • BrickletErrorUnknownError = 3

which correspond to the values returned from Bricks and Bricklets.

All functions listed below are thread-safe.

Basic Functions

func NewRS232Bricklet(uid string, ipcon *IPConnection)(device RS232Bricklet, err error)

Creates a new RS232Bricklet 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 (*RS232Bricklet)Write(message [60]rune, length uint8)(written uint8, err error)

Writes a string of up to 60 characters to the RS232 interface. The string can be binary data, ASCII or similar is not necessary.

The length of the string has to be given as an additional parameter.

The return value is the number of bytes that could be written.

See (*RS232Bricklet) SetConfiguration for configuration possibilities regarding baudrate, parity and so on.

func (*RS232Bricklet)Read()(message [60]rune, length uint8, err error)

Returns the currently buffered message. The maximum length of message is 60. If the length is given as 0, there was no new data available.

Instead of polling with this function, you can also use callbacks. See (*RS232Bricklet) EnableReadCallback and (*RS232Bricklet) RegisterReadCallback callback.

func (*RS232Bricklet)SetConfiguration(baudrate Baudrate, parity Parity, stopbits Stopbits, wordlength Wordlength, hardwareFlowcontrol HardwareFlowcontrol, softwareFlowcontrol SoftwareFlowcontrol)(err error)

Sets the configuration for the RS232 communication. Available options:

  • Baudrate between 300 and 230400 baud.
  • Parity of none, odd, even or forced parity.
  • Stopbits can be 1 or 2.
  • Word length of 5 to 8.
  • Hard-/Software flow control can either be on or off but not both simultaneously on.

The default is: 115200 baud, parity none, 1 stop bit, word length 8, hard-/software flow control off.

The following constants are available for this function:

  • Baudrate300 = 0
  • Baudrate600 = 1
  • Baudrate1200 = 2
  • Baudrate2400 = 3
  • Baudrate4800 = 4
  • Baudrate9600 = 5
  • Baudrate14400 = 6
  • Baudrate19200 = 7
  • Baudrate28800 = 8
  • Baudrate38400 = 9
  • Baudrate57600 = 10
  • Baudrate115200 = 11
  • Baudrate230400 = 12
  • ParityNone = 0
  • ParityOdd = 1
  • ParityEven = 2
  • ParityForcedParity1 = 3
  • ParityForcedParity0 = 4
  • Stopbits1 = 1
  • Stopbits2 = 2
  • Wordlength5 = 5
  • Wordlength6 = 6
  • Wordlength7 = 7
  • Wordlength8 = 8
  • HardwareFlowcontrolOff = 0
  • HardwareFlowcontrolOn = 1
  • SoftwareFlowcontrolOff = 0
  • SoftwareFlowcontrolOn = 1
func (*RS232Bricklet)GetConfiguration()(baudrate Baudrate, parity Parity, stopbits Stopbits, wordlength Wordlength, hardwareFlowcontrol HardwareFlowcontrol, softwareFlowcontrol SoftwareFlowcontrol, err error)

Returns the configuration as set by (*RS232Bricklet) SetConfiguration.

The following constants are available for this function:

  • Baudrate300 = 0
  • Baudrate600 = 1
  • Baudrate1200 = 2
  • Baudrate2400 = 3
  • Baudrate4800 = 4
  • Baudrate9600 = 5
  • Baudrate14400 = 6
  • Baudrate19200 = 7
  • Baudrate28800 = 8
  • Baudrate38400 = 9
  • Baudrate57600 = 10
  • Baudrate115200 = 11
  • Baudrate230400 = 12
  • ParityNone = 0
  • ParityOdd = 1
  • ParityEven = 2
  • ParityForcedParity1 = 3
  • ParityForcedParity0 = 4
  • Stopbits1 = 1
  • Stopbits2 = 2
  • Wordlength5 = 5
  • Wordlength6 = 6
  • Wordlength7 = 7
  • Wordlength8 = 8
  • HardwareFlowcontrolOff = 0
  • HardwareFlowcontrolOn = 1
  • SoftwareFlowcontrolOff = 0
  • SoftwareFlowcontrolOn = 1
func (*RS232Bricklet)SetBreakCondition(breakTime uint16)(err error)

Sets a break condition (the TX output is forced to a logic 0 state). The parameter sets the hold-time of the break condition (in ms).

New in version 2.0.2 (Plugin).

Advanced Functions

func (*RS232Bricklet)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 (*RS232Bricklet)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 (*RS232Bricklet) 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 (*RS232Bricklet) SetResponseExpected for the list of function ID constants available for this function.

func (*RS232Bricklet)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:

  • FunctionEnableReadCallback = 3
  • FunctionDisableReadCallback = 4
  • FunctionSetConfiguration = 6
  • FunctionSetBreakCondition = 10
func (*RS232Bricklet)SetResponseExpectedAll(responseExpected bool)(err error)

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

func (*RS232Bricklet)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 (*RS232Bricklet)EnableReadCallback()(err error)

Enables the (*RS232Bricklet) RegisterReadCallback callback.

By default the callback is disabled.

func (*RS232Bricklet)DisableReadCallback()(err error)

Disables the (*RS232Bricklet) RegisterReadCallback callback.

By default the callback is disabled.

func (*RS232Bricklet)IsReadCallbackEnabled()(enabled bool, err error)

Returns true if the (*RS232Bricklet) 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.

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 (*RS232Bricklet)RegisterReadCallback(func(message [60]rune, length uint8))(registrationID uint64)

A callback can be registered for this event with the RegisterReadCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterReadCallback(registrationID uint64) function.

This callback is called if new data is available. The message has a maximum size of 60 characters. The actual length of the message is given in addition.

To enable this callback, use (*RS232Bricklet) EnableReadCallback.

func (*RS232Bricklet)RegisterErrorCallback(func(error Error))(registrationID uint64)

A callback can be registered for this event with the RegisterErrorCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterErrorCallback(registrationID uint64) function.

This callback is called if an error occurs. Possible errors are overrun, parity or framing error.

The following constants are available for this function:

  • ErrorOverrun = 1
  • ErrorParity = 2
  • ErrorFraming = 4

New in version 2.0.1 (Plugin).

Constants

rs232_bricklet.DeviceIdentifier

This constant is used to identify a RS232 Bricklet.

The (*RS232Bricklet) GetIdentity function and the (*IPConnection) RegisterEnumerateCallback callback of the IPConnection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

rs232_bricklet.DeviceDisplayName

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