Go - GPS Bricklet 2.0

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

Simple

Download (example_simple.go)

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package main

import (
    "fmt"
    "github.com/Tinkerforge/go-api-bindings/gps_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 GPS Bricklet 2.0.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    gps, _ := gps_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.

    // Get current coordinates.
    latitude, ns, longitude, ew, _ := gps.GetCoordinates()

    fmt.Printf("Latitude: %f °\n", float64(latitude)/1000000.0)
    fmt.Printf("N/S: \n", ns)
    fmt.Printf("Longitude: %f °\n", float64(longitude)/1000000.0)
    fmt.Printf("E/W: \n", ew)

    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/gps_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 GPS Bricklet 2.0.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    gps, _ := gps_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.

    gps.RegisterCoordinatesCallback(func(latitude uint32, ns rune, longitude uint32, ew rune) {
        fmt.Printf("Latitude: %f °\n", float64(latitude)/1000000.0)
        fmt.Printf("N/S: %c\n", ns)
        fmt.Printf("Longitude: %f °\n", float64(longitude)/1000000.0)
        fmt.Printf("E/W: %c\n", ew)
        fmt.Println()
    })

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

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

API

The GPS Bricklet 2.0's API is defined in the package github.com/Tinkerforge/go-api-bindings/gps_v2_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 NewGPSV2Bricklet(uid string, ipcon *IPConnection)(device GPSV2Bricklet, err error)

Creates a new GPSV2Bricklet object with the unique device ID uid and adds it to the IPConnection ipcon:

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

func (*GPSV2Bricklet)GetCoordinates()(latitude uint32, ns rune, longitude uint32, ew rune, err error)

Returns the GPS coordinates. Latitude and longitude are given in the DD.dddddd° format, the value 57123468 means 57.123468°. The parameter ns and ew are the cardinal directions for latitude and longitude. Possible values for ns and ew are 'N', 'S', 'E' and 'W' (north, south, east and west).

This data is only valid if there is currently a fix as indicated by (*GPSV2Bricklet) GetStatus.

func (*GPSV2Bricklet)GetStatus()(hasFix bool, satellitesView uint8, err error)

Returns if a fix is currently available as well as the, the number of satellites that are in view.

There is also a green LED on the Bricklet that indicates the fix status.

func (*GPSV2Bricklet)GetAltitude()(altitude int32, geoidalSeparation int32, err error)

Returns the current altitude and corresponding geoidal separation.

Both values are given in cm.

This data is only valid if there is currently a fix as indicated by (*GPSV2Bricklet) GetStatus.

func (*GPSV2Bricklet)GetMotion()(course uint32, speed uint32, err error)

Returns the current course and speed. Course is given in hundredths degree and speed is given in hundredths km/h. A course of 0° means the Bricklet is traveling north bound and 90° means it is traveling east bound.

Please note that this only returns useful values if an actual movement is present.

This data is only valid if there is currently a fix as indicated by (*GPSV2Bricklet) GetStatus.

func (*GPSV2Bricklet)GetDateTime()(date uint32, time uint32, err error)

Returns the current date and time. The date is given in the format ddmmyy and the time is given in the format hhmmss.sss. For example, 140713 means 14.05.13 as date and 195923568 means 19:59:23.568 as time.

func (*GPSV2Bricklet)GetSatelliteSystemStatus(satelliteSystem SatelliteSystem)(satelliteNumbers []uint8, fix Fix, pdop uint16, hdop uint16, vdop uint16, err error)

Returns the

  • satellite numbers list (up to 12 items)
  • fix value,
  • PDOP value,
  • HDOP value and
  • VDOP value

for a given satellite system. Currently GPS and GLONASS are supported, Galileo is not yet supported.

The GPS and GLONASS satellites have unique numbers and the satellite list gives the numbers of the satellites that are currently utilized. The number 0 is not a valid satellite number and can be ignored in the list.

The following constants are available for this function:

  • SatelliteSystemGPS = 0
  • SatelliteSystemGLONASS = 1
  • SatelliteSystemGalileo = 2
  • FixNoFix = 1
  • Fix2DFix = 2
  • Fix3DFix = 3
func (*GPSV2Bricklet)GetSatelliteStatus(satelliteSystem SatelliteSystem, satelliteNumber uint8)(elevation int16, azimuth int16, snr int16, err error)

Returns the current

  • elevation (0° - 90°),
  • azimuth (0° - 359°) and
  • SNR (0dB - 99dB)

for a given satellite and satellite system.

The satellite number here always goes from 1 to 32. For GLONASS it corresponds to the satellites 65-96.

Galileo is not yet supported.

The following constants are available for this function:

  • SatelliteSystemGPS = 0
  • SatelliteSystemGLONASS = 1
  • SatelliteSystemGalileo = 2

Advanced Functions

func (*GPSV2Bricklet)Restart(restartType RestartType)(err error)

Restarts the GPS Bricklet, the following restart types are available:

Value Description
0 Hot start (use all available data in the NV store)
1 Warm start (don't use ephemeris at restart)
2 Cold start (don't use time, position, almanacs and ephemeris at restart)
3 Factory reset (clear all system/user configurations at restart)

The following constants are available for this function:

  • RestartTypeHotStart = 0
  • RestartTypeWarmStart = 1
  • RestartTypeColdStart = 2
  • RestartTypeFactoryReset = 3
func (*GPSV2Bricklet)SetFixLEDConfig(config FixLEDConfig)(err error)

Sets the fix LED configuration. By default the LED shows if the Bricklet got a GPS fix yet. If a fix is established the LED turns on. If there is no fix then the LED is turned off.

You can also turn the LED permanently on/off, show a heartbeat or let it blink in sync with the PPS (pulse per second) output of the GPS module.

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

The following constants are available for this function:

  • FixLEDConfigOff = 0
  • FixLEDConfigOn = 1
  • FixLEDConfigShowHeartbeat = 2
  • FixLEDConfigShowFix = 3
  • FixLEDConfigShowPPS = 4
func (*GPSV2Bricklet)GetFixLEDConfig()(config FixLEDConfig, err error)

Returns the configuration as set by (*GPSV2Bricklet) SetFixLEDConfig

The following constants are available for this function:

  • FixLEDConfigOff = 0
  • FixLEDConfigOn = 1
  • FixLEDConfigShowHeartbeat = 2
  • FixLEDConfigShowFix = 3
  • FixLEDConfigShowPPS = 4
func (*GPSV2Bricklet)SetSBASConfig(sbasConfig SBAS)(err error)

If SBAS is enabled, the position accuracy increases (if SBAS satellites are in view), but the update rate is limited to 5Hz. With SBAS disabled the update rate is increased to 10Hz.

By default SBAS is enabled and the update rate is 5Hz.

The following constants are available for this function:

  • SBASEnabled = 0
  • SBASDisabled = 1

New in version 2.0.2 (Plugin).

func (*GPSV2Bricklet)GetSBASConfig()(sbasConfig SBAS, err error)

Returns the SBAS configuration as set by (*GPSV2Bricklet) SetSBASConfig

The following constants are available for this function:

  • SBASEnabled = 0
  • SBASDisabled = 1

New in version 2.0.2 (Plugin).

func (*GPSV2Bricklet)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 (*GPSV2Bricklet)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 (*GPSV2Bricklet) 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 (*GPSV2Bricklet) SetResponseExpected for the list of function ID constants available for this function.

func (*GPSV2Bricklet)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:

  • FunctionRestart = 6
  • FunctionSetFixLEDConfig = 9
  • FunctionSetCoordinatesCallbackPeriod = 11
  • FunctionSetStatusCallbackPeriod = 13
  • FunctionSetAltitudeCallbackPeriod = 15
  • FunctionSetMotionCallbackPeriod = 17
  • FunctionSetDateTimeCallbackPeriod = 19
  • FunctionSetSBASConfig = 27
  • FunctionSetWriteFirmwarePointer = 237
  • FunctionSetStatusLEDConfig = 239
  • FunctionReset = 243
  • FunctionWriteUID = 248
func (*GPSV2Bricklet)SetResponseExpectedAll(responseExpected bool)(err error)

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

func (*GPSV2Bricklet)GetSPITFPErrorCount()(errorCountAckChecksum uint32, errorCountMessageChecksum uint32, errorCountFrame uint32, errorCountOverflow uint32, err 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 (*GPSV2Bricklet)SetBootloaderMode(mode BootloaderMode)(status BootloaderStatus, err 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:

  • BootloaderModeBootloader = 0
  • BootloaderModeFirmware = 1
  • BootloaderModeBootloaderWaitForReboot = 2
  • BootloaderModeFirmwareWaitForReboot = 3
  • BootloaderModeFirmwareWaitForEraseAndReboot = 4
  • BootloaderStatusOK = 0
  • BootloaderStatusInvalidMode = 1
  • BootloaderStatusNoChange = 2
  • BootloaderStatusEntryFunctionNotPresent = 3
  • BootloaderStatusDeviceIdentifierIncorrect = 4
  • BootloaderStatusCRCMismatch = 5
func (*GPSV2Bricklet)GetBootloaderMode()(mode BootloaderMode, err error)

Returns the current bootloader mode, see (*GPSV2Bricklet) SetBootloaderMode.

The following constants are available for this function:

  • BootloaderModeBootloader = 0
  • BootloaderModeFirmware = 1
  • BootloaderModeBootloaderWaitForReboot = 2
  • BootloaderModeFirmwareWaitForReboot = 3
  • BootloaderModeFirmwareWaitForEraseAndReboot = 4
func (*GPSV2Bricklet)SetWriteFirmwarePointer(pointer uint32)(err error)

Sets the firmware pointer for (*GPSV2Bricklet) 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 (*GPSV2Bricklet)WriteFirmware(data [64]uint8)(status uint8, err error)

Writes 64 Bytes of firmware at the position as written by (*GPSV2Bricklet) 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 (*GPSV2Bricklet)SetStatusLEDConfig(config StatusLEDConfig)(err 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:

  • StatusLEDConfigOff = 0
  • StatusLEDConfigOn = 1
  • StatusLEDConfigShowHeartbeat = 2
  • StatusLEDConfigShowStatus = 3
func (*GPSV2Bricklet)GetStatusLEDConfig()(config StatusLEDConfig, err error)

Returns the configuration as set by (*GPSV2Bricklet) SetStatusLEDConfig

The following constants are available for this function:

  • StatusLEDConfigOff = 0
  • StatusLEDConfigOn = 1
  • StatusLEDConfigShowHeartbeat = 2
  • StatusLEDConfigShowStatus = 3
func (*GPSV2Bricklet)GetChipTemperature()(temperature int16, err error)

Returns the temperature in °C 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 (*GPSV2Bricklet)Reset()(err 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 (*GPSV2Bricklet)WriteUID(uid uint32)(err 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 (*GPSV2Bricklet)ReadUID()(uid uint32, err error)

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

func (*GPSV2Bricklet)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 (*GPSV2Bricklet)SetCoordinatesCallbackPeriod(period uint32)(err error)

Sets the period in ms with which the (*GPSV2Bricklet) RegisterCoordinatesCallback callback is triggered periodically. A value of 0 turns the callback off.

The (*GPSV2Bricklet) RegisterCoordinatesCallback callback is only triggered if the coordinates changed since the last triggering.

The default value is 0.

func (*GPSV2Bricklet)GetCoordinatesCallbackPeriod()(period uint32, err error)

Returns the period as set by (*GPSV2Bricklet) SetCoordinatesCallbackPeriod.

func (*GPSV2Bricklet)SetStatusCallbackPeriod(period uint32)(err error)

Sets the period in ms with which the (*GPSV2Bricklet) RegisterStatusCallback callback is triggered periodically. A value of 0 turns the callback off.

The (*GPSV2Bricklet) RegisterStatusCallback callback is only triggered if the status changed since the last triggering.

The default value is 0.

func (*GPSV2Bricklet)GetStatusCallbackPeriod()(period uint32, err error)

Returns the period as set by (*GPSV2Bricklet) SetStatusCallbackPeriod.

func (*GPSV2Bricklet)SetAltitudeCallbackPeriod(period uint32)(err error)

Sets the period in ms with which the (*GPSV2Bricklet) RegisterAltitudeCallback callback is triggered periodically. A value of 0 turns the callback off.

The (*GPSV2Bricklet) RegisterAltitudeCallback callback is only triggered if the altitude changed since the last triggering.

The default value is 0.

func (*GPSV2Bricklet)GetAltitudeCallbackPeriod()(period uint32, err error)

Returns the period as set by (*GPSV2Bricklet) SetAltitudeCallbackPeriod.

func (*GPSV2Bricklet)SetMotionCallbackPeriod(period uint32)(err error)

Sets the period in ms with which the (*GPSV2Bricklet) RegisterMotionCallback callback is triggered periodically. A value of 0 turns the callback off.

The (*GPSV2Bricklet) RegisterMotionCallback callback is only triggered if the motion changed since the last triggering.

The default value is 0.

func (*GPSV2Bricklet)GetMotionCallbackPeriod()(period uint32, err error)

Returns the period as set by (*GPSV2Bricklet) SetMotionCallbackPeriod.

func (*GPSV2Bricklet)SetDateTimeCallbackPeriod(period uint32)(err error)

Sets the period in ms with which the (*GPSV2Bricklet) RegisterDateTimeCallback callback is triggered periodically. A value of 0 turns the callback off.

The (*GPSV2Bricklet) RegisterDateTimeCallback callback is only triggered if the date or time changed since the last triggering.

The default value is 0.

func (*GPSV2Bricklet)GetDateTimeCallbackPeriod()(period uint32, err error)

Returns the period as set by (*GPSV2Bricklet) SetDateTimeCallbackPeriod.

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 (*GPSV2Bricklet)RegisterPulsePerSecondCallback(func())(callbackID uint64)

A callback can be registered for this event with the RegisterPulsePerSecondCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterPulsePerSecondCallback(callbackID uint64) function.

This callback is triggered precisely once per second, see PPS.

The precision of two subsequent pulses will be skewed because of the latency in the USB/RS485/Ethernet connection. But in the long run this will be very precise. For example a count of 3600 pulses will take exactly 1 hour.

func (*GPSV2Bricklet)RegisterCoordinatesCallback(func(latitude uint32, ns rune, longitude uint32, ew rune))(callbackID uint64)

A callback can be registered for this event with the RegisterCoordinatesCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterCoordinatesCallback(callbackID uint64) function.

This callback is triggered periodically with the period that is set by (*GPSV2Bricklet) SetCoordinatesCallbackPeriod. The parameters are the same as for (*GPSV2Bricklet) GetCoordinates.

The (*GPSV2Bricklet) RegisterCoordinatesCallback callback is only triggered if the coordinates changed since the last triggering and if there is currently a fix as indicated by (*GPSV2Bricklet) GetStatus.

func (*GPSV2Bricklet)RegisterStatusCallback(func(hasFix bool, satellitesView uint8))(callbackID uint64)

A callback can be registered for this event with the RegisterStatusCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterStatusCallback(callbackID uint64) function.

This callback is triggered periodically with the period that is set by (*GPSV2Bricklet) SetStatusCallbackPeriod. The parameters are the same as for (*GPSV2Bricklet) GetStatus.

The (*GPSV2Bricklet) RegisterStatusCallback callback is only triggered if the status changed since the last triggering.

func (*GPSV2Bricklet)RegisterAltitudeCallback(func(altitude int32, geoidalSeparation int32))(callbackID uint64)

A callback can be registered for this event with the RegisterAltitudeCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterAltitudeCallback(callbackID uint64) function.

This callback is triggered periodically with the period that is set by (*GPSV2Bricklet) SetAltitudeCallbackPeriod. The parameters are the same as for (*GPSV2Bricklet) GetAltitude.

The (*GPSV2Bricklet) RegisterAltitudeCallback callback is only triggered if the altitude changed since the last triggering and if there is currently a fix as indicated by (*GPSV2Bricklet) GetStatus.

func (*GPSV2Bricklet)RegisterMotionCallback(func(course uint32, speed uint32))(callbackID uint64)

A callback can be registered for this event with the RegisterMotionCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterMotionCallback(callbackID uint64) function.

This callback is triggered periodically with the period that is set by (*GPSV2Bricklet) SetMotionCallbackPeriod. The parameters are the same as for (*GPSV2Bricklet) GetMotion.

The (*GPSV2Bricklet) RegisterMotionCallback callback is only triggered if the motion changed since the last triggering and if there is currently a fix as indicated by (*GPSV2Bricklet) GetStatus.

func (*GPSV2Bricklet)RegisterDateTimeCallback(func(date uint32, time uint32))(callbackID uint64)

A callback can be registered for this event with the RegisterDateTimeCallback() function. This function returns the ID of the registered callback. An added callback can be removed with the DeregisterDateTimeCallback(callbackID uint64) function.

This callback is triggered periodically with the period that is set by (*GPSV2Bricklet) SetDateTimeCallbackPeriod. The parameters are the same as for (*GPSV2Bricklet) GetDateTime.

The (*GPSV2Bricklet) RegisterDateTimeCallback callback is only triggered if the date or time changed since the last triggering.

Constants

gps_v2_bricklet.DeviceIdentifier

This constant is used to identify a GPS Bricklet 2.0.

The (*GPSV2Bricklet) GetIdentity function and the (*IPConnection) RegisterEnumerateCallback callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

gps_v2_bricklet.DeviceDisplayName

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