Modbus - GPS Bricklet 2.0

This is the description of the Modbus protocol for the GPS Bricklet 2.0. General information and technical specifications for the GPS Bricklet 2.0 are summarized in its hardware description.

API

A general description of the Modbus protocol structure can be found here.

Basic Functions

BrickletGPSV2.get_coordinates
Function ID:
  • 1
Request:
  • empty payload
Response:
  • latitude – Type: uint32, Unit: 1/1000000 °, Range: [0 to 90000000]
  • ns – Type: char, Range: ['N', 'S']
  • longitude – Type: uint32, Unit: 1/1000000 °, Range: [0 to 180000000]
  • ew – Type: char, Range: ['E', 'W']

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 get_status.

BrickletGPSV2.get_status
Function ID:
  • 2
Request:
  • empty payload
Response:
  • has_fix – Type: bool
  • satellites_view – Type: uint8, Range: [0 to 255]

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.

BrickletGPSV2.get_altitude
Function ID:
  • 3
Request:
  • empty payload
Response:
  • altitude – Type: int32, Unit: 1 cm, Range: [-231 to 231 - 1]
  • geoidal_separation – Type: int32, Unit: 1 cm, Range: [-231 to 231 - 1]

Returns the current altitude and corresponding geoidal separation.

This data is only valid if there is currently a fix as indicated by get_status.

BrickletGPSV2.get_motion
Function ID:
  • 4
Request:
  • empty payload
Response:
  • course – Type: uint32, Unit: 1/100 °, Range: [0 to 36000]
  • speed – Type: uint32, Unit: 1/100 km/h, Range: [0 to 232 - 1]

Returns the current course and speed. 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 get_status.

BrickletGPSV2.get_date_time
Function ID:
  • 5
Request:
  • empty payload
Response:
  • date – Type: uint32, Range: [10100 to 311299]
  • time – Type: uint32, Range: [0 to 235959999]

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 14.07.13 as date and 195923568 means 19:59:23.568 as time.

BrickletGPSV2.get_satellite_system_status_low_level
Function ID:
  • 7
Request:
  • satellite_system – Type: uint8, Range: See meanings
Response:
  • satellite_numbers_length – Type: uint8, Range: [0 to 12]
  • satellite_numbers_data – Type: uint8[12], Range: [0 to 255]
  • fix – Type: uint8, Range: See meanings
  • pdop – Type: uint16, Unit: 1/100, Range: [0 to 216 - 1]
  • hdop – Type: uint16, Unit: 1/100, Range: [0 to 216 - 1]
  • vdop – Type: uint16, Unit: 1/100, Range: [0 to 216 - 1]

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 meanings are defined for the elements of this function:

For satellite_system:

  • 0 = GPS
  • 1 = GLONASS
  • 2 = Galileo

For fix:

  • 1 = No Fix
  • 2 = 2D Fix
  • 3 = 3D Fix
BrickletGPSV2.get_satellite_status
Function ID:
  • 8
Request:
  • satellite_system – Type: uint8, Range: See meanings
  • satellite_number – Type: uint8, Range: [1 to 32]
Response:
  • elevation – Type: int16, Unit: 1 °, Range: [0 to 90]
  • azimuth – Type: int16, Unit: 1 °, Range: [0 to 359]
  • snr – Type: int16, Unit: 1 dB, Range: [0 to 99]

Returns the current elevation, azimuth and SNR 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 meanings are defined for the elements of this function:

For satellite_system:

  • 0 = GPS
  • 1 = GLONASS
  • 2 = Galileo

Advanced Functions

BrickletGPSV2.restart
Function ID:
  • 6
Request:
  • restart_type – Type: uint8, Range: See meanings
Response:
  • no response

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 meanings are defined for the elements of this function:

For restart_type:

  • 0 = Hot Start
  • 1 = Warm Start
  • 2 = Cold Start
  • 3 = Factory Reset
BrickletGPSV2.set_fix_led_config
Function ID:
  • 9
Request:
  • config – Type: uint8, Range: See meanings, Default: 3
Response:
  • no response

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 meanings are defined for the elements of this function:

For config:

  • 0 = Off
  • 1 = On
  • 2 = Show Heartbeat
  • 3 = Show Fix
  • 4 = Show PPS
BrickletGPSV2.get_fix_led_config
Function ID:
  • 10
Request:
  • empty payload
Response:
  • config – Type: uint8, Range: See meanings, Default: 3

Returns the configuration as set by set_fix_led_config

The following meanings are defined for the elements of this function:

For config:

  • 0 = Off
  • 1 = On
  • 2 = Show Heartbeat
  • 3 = Show Fix
  • 4 = Show PPS
BrickletGPSV2.set_sbas_config
Function ID:
  • 27
Request:
  • sbas_config – Type: uint8, Range: See meanings, Default: 0
Response:
  • no response

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.

New in version 2.0.2 (Plugin).

The following meanings are defined for the elements of this function:

For sbas_config:

  • 0 = Enabled
  • 1 = Disabled
BrickletGPSV2.get_sbas_config
Function ID:
  • 28
Request:
  • empty payload
Response:
  • sbas_config – Type: uint8, Range: See meanings, Default: 0

Returns the SBAS configuration as set by set_sbas_config

New in version 2.0.2 (Plugin).

The following meanings are defined for the elements of this function:

For sbas_config:

  • 0 = Enabled
  • 1 = Disabled
BrickletGPSV2.get_spitfp_error_count
Function ID:
  • 234
Request:
  • empty payload
Response:
  • error_count_ack_checksum – Type: uint32, Range: [0 to 232 - 1]
  • error_count_message_checksum – Type: uint32, Range: [0 to 232 - 1]
  • error_count_frame – Type: uint32, Range: [0 to 232 - 1]
  • error_count_overflow – Type: uint32, Range: [0 to 232 - 1]

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.

BrickletGPSV2.set_status_led_config
Function ID:
  • 239
Request:
  • config – Type: uint8, Range: See meanings, Default: 3
Response:
  • no response

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 meanings are defined for the elements of this function:

For config:

  • 0 = Off
  • 1 = On
  • 2 = Show Heartbeat
  • 3 = Show Status
BrickletGPSV2.get_status_led_config
Function ID:
  • 240
Request:
  • empty payload
Response:
  • config – Type: uint8, Range: See meanings, Default: 3

Returns the configuration as set by set_status_led_config

The following meanings are defined for the elements of this function:

For config:

  • 0 = Off
  • 1 = On
  • 2 = Show Heartbeat
  • 3 = Show Status
BrickletGPSV2.get_chip_temperature
Function ID:
  • 242
Request:
  • empty payload
Response:
  • temperature – Type: int16, Unit: 1 °C, Range: [-215 to 215 - 1]

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.

BrickletGPSV2.reset
Function ID:
  • 243
Request:
  • empty payload
Response:
  • no response

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!

BrickletGPSV2.get_identity
Function ID:
  • 255
Request:
  • empty payload
Response:
  • uid – Type: char[8]
  • connected_uid – Type: char[8]
  • position – Type: char, Range: ['a' to 'h', 'z']
  • hardware_version – Type: uint8[3]
    • 0: major – Type: uint8, Range: [0 to 255]
    • 1: minor – Type: uint8, Range: [0 to 255]
    • 2: revision – Type: uint8, Range: [0 to 255]
  • firmware_version – Type: uint8[3]
    • 0: major – Type: uint8, Range: [0 to 255]
    • 1: minor – Type: uint8, Range: [0 to 255]
    • 2: revision – Type: uint8, Range: [0 to 255]
  • device_identifier – Type: uint16, Range: [0 to 216 - 1]

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

Callback Configuration Functions

BrickletGPSV2.set_coordinates_callback_period
Function ID:
  • 11
Request:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Response:
  • no response

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

The CALLBACK_COORDINATES callback is only triggered if the coordinates changed since the last triggering.

BrickletGPSV2.get_coordinates_callback_period
Function ID:
  • 12
Request:
  • empty payload
Response:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_coordinates_callback_period.

BrickletGPSV2.set_status_callback_period
Function ID:
  • 13
Request:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Response:
  • no response

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

The CALLBACK_STATUS callback is only triggered if the status changed since the last triggering.

BrickletGPSV2.get_status_callback_period
Function ID:
  • 14
Request:
  • empty payload
Response:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_status_callback_period.

BrickletGPSV2.set_altitude_callback_period
Function ID:
  • 15
Request:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Response:
  • no response

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

The CALLBACK_ALTITUDE callback is only triggered if the altitude changed since the last triggering.

BrickletGPSV2.get_altitude_callback_period
Function ID:
  • 16
Request:
  • empty payload
Response:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_altitude_callback_period.

BrickletGPSV2.set_motion_callback_period
Function ID:
  • 17
Request:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Response:
  • no response

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

The CALLBACK_MOTION callback is only triggered if the motion changed since the last triggering.

BrickletGPSV2.get_motion_callback_period
Function ID:
  • 18
Request:
  • empty payload
Response:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_motion_callback_period.

BrickletGPSV2.set_date_time_callback_period
Function ID:
  • 19
Request:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
Response:
  • no response

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

The CALLBACK_DATE_TIME callback is only triggered if the date or time changed since the last triggering.

BrickletGPSV2.get_date_time_callback_period
Function ID:
  • 20
Request:
  • empty payload
Response:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by set_date_time_callback_period.

Callbacks

BrickletGPSV2.CALLBACK_PULSE_PER_SECOND
Function ID:
  • 21
Response:
  • empty payload

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.

BrickletGPSV2.CALLBACK_COORDINATES
Function ID:
  • 22
Response:
  • latitude – Type: uint32, Unit: 1/1000000 °, Range: [0 to 90000000]
  • ns – Type: char, Range: ['N', 'S']
  • longitude – Type: uint32, Unit: 1/1000000 °, Range: [0 to 180000000]
  • ew – Type: char, Range: ['E', 'W']

This callback is triggered periodically with the period that is set by set_coordinates_callback_period. The parameters are the same as for get_coordinates.

The CALLBACK_COORDINATES callback is only triggered if the coordinates changed since the last triggering and if there is currently a fix as indicated by get_status.

BrickletGPSV2.CALLBACK_STATUS
Function ID:
  • 23
Response:
  • has_fix – Type: bool
  • satellites_view – Type: uint8, Range: [0 to 255]

This callback is triggered periodically with the period that is set by set_status_callback_period. The parameters are the same as for get_status.

The CALLBACK_STATUS callback is only triggered if the status changed since the last triggering.

BrickletGPSV2.CALLBACK_ALTITUDE
Function ID:
  • 24
Response:
  • altitude – Type: int32, Unit: 1 cm, Range: [-231 to 231 - 1]
  • geoidal_separation – Type: int32, Unit: 1 cm, Range: [-231 to 231 - 1]

This callback is triggered periodically with the period that is set by set_altitude_callback_period. The parameters are the same as for get_altitude.

The CALLBACK_ALTITUDE callback is only triggered if the altitude changed since the last triggering and if there is currently a fix as indicated by get_status.

BrickletGPSV2.CALLBACK_MOTION
Function ID:
  • 25
Response:
  • course – Type: uint32, Unit: 1/100 °, Range: [0 to 36000]
  • speed – Type: uint32, Unit: 1/100 km/h, Range: [0 to 232 - 1]

This callback is triggered periodically with the period that is set by set_motion_callback_period. The parameters are the same as for get_motion.

The CALLBACK_MOTION callback is only triggered if the motion changed since the last triggering and if there is currently a fix as indicated by get_status.

BrickletGPSV2.CALLBACK_DATE_TIME
Function ID:
  • 26
Response:
  • date – Type: uint32, Range: [10100 to 311299]
  • time – Type: uint32, Range: [0 to 235959999]

This callback is triggered periodically with the period that is set by set_date_time_callback_period. The parameters are the same as for get_date_time.

The CALLBACK_DATE_TIME callback is only triggered if the date or time changed since the last triggering.

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.

BrickletGPSV2.set_bootloader_mode
Function ID:
  • 235
Request:
  • mode – Type: uint8, Range: See meanings
Response:
  • status – Type: uint8, Range: See meanings

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 meanings are defined for the elements of this function:

For mode:

  • 0 = Bootloader
  • 1 = Firmware
  • 2 = Bootloader Wait For Reboot
  • 3 = Firmware Wait For Reboot
  • 4 = Firmware Wait For Erase And Reboot

For status:

  • 0 = OK
  • 1 = Invalid Mode
  • 2 = No Change
  • 3 = Entry Function Not Present
  • 4 = Device Identifier Incorrect
  • 5 = CRC Mismatch
BrickletGPSV2.get_bootloader_mode
Function ID:
  • 236
Request:
  • empty payload
Response:
  • mode – Type: uint8, Range: See meanings

Returns the current bootloader mode, see set_bootloader_mode.

The following meanings are defined for the elements of this function:

For mode:

  • 0 = Bootloader
  • 1 = Firmware
  • 2 = Bootloader Wait For Reboot
  • 3 = Firmware Wait For Reboot
  • 4 = Firmware Wait For Erase And Reboot
BrickletGPSV2.set_write_firmware_pointer
Function ID:
  • 237
Request:
  • pointer – Type: uint32, Unit: 1 B, Range: [0 to 232 - 1]
Response:
  • no response

Sets the firmware pointer for write_firmware. 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.

BrickletGPSV2.write_firmware
Function ID:
  • 238
Request:
  • data – Type: uint8[64], Range: [0 to 255]
Response:
  • status – Type: uint8, Range: [0 to 255]

Writes 64 Bytes of firmware at the position as written by set_write_firmware_pointer 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.

BrickletGPSV2.write_uid
Function ID:
  • 248
Request:
  • uid – Type: uint32, Range: [0 to 232 - 1]
Response:
  • no response

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.

BrickletGPSV2.read_uid
Function ID:
  • 249
Request:
  • empty payload
Response:
  • uid – Type: uint32, Range: [0 to 232 - 1]

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