Modbus - GPS Bricklet – Tinkerforge

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# Modbus - GPS Bricklet

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

## API

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

### Basic Functions

`BrickletGPS.``get_coordinates`

  Function ID: | 1
  Request: | empty payload

  Response:

  - latitude -- uint32
  - ns -- char
  - longitude -- uint32
  - ew -- char
  - pdop -- uint16
  - hdop -- uint16
  - vdop -- uint16
  - epe -- uint16

  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).

  PDOP, HDOP and VDOP are the dilution of precision (DOP) values. They specify the additional multiplicative effect of GPS satellite geometry on GPS precision. See here for more information. The values are give in hundredths.

  EPE is the "Estimated Position Error". The EPE is given in cm. This is not the absolute maximum error, it is the error with a specific confidence. See here for more information.

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

`BrickletGPS.``get_status`

  Function ID: | 2
  Request: | empty payload

  Response:

  - fix -- uint8
  - satellites_view -- uint8
  - satellites_used -- uint8

  Returns the current fix status, the number of satellites that are in view and the number of satellites that are currently used.

  Possible fix status values can be:

  Value | Description
  --- | ---
  1 | No Fix, `get_coordinates` and `get_altitude` return invalid data
  2 | 2D Fix, only `get_coordinates` returns valid data
  3 | 3D Fix, `get_coordinates` and `get_altitude` return valid data

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

`BrickletGPS.``get_altitude`

  Function ID: | 3
  Request: | empty payload

  Response:

  - altitude -- uint32
  - geoidal_separation -- uint32

  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 `get_status`.

`BrickletGPS.``get_motion`

  Function ID: | 4
  Request: | empty payload

  Response:

  - course -- uint32
  - speed -- uint32

  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 `get_status`.

`BrickletGPS.``get_date_time`

  Function ID: | 5
  Request: | empty payload

  Response:

  - date -- uint32
  - time -- uint32

  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.

### Advanced Functions

`BrickletGPS.``restart`

  Function ID: | 6

  Request:

  - restart_type -- uint8

  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)

`BrickletGPS.``get_identity`

  Function ID: | 255
  Request: | empty payload

  Response:

  - uid -- char[8]
  - connected_uid -- char[8]
  - position -- char
  - hardware_version -- uint8[3]
  - firmware_version -- uint8[3]
  - device_identifier -- uint16

  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.

### Callback Configuration Functions

`BrickletGPS.``set_coordinates_callback_period`

  Function ID: | 7

  Request:

  - period -- uint32

  Response: | no response

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

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

  The default value is 0.

`BrickletGPS.``get_coordinates_callback_period`

  Function ID: | 8
  Request: | empty payload

  Response:

  - period -- uint32

  Returns the period as set by `set_coordinates_callback_period`.

`BrickletGPS.``set_status_callback_period`

  Function ID: | 9

  Request:

  - period -- uint32

  Response: | no response

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

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

  The default value is 0.

`BrickletGPS.``get_status_callback_period`

  Function ID: | 10
  Request: | empty payload

  Response:

  - period -- uint32

  Returns the period as set by `set_status_callback_period`.

`BrickletGPS.``set_altitude_callback_period`

  Function ID: | 11

  Request:

  - period -- uint32

  Response: | no response

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

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

  The default value is 0.

`BrickletGPS.``get_altitude_callback_period`

  Function ID: | 12
  Request: | empty payload

  Response:

  - period -- uint32

  Returns the period as set by `set_altitude_callback_period`.

`BrickletGPS.``set_motion_callback_period`

  Function ID: | 13

  Request:

  - period -- uint32

  Response: | no response

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

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

  The default value is 0.

`BrickletGPS.``get_motion_callback_period`

  Function ID: | 14
  Request: | empty payload

  Response:

  - period -- uint32

  Returns the period as set by `set_motion_callback_period`.

`BrickletGPS.``set_date_time_callback_period`

  Function ID: | 15

  Request:

  - period -- uint32

  Response: | no response

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

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

  The default value is 0.

`BrickletGPS.``get_date_time_callback_period`

  Function ID: | 16
  Request: | empty payload

  Response:

  - period -- uint32

  Returns the period as set by `set_date_time_callback_period`.

### Callbacks

`BrickletGPS.``CALLBACK_COORDINATES`

  Function ID: | 17

  Response:

  - latitude -- uint32
  - ns -- char
  - longitude -- uint32
  - ew -- char
  - pdop -- uint16
  - hdop -- uint16
  - vdop -- uint16
  - epe -- uint16

  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`.

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

`BrickletGPS.``CALLBACK_STATUS`

  Function ID: | 18

  Response:

  - fix -- uint8
  - satellites_view -- uint8
  - satellites_used -- uint8

  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`.

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

`BrickletGPS.``CALLBACK_ALTITUDE`

  Function ID: | 19

  Response:

  - altitude -- uint32
  - geoidal_separation -- uint32

  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`.

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

`BrickletGPS.``CALLBACK_MOTION`

  Function ID: | 20

  Response:

  - course -- uint32
  - speed -- uint32

  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`.

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

`BrickletGPS.``CALLBACK_DATE_TIME`

  Function ID: | 21

  Response:

  - date -- uint32
  - time -- uint32

  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`.

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

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