This is the description of the Python API bindings for the GPS Bricklet. General information and technical specifications for the GPS Bricklet are summarized in its hardware description.
An installation guide for the Python API bindings is part of their general description.
The example code below is Public Domain (CC0 1.0).
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
HOST = "localhost"
PORT = 4223
UID = "ABC" # Change to your UID
from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_gps import GPS
if __name__ == "__main__":
ipcon = IPConnection() # Create IP connection
gps = GPS(UID, ipcon) # Create device object
ipcon.connect(HOST, PORT) # Connect to brickd
# Don't use device before ipcon is connected
# Get current coordinates
coords = gps.get_coordinates()
print('Latitude: ' + str(coords.latitude/1000000.0) + '° ' + coords.ns)
print('Longitude: ' + str(coords.longitude/1000000.0) + '° ' + coords.ew)
raw_input('Press key to exit\n') # Use input() in Python 3
ipcon.disconnect()
|
Download (example_callback.py)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
HOST = "localhost"
PORT = 4223
UID = "ABC" # Change to your UID
from tinkerforge.ip_connection import IPConnection
from tinkerforge.bricklet_gps import GPS
# Callback function for coordinates
def cb_coordinates(latitude, ns, longitude, ew, pdop, hdop, vdop, epe):
print('Latitude: ' + str(latitude/1000000.0) + '° ' + ns)
print('Longitude: ' + str(longitude/1000000.0) + '° ' + ew)
if __name__ == "__main__":
ipcon = IPConnection() # Create IP connection
gps = GPS(UID, ipcon) # Create device object
ipcon.connect(HOST, PORT) # Connect to brickd
# Don't use device before ipcon is connected
# Set Period for coordinates callback to 1s (1000ms)
# Note: The callback is only called every second if the
# coordinates have changed since the last call!
gps.set_coordinates_callback_period(1000)
# Register coordinates callback to function cb_coordinates
gps.register_callback(gps.CALLBACK_COORDINATES, cb_coordinates)
raw_input('Press key to exit\n') # Use input() in Python 3
ipcon.disconnect()
|
Generally, every method of the Python bindings can throw an tinkerforge.ip_connection.Error exception that has a value and a description property. value can have different values:
All methods listed below are thread-safe.
Parameters: |
|
---|
Creates an object with the unique device ID uid:
gps = GPS("YOUR_DEVICE_UID", ipcon)
This object can then be used after the IP Connection is connected (see examples above).
Return type: | (int, chr, int, chr, int, int, int, int) |
---|
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().
The returned namedtuple has the variables latitude, ns, longitude, ew, pdop, hdop, vdop and epe.
Return type: | (int, int, int) |
---|
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.
The following constants are available for this function:
The returned namedtuple has the variables fix, satellites_view and satellites_used.
Return type: | (int, int) |
---|
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().
The returned namedtuple has the variables altitude and geoidal_separation.
Return type: | (int, int) |
---|
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().
The returned namedtuple has the variables course and speed.
Return type: | (int, int) |
---|
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.
The returned namedtuple has the variables date and time.
Parameters: | restart_type -- int |
---|---|
Return type: | None |
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:
Return type: | [int, int, int] |
---|
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.
Parameters: | function_id -- int |
---|---|
Return type: | bool |
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 set_response_expected(). 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 set_response_expected() for the list of function ID constants available for this function.
Parameters: |
|
---|---|
Return type: | None |
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 and callbacks it is always disabled.
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:
Parameters: | response_expected -- bool |
---|---|
Return type: | None |
Changes the response expected flag for all setter and callback configuration functions of this device at once.
Return type: | (str, str, chr, [int, int, int], [int, int, int], int) |
---|
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.
The returned namedtuple has the variables uid, connected_uid, position, hardware_version, firmware_version and device_identifier.
Parameters: |
|
---|---|
Return type: | None |
Registers a callback with ID id to the function callback. The available IDs with corresponding function signatures are listed below.
Parameters: | period -- int |
---|---|
Return type: | None |
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.
Return type: | int |
---|
Returns the period as set by set_coordinates_callback_period().
Parameters: | period -- int |
---|---|
Return type: | None |
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.
Return type: | int |
---|
Returns the period as set by set_status_callback_period().
Parameters: | period -- int |
---|---|
Return type: | None |
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.
Return type: | int |
---|
Returns the period as set by set_altitude_callback_period().
Parameters: | period -- int |
---|---|
Return type: | None |
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.
Return type: | int |
---|
Returns the period as set by set_motion_callback_period().
Parameters: | period -- int |
---|---|
Return type: | None |
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.
Return type: | int |
---|
Returns the period as set by set_date_time_callback_period().
Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the register_callback() function of the device object. The first parameter is the callback ID and the second parameter the callback function:
def my_callback(param):
print(param)
gps.register_callback(GPS.CALLBACK_EXAMPLE, my_callback)
The available constants with inherent number and type of parameters are described below.
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.
Parameters: |
|
---|
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().
Parameters: |
|
---|
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.
The following constants are available for this function:
Parameters: |
|
---|
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().
Parameters: |
|
---|
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().
Parameters: |
|
---|
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.
This constant is used to identify a GPS Bricklet.
The get_identity() function and the CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.