This is the description of the MQTT API bindings for the Joystick Bricklet. General information and technical specifications for the Joystick Bricklet are summarized in its hardware description.
An installation guide for the MQTT API bindings is part of their general description.
The example code below is Public Domain (CC0 1.0).
1 2 3 4 5 6 | # Change XYZ to the UID of your Joystick Bricklet
setup:
# Get current position
subscribe to tinkerforge/response/joystick_bricklet/XYZ/get_position
publish '' to tinkerforge/request/joystick_bricklet/XYZ/get_position
|
Download (example-callback.txt)
1 2 3 4 5 6 7 8 9 10 | # Change XYZ to the UID of your Joystick Bricklet
setup:
# Handle incoming pressed callbacks
subscribe to tinkerforge/callback/joystick_bricklet/XYZ/pressed
publish '{"register": true}' to tinkerforge/register/joystick_bricklet/XYZ/pressed # Register pressed callback
# Handle incoming released callbacks
subscribe to tinkerforge/callback/joystick_bricklet/XYZ/released
publish '{"register": true}' to tinkerforge/register/joystick_bricklet/XYZ/released # Register released callback
|
Download (example-find-borders.txt)
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 | # Change XYZ to the UID of your Joystick Bricklet
setup:
# Get threshold callbacks with a debounce time of 0.2 seconds (200ms)
publish '{"debounce": 200}' to tinkerforge/request/joystick_bricklet/XYZ/set_debounce_period
# Handle incoming position reached callbacks
subscribe to tinkerforge/callback/joystick_bricklet/XYZ/position_reached
if a message arrives
# message contains x and y as int
if y == 100
print "Top"
elseif y == -100
print "Bottom"
endif
if x == 100
print "Right"
elseif x == -100
print "Left"
endif
print "\n"
endif
endsubscribe
publish '{"register": true}' to tinkerforge/register/joystick_bricklet/XYZ/position_reached # Register position_reached callback
# Configure threshold for position "outside of -99, -99 to 99, 99"
publish '{"option": "outside", "min_x": -99, "max_x": 99, "min_y": -99, "max_y": 99}' to tinkerforge/request/joystick_bricklet/XYZ/set_position_callback_threshold
|
All published payloads to and from the MQTT bindings are in JSON format.
If an error occures, the bindings publish a JSON object containing the error message as member _ERROR
.
It is published on the corresponding response topic: .../response/...
for .../request/...
and .../callback/...
for .../register/...
.
request/
joystick_bricklet/
<UID>/
get_position
¶Request: |
|
---|---|
Response: |
|
Returns the position of the joystick. The middle position of the joystick is x=0, y=0.
The returned values are averaged and calibrated (see request/joystick_bricklet/<UID>/calibrate
).
If you want to get the position periodically, it is recommended to use the
register/joystick_bricklet/<UID>/position
callback and set the period with
request/joystick_bricklet/<UID>/set_position_callback_period
.
request/
joystick_bricklet/
<UID>/
is_pressed
¶Request: |
|
---|---|
Response: |
|
Returns true if the button is pressed and false otherwise.
It is recommended to use the register/joystick_bricklet/<UID>/pressed
and register/joystick_bricklet/<UID>/released
callbacks
to handle the button.
request/
joystick_bricklet/
<UID>/
get_analog_value
¶Request: |
|
---|---|
Response: |
|
Returns the values as read by a 12-bit analog-to-digital converter.
Note
The values returned by request/joystick_bricklet/<UID>/get_position
are averaged over several samples
to yield less noise, while request/joystick_bricklet/<UID>/get_analog_value
gives back raw
unfiltered analog values. The only reason to use request/joystick_bricklet/<UID>/get_analog_value
is,
if you need the full resolution of the analog-to-digital converter.
If you want the analog values periodically, it is recommended to use the
register/joystick_bricklet/<UID>/analog_value
callback and set the period with
request/joystick_bricklet/<UID>/set_analog_value_callback_period
.
request/
joystick_bricklet/
<UID>/
calibrate
¶Request: |
|
---|---|
Response: |
|
Calibrates the middle position of the joystick. If your Joystick Bricklet does not return x=0 and y=0 in the middle position, call this function while the joystick is standing still in the middle position.
The resulting calibration will be saved on the EEPROM of the Joystick Bricklet, thus you only have to calibrate it once.
request/
joystick_bricklet/
<UID>/
get_identity
¶Request: |
|
---|---|
Response: |
|
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. If symbolic output is not disabled, the device identifier is mapped to the corresponding name in the format used in topics.
The display name contains the Joystick's name in a human readable form.
request/
joystick_bricklet/
<UID>/
set_position_callback_period
¶Request: |
|
---|---|
Response: |
|
Sets the period with which the register/joystick_bricklet/<UID>/position
callback is triggered
periodically. A value of 0 turns the callback off.
The register/joystick_bricklet/<UID>/position
callback is only triggered if the position has changed since the
last triggering.
request/
joystick_bricklet/
<UID>/
get_position_callback_period
¶Request: |
|
---|---|
Response: |
|
Returns the period as set by request/joystick_bricklet/<UID>/set_position_callback_period
.
request/
joystick_bricklet/
<UID>/
set_analog_value_callback_period
¶Request: |
|
---|---|
Response: |
|
Sets the period with which the register/joystick_bricklet/<UID>/analog_value
callback is triggered
periodically. A value of 0 turns the callback off.
The register/joystick_bricklet/<UID>/analog_value
callback is only triggered if the analog values have
changed since the last triggering.
request/
joystick_bricklet/
<UID>/
get_analog_value_callback_period
¶Request: |
|
---|---|
Response: |
|
Returns the period as set by request/joystick_bricklet/<UID>/set_analog_value_callback_period
.
request/
joystick_bricklet/
<UID>/
set_position_callback_threshold
¶Request: |
|
---|---|
Response: |
|
Sets the thresholds for the register/joystick_bricklet/<UID>/position_reached
callback.
The following options are possible:
Option | Description |
---|---|
'x' | Callback is turned off |
'o' | Callback is triggered when the position is outside the min and max values |
'i' | Callback is triggered when the position is inside the min and max values |
'<' | Callback is triggered when the position is smaller than the min values (max is ignored) |
'>' | Callback is triggered when the position is greater than the min values (max is ignored) |
The following symbols are available for this function:
For option:
request/
joystick_bricklet/
<UID>/
get_position_callback_threshold
¶Request: |
|
---|---|
Response: |
|
Returns the threshold as set by request/joystick_bricklet/<UID>/set_position_callback_threshold
.
The following symbols are available for this function:
For option:
request/
joystick_bricklet/
<UID>/
set_analog_value_callback_threshold
¶Request: |
|
---|---|
Response: |
|
Sets the thresholds for the register/joystick_bricklet/<UID>/analog_value_reached
callback.
The following options are possible:
Option | Description |
---|---|
'x' | Callback is turned off |
'o' | Callback is triggered when the analog values are outside the min and max values |
'i' | Callback is triggered when the analog values are inside the min and max values |
'<' | Callback is triggered when the analog values are smaller than the min values (max is ignored) |
'>' | Callback is triggered when the analog values are greater than the min values (max is ignored) |
The following symbols are available for this function:
For option:
request/
joystick_bricklet/
<UID>/
get_analog_value_callback_threshold
¶Request: |
|
---|---|
Response: |
|
Returns the threshold as set by request/joystick_bricklet/<UID>/set_analog_value_callback_threshold
.
The following symbols are available for this function:
For option:
request/
joystick_bricklet/
<UID>/
set_debounce_period
¶Request: |
|
---|---|
Response: |
|
Sets the period with which the threshold callbacks
register/joystick_bricklet/<UID>/position_reached
,register/joystick_bricklet/<UID>/analog_value_reached
are triggered, if the thresholds
request/joystick_bricklet/<UID>/set_position_callback_threshold
,request/joystick_bricklet/<UID>/set_analog_value_callback_threshold
keep being reached.
request/
joystick_bricklet/
<UID>/
get_debounce_period
¶Request: |
|
---|---|
Response: |
|
Returns the debounce period as set by request/joystick_bricklet/<UID>/set_debounce_period
.
Callbacks can be registered to receive
time critical or recurring data from the device. The registration is done
with the corresponding .../register/...
topic and an optional suffix.
This suffix 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.
register/
joystick_bricklet/
<UID>/
position
¶Register Request: |
|
---|---|
Callback Response: |
|
A callback can be registered for this event by publishing to the .../register/joystick_bricklet/<UID>/position[/<SUFFIX>]
topic with the payload "true".
An added callback can be removed by publishing to the same topic with the payload "false".
To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.
If the callback is triggered, a message with it's payload is published under the corresponding .../callback/joystick_bricklet/<UID>/position[/<SUFFIX>]
topic for each registered suffix.
This callback is triggered periodically with the period that is set by
request/joystick_bricklet/<UID>/set_position_callback_period
. The callback payload is the position of the
joystick.
The register/joystick_bricklet/<UID>/position
callback is only triggered if the position has changed since the
last triggering.
register/
joystick_bricklet/
<UID>/
analog_value
¶Register Request: |
|
---|---|
Callback Response: |
|
A callback can be registered for this event by publishing to the .../register/joystick_bricklet/<UID>/analog_value[/<SUFFIX>]
topic with the payload "true".
An added callback can be removed by publishing to the same topic with the payload "false".
To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.
If the callback is triggered, a message with it's payload is published under the corresponding .../callback/joystick_bricklet/<UID>/analog_value[/<SUFFIX>]
topic for each registered suffix.
This callback is triggered periodically with the period that is set by
request/joystick_bricklet/<UID>/set_analog_value_callback_period
. The callback payload members are the
analog values of the joystick.
The register/joystick_bricklet/<UID>/analog_value
callback is only triggered if the values have changed
since the last triggering.
register/
joystick_bricklet/
<UID>/
position_reached
¶Register Request: |
|
---|---|
Callback Response: |
|
A callback can be registered for this event by publishing to the .../register/joystick_bricklet/<UID>/position_reached[/<SUFFIX>]
topic with the payload "true".
An added callback can be removed by publishing to the same topic with the payload "false".
To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.
If the callback is triggered, a message with it's payload is published under the corresponding .../callback/joystick_bricklet/<UID>/position_reached[/<SUFFIX>]
topic for each registered suffix.
This callback is triggered when the threshold as set by
request/joystick_bricklet/<UID>/set_position_callback_threshold
is reached.
The callback payload members are the position of the joystick.
If the threshold keeps being reached, the callback is triggered periodically
with the period as set by request/joystick_bricklet/<UID>/set_debounce_period
.
register/
joystick_bricklet/
<UID>/
analog_value_reached
¶Register Request: |
|
---|---|
Callback Response: |
|
A callback can be registered for this event by publishing to the .../register/joystick_bricklet/<UID>/analog_value_reached[/<SUFFIX>]
topic with the payload "true".
An added callback can be removed by publishing to the same topic with the payload "false".
To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.
If the callback is triggered, a message with it's payload is published under the corresponding .../callback/joystick_bricklet/<UID>/analog_value_reached[/<SUFFIX>]
topic for each registered suffix.
This callback is triggered when the threshold as set by
request/joystick_bricklet/<UID>/set_analog_value_callback_threshold
is reached.
The callback payload members are the analog values of the joystick.
If the threshold keeps being reached, the callback is triggered periodically
with the period as set by request/joystick_bricklet/<UID>/set_debounce_period
.
register/
joystick_bricklet/
<UID>/
pressed
¶Register Request: |
|
---|---|
Callback Response: |
|
A callback can be registered for this event by publishing to the .../register/joystick_bricklet/<UID>/pressed[/<SUFFIX>]
topic with the payload "true".
An added callback can be removed by publishing to the same topic with the payload "false".
To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.
If the callback is triggered, a message with it's payload is published under the corresponding .../callback/joystick_bricklet/<UID>/pressed[/<SUFFIX>]
topic for each registered suffix.
This callback is triggered when the button is pressed.
register/
joystick_bricklet/
<UID>/
released
¶Register Request: |
|
---|---|
Callback Response: |
|
A callback can be registered for this event by publishing to the .../register/joystick_bricklet/<UID>/released[/<SUFFIX>]
topic with the payload "true".
An added callback can be removed by publishing to the same topic with the payload "false".
To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.
If the callback is triggered, a message with it's payload is published under the corresponding .../callback/joystick_bricklet/<UID>/released[/<SUFFIX>]
topic for each registered suffix.
This callback is triggered when the button is released.