This is the description of the MATLAB/Octave API bindings for the Distance US Bricklet. General information and technical specifications for the Distance US Bricklet are summarized in its hardware description.
An installation guide for the MATLAB/Octave API bindings is part of their general description.
The example code below is Public Domain (CC0 1.0).
Download (matlab_example_simple.m)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | function matlab_example_simple()
import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletDistanceUS;
HOST = 'localhost';
PORT = 4223;
UID = 'mYj'; % Change to your UID
ipcon = IPConnection(); % Create IP connection
dist = BrickletDistanceUS(UID, ipcon); % Create device object
ipcon.connect(HOST, PORT); % Connect to brickd
% Don't use device before ipcon is connected
% Get current distance value
distance = dist.getDistanceValue();
fprintf('Distance Value: %g\n', distance);
input('Press any key to exit...\n', 's');
ipcon.disconnect();
end
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Download (matlab_example_callback.m)
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 | function matlab_example_callback()
import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletDistanceUS;
HOST = 'localhost';
PORT = 4223;
UID = 'mYj'; % Change to your UID
ipcon = IPConnection(); % Create IP connection
dist = BrickletDistanceUS(UID, ipcon); % Create device object
ipcon.connect(HOST, PORT); % Connect to brickd
% Don't use device before ipcon is connected
% Set Period for distance callback to 0.2s (200ms)
% Note: The callback is only called every 200ms if the
% distance has changed since the last call!
dist.setDistanceCallbackPeriod(200);
% Register distance callback to function cb_distance
set(dist, 'DistanceCallback', @(h, e) cb_distance(e));
input('Press any key to exit...\n', 's');
ipcon.disconnect();
end
% Callback function for distance value
function cb_distance(e)
fprintf('Distance Value: %g\n', e.distance);
end
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Download (matlab_example_threshold.m)
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 | function matlab_example_threshold()
import com.tinkerforge.IPConnection;
import com.tinkerforge.BrickletDistanceUS;
HOST = 'localhost';
PORT = 4223;
UID = 'mYj'; % Change to your UID
ipcon = IPConnection(); % Create IP connection
dist = BrickletDistanceUS(UID, ipcon); % Create device object
ipcon.connect(HOST, PORT); % Connect to brickd
% Don't use device before ipcon is connected
% Get threshold callbacks with a debounce time of 10 seconds (10000ms)
dist.setDebouncePeriod(10000);
% Register threshold reached callback to function cb_reached
set(dist, 'DistanceReachedCallback', @(h, e) cb_reached(e));
% Configure threshold for "smaller than 200"
dist.setDistanceCallbackThreshold('<', 200, 0);
input('Press any key to exit...\n', 's');
ipcon.disconnect();
end
% Callback for distance value smaller than 200
function cb_reached(e)
fprintf('Distance Value is smaller than 200: %g\n', e.distance);
end
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Download (octave_example_simple.m)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | function octave_example_simple()
more off;
HOST = "localhost";
PORT = 4223;
UID = "mYj"; % Change to your UID
ipcon = java_new("com.tinkerforge.IPConnection"); % Create IP connection
dist = java_new("com.tinkerforge.BrickletDistanceUS", UID, ipcon); % Create device object
ipcon.connect(HOST, PORT); % Connect to brickd
% Don't use device before ipcon is connected
% Get current distance value
distance = dist.getDistanceValue();
fprintf("Distance Value: %g\n", distance);
input("Press any key to exit...\n", "s");
ipcon.disconnect();
end
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Download (octave_example_callback.m)
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 | function octave_example_callback()
more off;
HOST = "localhost";
PORT = 4223;
UID = "mYj"; % Change to your UID
ipcon = java_new("com.tinkerforge.IPConnection"); % Create IP connection
dist = java_new("com.tinkerforge.BrickletDistanceUS", UID, ipcon); % Create device object
ipcon.connect(HOST, PORT); % Connect to brickd
% Don't use device before ipcon is connected
% Set Period for distance callback to 0.2s (200ms)
% Note: The callback is only called every 200ms if the
% distance has changed since the last call!
dist.setDistanceCallbackPeriod(200);
% Register distance callback to function cb_distance
dist.addDistanceCallback(@cb_distance);
input("Press any key to exit...\n", "s");
ipcon.disconnect();
end
% Callback function for distance value
function cb_distance(e)
fprintf("Distance Value: %g\n", e.distance);
end
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Download (octave_example_threshold.m)
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 | function octave_example_threshold()
more off;
HOST = "localhost";
PORT = 4223;
UID = "mYj"; % Change to your UID
ipcon = java_new("com.tinkerforge.IPConnection"); % Create IP connection
dist = java_new("com.tinkerforge.BrickletDistanceUS", UID, ipcon); % Create device object
ipcon.connect(HOST, PORT); % Connect to brickd
% Don"t use device before ipcon is connected
% Get threshold callbacks with a debounce time of 10 seconds (10000ms)
dist.setDebouncePeriod(10000);
% Register threshold reached callback to function cb_reached
dist.addDistanceCallback(@cb_reached);
% Configure threshold for "smaller than 200"
dist.setDistanceCallbackThreshold("<", 200, 0);
input("Press any key to exit...\n", "s");
ipcon.disconnect();
end
% Callback for distance value smaller than 200
function cb_reached(e)
fprintf("Distance Value is smaller than 200: %g\n", e.distance);
end
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Generally, every method of the MATLAB bindings that returns a value can throw a TimeoutException. This exception gets thrown if the device did not respond. If a cable based connection is used, it is unlikely that this exception gets thrown (assuming nobody unplugs the device). However, if a wireless connection is used, timeouts will occur if the distance to the device gets too big.
Beside the TimeoutException there is also a NotConnectedException that is thrown if a method needs to communicate with the device while the IP Connection is not connected.
Since the MATLAB bindings are based on Java and Java does not support multiple return values and return by reference is not possible for primitive types, we use small classes that only consist of member variables. The member variables of the returned objects are described in the corresponding method descriptions.
The package for all Brick/Bricklet bindings and the IP Connection is com.tinkerforge.*
All methods listed below are thread-safe.
Creates an object with the unique device ID uid.
In MATLAB:
import com.tinkerforge.BrickletDistanceUS;
distanceUS = BrickletDistanceUS('YOUR_DEVICE_UID', ipcon);
In Octave:
distanceUS = java_new("com.tinkerforge.BrickletDistanceUS", "YOUR_DEVICE_UID", ipcon);
This object can then be used after the IP Connection is connected (see examples above).
Returns the current distance value measured by the sensor. The value has a range of 0 to 4095. A small value corresponds to a small distance, a big value corresponds to a big distance. The relation between the measured distance value and the actual distance is affected by the 5V supply voltage (deviations in the supply voltage result in deviations in the distance values) and is non-linear (resolution is bigger at close range).
If you want to get the distance value periodically, it is recommended to use the callback DistanceCallback and set the period with setDistanceCallbackPeriod().
Sets the length of a moving averaging for the distance value.
Setting the length to 0 will turn the averaging completely off. With less averaging, there is more noise on the data.
The range for the averaging is 0-100.
The default value is 20.
Returns the length moving average as set by setMovingAverage().
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.
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 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 setResponseExpected() for the list of function ID constants available for this function.
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:
Changes the response expected flag for all setter and callback configuration functions of this device at once.
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 object has the public member variables String uid, String connectedUid, char position, short[] hardwareVersion, short[] firmwareVersion and int deviceIdentifier.
Sets the period in ms with which the DistanceCallback callback is triggered periodically. A value of 0 turns the callback off.
DistanceCallback is only triggered if the distance value has changed since the last triggering.
The default value is 0.
Returns the period as set by setDistanceCallbackPeriod().
Sets the thresholds for the DistanceReachedCallback callback.
The following options are possible:
Option | Description |
---|---|
'x' | Callback is turned off |
'o' | Callback is triggered when the distance value is outside the min and max values |
'i' | Callback is triggered when the distance value is inside the min and max values |
'<' | Callback is triggered when the distance value is smaller than the min value (max is ignored) |
'>' | Callback is triggered when the distance value is greater than the min value (max is ignored) |
The default value is ('x', 0, 0).
The following constants are available for this function:
Returns the threshold as set by setDistanceCallbackThreshold().
The following constants are available for this function:
The returned object has the public member variables char option, short min and short max.
Sets the period in ms with which the threshold callbacks
are triggered, if the thresholds
keep being reached.
The default value is 100.
Returns the debounce period as set by setDebouncePeriod().
Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with "set" function of MATLAB. The parameters consist of the IP Connection object, the callback name and the callback function. For example, it looks like this in MATLAB:
function cb_example(e)
fprintf('Parameter: %s\n', e.param);
end
set(device, 'ExampleCallback', @(h, e) cb_example(e));
Due to a difference in the Octave Java support the "set" function cannot be used in Octave. The registration is done with "add*Callback" functions of the device object. It looks like this in Octave:
function cb_example(e)
fprintf("Parameter: %s\n", e.param);
end
device.addExampleCallback(@cb_example);
It is possible to add several callbacks and to remove them with the corresponding "remove*Callback" function.
The parameters of the callback are passed to the callback function as fields of the structure e, which is derived from the java.util.EventObject class. The available callback names with corresponding structure fields 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: | distance -- int |
---|
This callback is triggered periodically with the period that is set by setDistanceCallbackPeriod(). The parameter is the distance value of the sensor.
DistanceCallback is only triggered if the distance value has changed since the last triggering.
In MATLAB the set() function can be used to register a callback function to this callback.
In Octave a callback function can be added to this callback using the addDistanceCallback() function. An added callback function can be removed with the removeDistanceCallback() function.
Parameters: | distance -- int |
---|
This callback is triggered when the threshold as set by setDistanceCallbackThreshold() is reached. The parameter is the distance value of the sensor.
If the threshold keeps being reached, the callback is triggered periodically with the period as set by setDebouncePeriod().
In MATLAB the set() function can be used to register a callback function to this callback.
In Octave a callback function can be added to this callback using the addDistanceReachedCallback() function. An added callback function can be removed with the removeDistanceReachedCallback() function.
This constant is used to identify a Distance US Bricklet.
The getIdentity() function and the EnumerateCallback callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.