Note
This Bricklet is currently in the prototype stage and the software/hardware as well as the documentation is in an incomplete state.
This is the description of the Shell API bindings for the Laser Range Finder Bricklet. General information and technical specifications for the Laser Range Finder Bricklet are summarized in its hardware description.
An installation guide for the Shell 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 | #!/bin/sh
# connects to localhost:4223 by default, use --host and --port to change it
# change to your UID
uid=XYZ
# Turn laser on and wait 250ms for very first measurement to be ready
tinkerforge call laser-range-finder-bricklet $uid enable-laser
sleep 1
# get current distance (unit is cm/10)
tinkerforge call laser-range-finder-bricklet $uid get-distance
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Download (example-callback.sh)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | #!/bin/sh
# connects to localhost:4223 by default, use --host and --port to change it
# change to your UID
uid=XYZ
# Turn laser on and wait 250ms for very first measurement to be ready
tinkerforge call laser-range-finder-bricklet $uid enable-laser
sleep 1
# set period for distance callback to 1s (1000ms)
# note: the distance callback is only called every second if the
# distance has changed since the last call!
tinkerforge call laser-range-finder-bricklet $uid set-distance-callback-period 1000
# handle incoming distance callbacks (unit is cm)
tinkerforge dispatch laser-range-finder-bricklet $uid distance
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Download (example-threshold.sh)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | #!/bin/sh
# connects to localhost:4223 by default, use --host and --port to change it
# change to your UID
uid=XYZ
# Turn laser on and wait 250ms for very first measurement to be ready
tinkerforge call laser-range-finder-bricklet $uid enable-laser
sleep 1
# get threshold callbacks with a debounce time of 10 seconds (10000ms)
tinkerforge call laser-range-finder-bricklet $uid set-debounce-period 10000
# configure threshold for "greater than 20 cm" (unit is cm)
tinkerforge call laser-range-finder-bricklet $uid set-distance-callback-threshold greater 20 0
# handle incoming distance-reached callbacks (unit is cm)
tinkerforge dispatch laser-range-finder-bricklet $uid distance-reached\
--execute "echo Distance: {distance} cm"
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Possible exit codes for all tinkerforge commands are:
The common options of the call and dispatch commands are documented here. The specific command structure is shown below.
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The call command is used to call a function of the Laser Range Finder Bricklet. It can take several options:
Parameters: |
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The dispatch command is used to dispatch a callback of the Laser Range Finder Bricklet. It can take several options:
Parameters: |
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The <function> to be called can take different options depending of its kind. All functions can take the following options:
Getter functions can take the following options:
Setter functions can take the following options:
The --expect-response option for setter functions allows to detect timeouts and other error conditions calls of setters as well. The device will then send a response for this purpose. If this option is not given for a setter function then no response is send and errors are silently ignored, because they cannot be detected.
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The <callback> to be dispatched can take several options:
Output: |
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Returns the measured distance. The value has a range of 0 to 4000 and is given in cm.
The Laser Range Finder Bricklet knows different modes. Distances are only measured in the distance measurement mode, see set-mode. Also the laser has to be enabled, see enable-laser.
If you want to get the distance periodically, it is recommended to use the callback distance and set the period with set-distance-callback-period.
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Returns the measured velocity. The value has a range of 0 to 12700 and is given in 1/100 m/s.
The Laser Range Finder Bricklet knows different modes. Velocity is only measured in the velocity measurement modes, see set-mode. Also the laser has to be enabled, see enable-laser.
If you want to get the velocity periodically, it is recommended to use the callback velocity and set the period with set-velocity-callback-period.
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Output: | no output |
The LIDAR has five different modes. One mode is for distance measurements and four modes are for velocity measurements with different ranges.
The following modes are available:
The default mode is 0 (distance is measured).
The following symbols are available for this function:
Output: |
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Returns the mode as set by set-mode.
The following symbols are available for this function:
Output: | no output |
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Activates the laser of the LIDAR.
We recommend that you wait 250ms after enabling the laser before the first call of get-distance to ensure stable measurements.
Output: | no output |
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Deactivates the laser of the LIDAR.
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Returns true if the laser is enabled, false otherwise.
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Output: | no output |
Sets the length of a moving averaging for the distance and velocity.
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 0-30.
The default value is 10.
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Returns the length moving average as set by set-moving-average.
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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.
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Output: | no output |
Sets the period in ms with which the distance callback is triggered periodically. A value of 0 turns the callback off.
distance is only triggered if the distance value has changed since the last triggering.
The default value is 0.
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Returns the period as set by set-distance-callback-period.
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Output: | no output |
Sets the period in ms with which the velocity callback is triggered periodically. A value of 0 turns the callback off.
velocity is only triggered if the velocity value has changed since the last triggering.
The default value is 0.
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Returns the period as set by set-velocity-callback-period.
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Output: | no output |
Sets the thresholds for the distance-reached callback.
The following options are possible:
Option | Description |
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'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 symbols are available for this function:
Output: |
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Returns the threshold as set by set-distance-callback-threshold.
The following symbols are available for this function:
Parameters: |
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Output: | no output |
Sets the thresholds for the velocity-reached callback.
The following options are possible:
Option | Description |
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'x' | Callback is turned off |
'o' | Callback is triggered when the velocity is outside the min and max values |
'i' | Callback is triggered when the velocity is inside the min and max values |
'<' | Callback is triggered when the velocity is smaller than the min value (max is ignored) |
'>' | Callback is triggered when the velocity is greater than the min value (max is ignored) |
The default value is ('x', 0, 0).
The following symbols are available for this function:
Output: |
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Returns the threshold as set by set-velocity-callback-threshold.
The following symbols are available for this function:
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Output: | no output |
Sets the period in ms with which the threshold callbacks
are triggered, if the thresholds
keep being reached.
The default value is 100.
Output: |
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Returns the debounce period as set by set-debounce-period.
Callbacks can be used to receive time critical or recurring data from the device:
tinkerforge dispatch laser-range-finder-bricklet <uid> example
The available callbacks 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.
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This callback is triggered periodically with the period that is set by set-distance-callback-period. The parameter is the distance value of the sensor.
distance is only triggered if the distance value has changed since the last triggering.
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This callback is triggered periodically with the period that is set by set-velocity-callback-period. The parameter is the velocity value of the sensor.
velocity is only triggered if the velocity has changed since the last triggering.
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This callback is triggered when the threshold as set by set-distance-callback-threshold 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 set-debounce-period.
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This callback is triggered when the threshold as set by set-velocity-callback-threshold is reached. The parameter is the velocity value of the sensor.
If the threshold keeps being reached, the callback is triggered periodically with the period as set by set-debounce-period.