This is the description of the Shell API bindings for the Laser Range Finder Bricklet 2.0. General information and technical specifications for the Laser Range Finder Bricklet 2.0 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).
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 2.0. It can take several options:
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The dispatch command is used to dispatch a callback of the Laser Range Finder Bricklet 2.0. It can take several options:
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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:
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Returns the measured distance.
The laser has to be enabled, see set-enable.
If you want to get the value periodically, it is recommended to use the distance callback. You can set the callback configuration with set-distance-callback-configuration.
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Returns the measured velocity. The value has a range of -12800 to 12700 and is given in 1/100 m/s.
The velocity measurement only produces stables results if a fixed measurement rate (see set-configuration) is configured. Also the laser has to be enabled, see set-enable.
If you want to get the value periodically, it is recommended to use the velocity callback. You can set the callback configuration with set-velocity-callback-configuration.
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Enables the laser of the LIDAR if set to true.
We recommend that you wait 250ms after enabling the laser before the first call of get-distance to ensure stable measurements.
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Returns the value as set by set-enable.
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The Acquisition Count defines the number of times the Laser Range Finder Bricklet will integrate acquisitions to find a correlation record peak. With a higher count, the Bricklet can measure longer distances. With a lower count, the rate increases. The allowed values are 1-255.
If you set Enable Quick Termination to true, the distance measurement will be terminated early if a high peak was already detected. This means that a higher measurement rate can be achieved and long distances can be measured at the same time. However, the chance of false-positive distance measurements increases.
Normally the distance is calculated with a detection algorithm that uses peak value, signal strength and noise. You can however also define a fixed Threshold Value. Set this to a low value if you want to measure the distance to something that has very little reflection (e.g. glass) and set it to a high value if you want to measure the distance to something with a very high reflection (e.g. mirror). Set this to 0 to use the default algorithm. The other allowed values are 1-255.
Set the Measurement Frequency to force a fixed measurement rate. If set to 0, the Laser Range Finder Bricklet will use the optimal frequency according to the other configurations and the actual measured distance. Since the rate is not fixed in this case, the velocity measurement is not stable. For a stable velocity measurement you should set a fixed measurement frequency. The lower the frequency, the higher is the resolution of the calculated velocity. The allowed values are 10Hz-500Hz (and 0 to turn the fixed frequency off).
The default values for Acquisition Count, Enable Quick Termination, Threshold Value and Measurement Frequency are 128, false, 0 and 0.
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Returns the configuration as set by set-configuration.
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Configures the distance LED to be either turned off, turned on, blink in heartbeat mode or show the distance (brighter = object is nearer).
The following symbols are available for this function:
For <config>:
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Returns the LED configuration as set by set-distance-led-config
The following symbols are available for this function:
For config:
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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.
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Returns the length moving average as set by set-moving-average.
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The offset is added to the measured distance. It is saved in non-volatile memory, you only have to set it once.
The Bricklet comes with a per-sensor factory-calibrated offset value, you should not have to call this function.
If you want to re-calibrate the offset you first have to set it to 0. Calculate the offset by measuring the distance to a known distance and set it again.
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Returns the offset value as set by set-offset-calibration.
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Returns the error count for the communication between Brick and Bricklet.
The errors are divided into
The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.
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Sets the bootloader mode and returns the status after the requested mode change was instigated.
You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.
This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.
The following symbols are available for this function:
For <mode>:
For status:
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Returns the current bootloader mode, see set-bootloader-mode.
The following symbols are available for this function:
For mode:
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Sets the firmware pointer for write-firmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).
This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.
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Writes 64 Bytes of firmware at the position as written by set-write-firmware-pointer before. The firmware is written to flash every 4 chunks.
You can only write firmware in bootloader mode.
This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.
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Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.
You can also turn the LED permanently on/off or show a heartbeat.
If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.
The following symbols are available for this function:
For <config>:
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Returns the configuration as set by set-status-led-config
The following symbols are available for this function:
For config:
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Returns the temperature as measured inside the microcontroller. The value returned is not the ambient temperature!
The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.
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Calling this function will reset the Bricklet. All configurations will be lost.
After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!
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Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.
We recommend that you use Brick Viewer to change the UID.
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Returns the current UID as an integer. Encode as Base58 to get the usual string version.
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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', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). The Raspberry Pi HAT (Zero) Brick is always at position 'i' and the Bricklet connected to an Isolator Bricklet is always as position 'z'.
The device identifier numbers can be found here.
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The period is the period with which the distance callback is triggered periodically. A value of 0 turns the callback off.
If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.
If it is set to false, the callback is continuously triggered with the period, independent of the value.
It is furthermore possible to constrain the callback with thresholds.
The option-parameter together with min/max sets a threshold for the distance callback.
The following options are possible:
Option | Description |
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'x' | Threshold is turned off |
'o' | Threshold is triggered when the value is outside the min and max values |
'i' | Threshold is triggered when the value is inside or equal to the min and max values |
'<' | Threshold is triggered when the value is smaller than the min value (max is ignored) |
'>' | Threshold is triggered when the value is greater than the min value (max is ignored) |
If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.
The following symbols are available for this function:
For <option>:
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Returns the callback configuration as set by set-distance-callback-configuration.
The following symbols are available for this function:
For option:
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The period is the period with which the velocity callback is triggered periodically. A value of 0 turns the callback off.
If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.
If it is set to false, the callback is continuously triggered with the period, independent of the value.
It is furthermore possible to constrain the callback with thresholds.
The option-parameter together with min/max sets a threshold for the velocity callback.
The following options are possible:
Option | Description |
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'x' | Threshold is turned off |
'o' | Threshold is triggered when the value is outside the min and max values |
'i' | Threshold is triggered when the value is inside or equal to the min and max values |
'<' | Threshold is triggered when the value is smaller than the min value (max is ignored) |
'>' | Threshold is triggered when the value is greater than the min value (max is ignored) |
If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.
The following symbols are available for this function:
For <option>:
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Returns the callback configuration as set by set-velocity-callback-configuration.
The following symbols are available for this function:
For option:
Callbacks can be used to receive time critical or recurring data from the device:
tinkerforge dispatch laser-range-finder-v2-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 according to the configuration set by set-distance-callback-configuration.
The parameter is the same as get-distance.
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This callback is triggered periodically according to the configuration set by set-velocity-callback-configuration.
The parameter is the same as get-velocity.