This is the description of the Shell 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 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 | #!/bin/sh
# connects to localhost:4223 by default, use --host and --port to change it
# change to your UID
uid=XYZ
# get current distance value
tinkerforge call distance-us-bricklet $uid get-distance-value
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Download (example-callback.sh)
1 2 3 4 5 6 7 8 9 10 11 12 13 | #!/bin/sh
# connects to localhost:4223 by default, use --host and --port to change it
# change to your UID
uid=XYZ
# set period for distance callback to 0.2s (200ms)
# note: the distance callback is only called every 200ms if the
# distance has changed since the last call!
tinkerforge call distance-us-bricklet $uid set-distance-callback-period 1000
# handle incoming distance callbacks (unit is mm)
tinkerforge dispatch distance-us-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 | #!/bin/sh
# connects to localhost:4223 by default, use --host and --port to change it
# change to your UID
uid=XYZ
# get threshold callbacks with a debounce time of 1 second (1000ms)
tinkerforge call distance-us-bricklet $uid set-debounce-period 1000
# configure threshold for "smaller than 200"
tinkerforge call distance-us-bricklet $uid set-distance-callback-threshold smaller 200 0
# handle incoming distance-reached callbacks
tinkerforge dispatch distance-us-bricklet $uid distance-reached\
--execute "echo Distance Value is smaller than 200: {distance}"
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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 Distance US Bricklet. It can take several options:
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The dispatch command is used to dispatch a callback of the Distance US Bricklet. 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 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 distance and set the period with set-distance-callback-period.
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Output: | no output |
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.
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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 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:
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Returns the threshold as set by set-distance-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.
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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 distance-us-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 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.