This is the description of the Shell API bindings for the Distance IR Bricklet. General information and technical specifications for the Distance IR 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 (unit is mm)
tinkerforge call distance-ir-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 | #!/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-ir-bricklet $uid set-distance-callback-period 1000
# handle incoming distance callbacks (unit is mm)
tinkerforge dispatch distance-ir-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-ir-bricklet $uid set-debounce-period 1000
# configure threshold for "smaller than 20cm" (unit is mm)
tinkerforge call distance-ir-bricklet $uid set-distance-callback-threshold smaller 200 0
# handle incoming distance-reached callbacks (unit is mm)
tinkerforge dispatch distance-ir-bricklet $uid distance-reached\
--execute "echo Distance is smaller than 20cm: {distance} mm"
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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 IR Bricklet. It can take several options:
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The dispatch command is used to dispatch a callback of the Distance IR 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 distance measured by the sensor. The value is in mm and possible distance ranges are 40 to 300, 100 to 800 and 200 to 1500, depending on the selected IR sensor.
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 value as read by a 12-bit analog-to-digital converter. The value is between 0 and 4095.
Note
The value returned by get-distance is averaged over several samples to yield less noise, while get-analog-value gives back raw unfiltered analog values. The only reason to use get-analog-value is, if you need the full resolution of the analog-to-digital converter.
If you want the analog value periodically, it is recommended to use the callback analog-value and set the period with set-analog-value-callback-period.
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Output: | no output |
Sets a sampling point value to a specific position of the lookup table. The lookup table comprises 128 equidistant analog values with corresponding distances.
If you measure a distance of 50cm at the analog value 2048, you should call this function with (64, 5000). The utilized analog-to-digital converter has a resolution of 12 bit. With 128 sampling points on the whole range, this means that every sampling point has a size of 32 analog values. Thus the analog value 2048 has the corresponding sampling point 64 = 2048/32.
Sampling points are saved on the EEPROM of the Distance IR Bricklet and loaded again on startup.
Note
An easy way to calibrate the sampling points of the Distance IR Bricklet is implemented in the Brick Viewer. If you want to calibrate your Bricklet it is highly recommended to use this implementation.
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Returns the distance to a sampling point position as set by set-sampling-point.
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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 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 analog-value callback is triggered periodically. A value of 0 turns the callback off.
analog-value is only triggered if the analog value has changed since the last triggering.
The default value is 0.
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Returns the period as set by set-analog-value-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 is outside the min and max values |
'i' | Callback is triggered when the distance is inside the min and max values |
'<' | Callback is triggered when the distance is smaller than the min value (max is ignored) |
'>' | Callback is triggered when the distance 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 thresholds for the analog-value-reached callback.
The following options are possible:
Option | Description |
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'x' | Callback is turned off |
'o' | Callback is triggered when the analog value is outside the min and max values |
'i' | Callback is triggered when the analog value is inside the min and max values |
'<' | Callback is triggered when the analog value is smaller than the min value (max is ignored) |
'>' | Callback is triggered when the analog 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-analog-value-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-ir-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 of the sensor.
distance is only triggered if the distance has changed since the last triggering.
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This callback is triggered periodically with the period that is set by set-analog-value-callback-period. The parameter is the analog value of the sensor.
analog-value is only triggered if the analog 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 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-analog-value-callback-threshold is reached. The parameter is the analog value of the sensor.
If the threshold keeps being reached, the callback is triggered periodically with the period as set by set-debounce-period.