This is the description of the Shell API bindings for the Hall Effect Bricklet. General information and technical specifications for the Hall Effect 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 edge count without reset
tinkerforge call hall-effect-bricklet $uid get-edge-count false
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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 edge_count callback to 0.05s (50ms)
# note: the edge_count callback is only called every second if the
# edge_count has changed since the last call!
tinkerforge call hall-effect-bricklet $uid set-edge-count-callback-period 50
# handle incoming edge count callbacks
tinkerforge dispatch hall-effect-bricklet $uid edge-count
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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 Hall Effect Bricklet. It can take several options:
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The dispatch command is used to dispatch a callback of the Hall Effect 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 true if a magnetic field of 35 Gauss (3.5mT) or greater is detected.
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Returns the current value of the edge counter. You can configure edge type (rising, falling, both) that is counted with set-edge-count-config.
If you set the reset counter to true, the count is set back to 0 directly after it is read.
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Output: | no output |
The edge type parameter configures if rising edges, falling edges or both are counted. Possible edge types are:
A magnetic field of 35 Gauss (3.5mT) or greater causes a falling edge and a magnetic field of 25 Gauss (2.5mT) or smaller causes a rising edge.
If a magnet comes near the Bricklet the signal goes low (falling edge), if a magnet is removed from the vicinity the signal goes high (rising edge).
The debounce time is given in ms.
Configuring an edge counter resets its value to 0.
If you don't know what any of this means, just leave it at default. The default configuration is very likely OK for you.
Default values: 0 (edge type) and 100ms (debounce time)
The following symbols are available for this function:
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Returns the edge type and debounce time as set by set-edge-count-config.
The following symbols are available for this function:
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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 number of edges until an interrupt is invoked.
If edges is set to n, an interrupt is invoked for every n-th detected edge.
If edges is set to 0, the interrupt is disabled.
Default value is 0.
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Returns the edges as set by set-edge-interrupt.
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Output: | no output |
Sets the period in ms with which the edge-count callback is triggered periodically. A value of 0 turns the callback off.
edge-count is only triggered if the edge count has changed since the last triggering.
The default value is 0.
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Returns the period as set by set-edge-count-callback-period.
Callbacks can be used to receive time critical or recurring data from the device:
tinkerforge dispatch hall-effect-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-edge-count-callback-period. The parameters are the current count and the current value (see get-value and get-edge-count).
edge-count is only triggered if the count or value changed since the last triggering.