Software / API Bindings / JavaScript / API Reference and Examples / Bricklets / Hall Effect Bricklet

JavaScript - Hall Effect Bricklet¶

This is the description of the JavaScript 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 JavaScript API bindings is part of their general description.

Examples¶

The example code below is Public Domain (CC0 1.0).

Simple (Node.js)¶

Download (ExampleSimple.js)

var Tinkerforge = require('tinkerforge');

var HOST = 'localhost';
var PORT = 4223;
var UID = 'XYZ'; // Change XYZ to the UID of your Hall Effect Bricklet

var ipcon = new Tinkerforge.IPConnection(); // Create IP connection
var he = new Tinkerforge.BrickletHallEffect(UID, ipcon); // Create device object

ipcon.connect(HOST, PORT,
    function (error) {
        console.log('Error: ' + error);
    }
); // Connect to brickd
// Don't use device before ipcon is connected

ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
    function (connectReason) {
        // Get current edge count without reset
        he.getEdgeCount(false,
            function (count) {
                console.log('Count: ' + count);
            },
            function (error) {
                console.log('Error: ' + error);
            }
        );
    }
);

console.log('Press key to exit');
process.stdin.on('data',
    function (data) {
        ipcon.disconnect();
        process.exit(0);
    }
);

Callback (Node.js)¶

Download (ExampleCallback.js)

var Tinkerforge = require('tinkerforge');

var HOST = 'localhost';
var PORT = 4223;
var UID = 'XYZ'; // Change XYZ to the UID of your Hall Effect Bricklet

var ipcon = new Tinkerforge.IPConnection(); // Create IP connection
var he = new Tinkerforge.BrickletHallEffect(UID, ipcon); // Create device object

ipcon.connect(HOST, PORT,
    function (error) {
        console.log('Error: ' + error);
    }
); // Connect to brickd
// Don't use device before ipcon is connected

ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
    function (connectReason) {
        // Set period for edge count callback to 0.05s (50ms)
        // Note: The edge count callback is only called every 0.05 seconds
        //       if the edge count has changed since the last call!
        he.setEdgeCountCallbackPeriod(50);
    }
);

// Register edge count callback
he.on(Tinkerforge.BrickletHallEffect.CALLBACK_EDGE_COUNT,
    // Callback function for edge count callback
    function (count, value) {
        console.log('Count: ' + count);
    }
);

console.log('Press key to exit');
process.stdin.on('data',
    function (data) {
        ipcon.disconnect();
        process.exit(0);
    }
);

Simple (HTML)¶

Download (ExampleSimple.html), Test (ExampleSimple.html)

<!DOCTYPE html>
<html>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <head>
        <title>Tinkerforge | JavaScript Example</title>
    </head>
    <body>
        <div style="text-align:center;">
            <h1>Hall Effect Bricklet Simple Example</h1>
            <p>
                <input value="localhost" id="host" type="text" size="20">:
                <input value="4280" id="port" type="text" size="5">,
                <input value="uid" id="uid" type="text" size="5">
                <input value="Start Example" id="start" type="button" onclick="startExample();">
            </p>
            <p>
                <textarea readonly id="text" cols="80" rows="24" style="resize:none;"
                          >Press "Start Example" to begin ...</textarea>
            </p>
        </div>
        <script src="./Tinkerforge.js" type='text/javascript'></script>
        <script type='text/javascript'>
            var ipcon;
            var textArea = document.getElementById("text");
            function startExample() {
                textArea.value = "";
                var HOST = document.getElementById("host").value;
                var PORT = parseInt(document.getElementById("port").value);
                var UID = document.getElementById("uid").value;
                if(ipcon !== undefined) {
                    ipcon.disconnect();
                }
                ipcon = new Tinkerforge.IPConnection(); // Create IP connection
                var he = new Tinkerforge.BrickletHallEffect(UID, ipcon); // Create device object
                ipcon.connect(HOST, PORT,
                    function(error) {
                        textArea.value += 'Error: ' + error + '\n';
                    }
                ); // Connect to brickd
                // Don't use device before ipcon is connected

                ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
                    function (connectReason) {
                        // Get current edge count without reset
                        he.getEdgeCount(false,
                            function (count) {
                                textArea.value += 'Count: ' + count + '\n';
                            },
                            function (error) {
                                textArea.value += 'Error: ' + error + '\n';
                            }
                        );
                    }
                );
            }
        </script>
    </body>
</html>

Callback (HTML)¶

Download (ExampleCallback.html), Test (ExampleCallback.html)

<!DOCTYPE html>
<html>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <head>
        <title>Tinkerforge | JavaScript Example</title>
    </head>
    <body>
        <div style="text-align:center;">
            <h1>Hall Effect Bricklet Callback Example</h1>
            <p>
                <input value="localhost" id="host" type="text" size="20">:
                <input value="4280" id="port" type="text" size="5">,
                <input value="uid" id="uid" type="text" size="5">
                <input value="Start Example" id="start" type="button" onclick="startExample();">
            </p>
            <p>
                <textarea readonly id="text" cols="80" rows="24" style="resize:none;"
                          >Press "Start Example" to begin ...</textarea>
            </p>
        </div>
        <script src="./Tinkerforge.js" type='text/javascript'></script>
        <script type='text/javascript'>
            var ipcon;
            var textArea = document.getElementById("text");
            function startExample() {
                textArea.value = "";
                var HOST = document.getElementById("host").value;
                var PORT = parseInt(document.getElementById("port").value);
                var UID = document.getElementById("uid").value;
                if(ipcon !== undefined) {
                    ipcon.disconnect();
                }
                ipcon = new Tinkerforge.IPConnection(); // Create IP connection
                var he = new Tinkerforge.BrickletHallEffect(UID, ipcon); // Create device object
                ipcon.connect(HOST, PORT,
                    function(error) {
                        textArea.value += 'Error: ' + error + '\n';
                    }
                ); // Connect to brickd
                // Don't use device before ipcon is connected

                ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
                    function (connectReason) {
                        // Set period for edge count callback to 0.05s (50ms)
                        // Note: The edge count callback is only called every 0.05 seconds
                        //       if the edge count has changed since the last call!
                        he.setEdgeCountCallbackPeriod(50);
                    }
                );

                // Register edge count callback
                he.on(Tinkerforge.BrickletHallEffect.CALLBACK_EDGE_COUNT,
                    // Callback function for edge count callback
                    function (count, value) {
                        textArea.value += 'Count: ' + count + '\n';
                        textArea.scrollTop = textArea.scrollHeight;
                    }
                );
            }
        </script>
    </body>
</html>

API¶

Generally, every function of the JavaScript bindings can take two optional parameters, returnCallback and errorCallback. These are two user defined callback functions. The returnCallback function is called with the results as arguments, if the function returns its results asynchronously. The errorCallback is called with an error code in case of an error. The error code can be one of the following values:

IPConnection.ERROR_ALREADY_CONNECTED = 11
IPConnection.ERROR_NOT_CONNECTED = 12
IPConnection.ERROR_CONNECT_FAILED = 13
IPConnection.ERROR_INVALID_FUNCTION_ID = 21
IPConnection.ERROR_TIMEOUT = 31
IPConnection.ERROR_INVALID_PARAMETER = 41
IPConnection.ERROR_FUNCTION_NOT_SUPPORTED = 42
IPConnection.ERROR_UNKNOWN_ERROR = 43
IPConnection.ERROR_STREAM_OUT_OF_SYNC = 51
IPConnection.ERROR_NON_ASCII_CHAR_IN_SECRET = 71
IPConnection.ERROR_WRONG_DEVICE_TYPE = 81
IPConnection.ERROR_DEVICE_REPLACED = 82
IPConnection.ERROR_WRONG_RESPONSE_LENGTH = 83
IPConnection.ERROR_INT64_NOT_SUPPORTED = 91

The namespace for the JavaScript bindings is Tinkerforge.*.

Basic Functions¶

new BrickletHallEffect(uid, ipcon)¶

Parameters:	uid – Type: string ipcon – Type: IPConnection
Returns:	hallEffect – Type: BrickletHallEffect

Creates an object with the unique device ID uid:

var hallEffect = new BrickletHallEffect("YOUR_DEVICE_UID", ipcon);

This object can then be used after the IP Connection is connected.

BrickletHallEffect.getValue([returnCallback][, errorCallback])¶

Callback Parameters:	value – Type: boolean
Returns:	undefined

Returns true if a magnetic field of 3.5 millitesla or greater is detected.

BrickletHallEffect.getEdgeCount(resetCounter[, returnCallback][, errorCallback])¶

Parameters:	resetCounter – Type: boolean
Callback Parameters:	count – Type: int, Range: [0 to 2³² - 1]
Returns:	undefined

Returns the current value of the edge counter. You can configure edge type (rising, falling, both) that is counted with setEdgeCountConfig().

If you set the reset counter to true, the count is set back to 0 directly after it is read.

Advanced Functions¶

BrickletHallEffect.setEdgeCountConfig(edgeType, debounce[, returnCallback][, errorCallback])¶

Parameters:	edgeType – Type: int, Range: See constants, Default: 0 debounce – Type: int, Unit: 1 ms, Range: [0 to 255], Default: 100
Callback Parameters:	undefined
Returns:	undefined

The edge type parameter configures if rising edges, falling edges or both are counted. Possible edge types are:

0 = rising
1 = falling
2 = both

A magnetic field of 3.5 millitesla or greater causes a falling edge and a magnetic field of 2.5 millitesla 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).

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.

The following constants are available for this function:

For edge_type:

BrickletHallEffect.EDGE_TYPE_RISING = 0
BrickletHallEffect.EDGE_TYPE_FALLING = 1
BrickletHallEffect.EDGE_TYPE_BOTH = 2

BrickletHallEffect.getEdgeCountConfig([returnCallback][, errorCallback])¶

Callback Parameters:	edgeType – Type: int, Range: See constants, Default: 0 debounce – Type: int, Unit: 1 ms, Range: [0 to 255], Default: 100
Returns:	undefined

Returns the edge type and debounce time as set by setEdgeCountConfig().

The following constants are available for this function:

For edge_type:

BrickletHallEffect.EDGE_TYPE_RISING = 0
BrickletHallEffect.EDGE_TYPE_FALLING = 1
BrickletHallEffect.EDGE_TYPE_BOTH = 2

BrickletHallEffect.getIdentity([returnCallback][, errorCallback])¶

Callback Parameters:

Callback Parameters:	uid – Type: string, Length: up to 8 connectedUid – Type: string, Length: up to 8 position – Type: char, Range: ['a' to 'h', 'z'] hardwareVersion – Type: [int, ...], Length: 3 0: major – Type: int, Range: [0 to 255] 1: minor – Type: int, Range: [0 to 255] 2: revision – Type: int, Range: [0 to 255] firmwareVersion – Type: [int, ...], Length: 3 0: major – Type: int, Range: [0 to 255] 1: minor – Type: int, Range: [0 to 255] 2: revision – Type: int, Range: [0 to 255] deviceIdentifier – Type: int, Range: [0 to 2¹⁶ - 1]
Returns:	undefined

uid – Type: string, Length: up to 8
connectedUid – Type: string, Length: up to 8
position – Type: char, Range: ['a' to 'h', 'z']
hardwareVersion – Type: [int, ...], Length: 3

0: major – Type: int, Range: [0 to 255]
1: minor – Type: int, Range: [0 to 255]
2: revision – Type: int, Range: [0 to 255]

firmwareVersion – Type: [int, ...], Length: 3

0: major – Type: int, Range: [0 to 255]
1: minor – Type: int, Range: [0 to 255]
2: revision – Type: int, Range: [0 to 255]

deviceIdentifier – Type: int, Range: [0 to 2¹⁶ - 1]

Returns:

undefined

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). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions¶

BrickletHallEffect.on(callback_id, function[, errorCallback])¶

Parameters:	callback_id – Type: int function – Type: function
Returns:	undefined

Registers the given function with the given callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickletHallEffect.setEdgeInterrupt(edges[, returnCallback][, errorCallback])¶

Parameters:	edges – Type: int, Range: [0 to 2³² - 1], Default: 0
Callback Parameters:	undefined
Returns:	undefined

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.

BrickletHallEffect.getEdgeInterrupt([returnCallback][, errorCallback])¶

Callback Parameters:	edges – Type: int, Range: [0 to 2³² - 1], Default: 0
Returns:	undefined

Returns the edges as set by setEdgeInterrupt().

BrickletHallEffect.setEdgeCountCallbackPeriod(period[, returnCallback][, errorCallback])¶

Parameters:	period – Type: int, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0
Callback Parameters:	undefined
Returns:	undefined

Sets the period with which the CALLBACK_EDGE_COUNT callback is triggered periodically. A value of 0 turns the callback off.

The CALLBACK_EDGE_COUNT callback is only triggered if the edge count has changed since the last triggering.

BrickletHallEffect.getEdgeCountCallbackPeriod([returnCallback][, errorCallback])¶

Callback Parameters:	period – Type: int, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0
Returns:	undefined

Returns the period as set by setEdgeCountCallbackPeriod().

Callbacks¶

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the on() function of the device object. The first parameter is the callback ID and the second parameter the callback function:

hallEffect.on(BrickletHallEffect.CALLBACK_EXAMPLE,
    function (param) {
        console.log(param);
    }
);

The available constants with inherent number and type of parameters 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.

BrickletHallEffect.CALLBACK_EDGE_COUNT¶

Callback Parameters:	count – Type: int, Range: [0 to 2³² - 1] value – Type: boolean

This callback is triggered periodically with the period that is set by setEdgeCountCallbackPeriod(). The parameters are the current count and the current value (see getValue() and getEdgeCount()).

The CALLBACK_EDGE_COUNT callback is only triggered if the count or value changed since the last triggering.

Virtual Functions¶

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

BrickletHallEffect.getAPIVersion()¶

Returns:	apiVersion – Type: [int, ...], Length: 3 0: major – Type: int, Range: [0 to 255] 1: minor – Type: int, Range: [0 to 255] 2: revision – Type: int, Range: [0 to 255]

Returns the version of the API definition implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

BrickletHallEffect.getResponseExpected(functionId[, errorCallback])¶

Parameters:	functionId – Type: int, Range: See constants
Returns:	responseExpected – Type: boolean

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by setResponseExpected(). For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For function_id:

BrickletHallEffect.FUNCTION_SET_EDGE_COUNT_CONFIG = 3
BrickletHallEffect.FUNCTION_SET_EDGE_INTERRUPT = 5
BrickletHallEffect.FUNCTION_SET_EDGE_COUNT_CALLBACK_PERIOD = 7

BrickletHallEffect.setResponseExpected(functionId, responseExpected[, errorCallback])¶

Parameters:	functionId – Type: int, Range: See constants responseExpected – Type: boolean
Returns:	undefined

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled.

The following constants are available for this function:

For function_id:

BrickletHallEffect.FUNCTION_SET_EDGE_COUNT_CONFIG = 3
BrickletHallEffect.FUNCTION_SET_EDGE_INTERRUPT = 5
BrickletHallEffect.FUNCTION_SET_EDGE_COUNT_CALLBACK_PERIOD = 7

BrickletHallEffect.setResponseExpectedAll(responseExpected)¶

Parameters:	responseExpected – Type: boolean
Returns:	undefined

Changes the response expected flag for all setter and callback configuration functions of this device at once.

Constants¶

BrickletHallEffect.DEVICE_IDENTIFIER¶

This constant is used to identify a Hall Effect Bricklet.

The getIdentity() function and the IPConnection.CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BrickletHallEffect.DEVICE_DISPLAY_NAME¶: This constant represents the human readable name of a Hall Effect Bricklet.