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# Perl - Distance IR Bricklet

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

## Examples

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

### Simple

Download (example_simple.pl)

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    #!/usr/bin/perl

    use Tinkerforge::IPConnection;
    use Tinkerforge::BrickletDistanceIR;

    use constant HOST => 'localhost';
    use constant PORT => 4223;
    use constant UID => 'hJY'; # Change to your UID

    my $ipcon = Tinkerforge::IPConnection->new(); # Create IP connection
    my $dist = Tinkerforge::BrickletDistanceIR->new(&UID, $ipcon); # Create device object

    $ipcon->connect(&HOST, &PORT); # Connect to brickd
    # Don't use device before ipcon is connected

    # Get current distance (unit is mm)
    my $distance = $dist->get_distance()/10.0;

    print "Distance: $distance cm\n";

    print "Press any key to exit...\n";
    <STDIN>;
    $ipcon->disconnect();

### Callback

Download (example_callback.pl)

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    #!/usr/bin/perl

    use Tinkerforge::IPConnection;
    use Tinkerforge::BrickletDistanceIR;

    use constant HOST => 'localhost';
    use constant PORT => 4223;
    use constant UID => 'hJY'; # Change to your UID

    my $ipcon = Tinkerforge::IPConnection->new(); # Create IP connection
    my $dist = Tinkerforge::BrickletDistanceIR->new(&UID, $ipcon); # Create device object

    # Callback function for distance callback (parameter has unit mm)
    sub cb_distance
    {
        my ($distance) = @_;

        print "Distance: ".$distance/10.0." cm\n";
    }

    $ipcon->connect(&HOST, &PORT); # Connect to brickd
    # Don't use device before ipcon is connected

    # Set Period for distance callback to 0.2s (200ms)
    # Note: The callback is only called every 200ms if the
    #       distance has changed since the last call!
    $dist->set_distance_callback_period(200);

    # Register distance callback to function cb_distance
    $dist->register_callback($dist->CALLBACK_DISTANCE, 'cb_distance');

    print "Press any key to exit...\n";
    <STDIN>;
    $ipcon->disconnect();

### Threshold

Download (example_threshold.pl)

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    #!/usr/bin/perl

    use Tinkerforge::IPConnection;
    use Tinkerforge::BrickletDistanceIR;

    use constant HOST => 'localhost';
    use constant PORT => 4223;
    use constant UID => 'hJY'; # Change to your UID

    my $ipcon = Tinkerforge::IPConnection->new(); # Create IP connection
    my $dist = Tinkerforge::BrickletDistanceIR->new(&UID, $ipcon); # Create device object

    # Callback function for distance callback (parameter has unit mm)
    sub cb_reached
    {
        my ($distance) = @_;

        print "Distance is smaller than 20cm: ".$distance/10.0." cm\n";
    }

    $ipcon->connect(&HOST, &PORT); # Connect to brickd
    # Don't use device before ipcon is connected

    # Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    $dist->set_debounce_period(10000);

    # Register threshold reached callback to function cb_reached
    $dist->register_callback($dist->CALLBACK_DISTANCE_REACHED, 'cb_reached');

    # Configure threshold for "smaller than 20cm" (unit is mm)
    $dist->set_distance_callback_threshold('<', 200, 0);

    print "Press any key to exit...\n";
    <STDIN>;
    $ipcon->disconnect();

## API

Generally, every subroutine of the Perl bindings can report an error as `Tinkerforge::Error` object via `croak()`. The object has a `get_code()` and a `get_message()` subroutine. There are different error code:

- Error->ALREADY_CONNECTED = 11
- Error->NOT_CONNECTED = 12
- Error->CONNECT_FAILED = 13
- Error->INVALID_FUNCTION_ID = 21
- Error->TIMEOUT = 31
- Error->INVALID_PARAMETER = 41
- Error->FUNCTION_NOT_SUPPORTED = 42
- Error->UNKNOWN_ERROR = 43

All methods listed below are thread-safe.

### Basic Functions

`BrickletDistanceIR``->``new`($uid, $ipcon)

  Parameters:

  - $uid -- string
  - $ipcon -- IPConnection

  Return type: | BrickletDistanceIR

  Creates an object with the unique device ID `$uid`:

      $distance_ir = BrickletDistanceIR->new("YOUR_DEVICE_UID", $ipcon);

  This object can then be used after the IP Connection is connected (see examples above).

`BrickletDistanceIR``->``get_distance`()

  Return type: | int

  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 `CALLBACK_DISTANCE` and set the period with `set_distance_callback_period()`.

### Advanced Functions

`BrickletDistanceIR``->``get_analog_value`()

  Return type: | int

  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 `CALLBACK_ANALOG_VALUE` and set the period with `set_analog_value_callback_period()`.

`BrickletDistanceIR``->``set_sampling_point`($position, $distance)

  Parameters:

  - $position -- int
  - $distance -- int

  Return type: | undef

  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.

`BrickletDistanceIR``->``get_sampling_point`($position)

  Parameters: | $position -- int
  Return type: | int

  Returns the distance to a sampling point position as set by `set_sampling_point()`.

`BrickletDistanceIR``->``get_api_version`()

  Return type: | [int, int, int]

  Returns the version of the API definition (major, minor, revision) 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.

`BrickletDistanceIR``->``get_response_expected`($function_id)

  Parameters: | $function_id -- int
  Return type: | bool

  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 `set_response_expected()`. 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 send and errors are silently ignored, because they cannot be detected.

  See `set_response_expected()` for the list of function ID constants available for this function.

`BrickletDistanceIR``->``set_response_expected`($function_id, $response_expected)

  Parameters:

  - $function_id -- int
  - $response_expected -- bool

  Return type: | undef

  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 and callbacks it is always disabled.

  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 send and errors are silently ignored, because they cannot be detected.

  The following function ID constants are available for this function:

  - BrickletDistanceIR->FUNCTION_SET_SAMPLING_POINT = 3
  - BrickletDistanceIR->FUNCTION_SET_DISTANCE_CALLBACK_PERIOD = 5
  - BrickletDistanceIR->FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 7
  - BrickletDistanceIR->FUNCTION_SET_DISTANCE_CALLBACK_THRESHOLD = 9
  - BrickletDistanceIR->FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 11
  - BrickletDistanceIR->FUNCTION_SET_DEBOUNCE_PERIOD = 13

`BrickletDistanceIR``->``set_response_expected_all`($response_expected)

  Parameters: | $response_expected -- bool
  Return type: | undef

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

`BrickletDistanceIR``->``get_identity`()

  Return type: | [string, string, char, [int, int, int], [int, int, int], int]

  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. There is also a constant for the device identifier of this Bricklet.

  The returned array contains the elements `uid`, `connected_uid`, `position`, `hardware_version`, `firmware_version` and `device_identifier`.

### Callback Configuration Functions

`BrickletDistanceIR``->``register_callback`($id, $callback)

  Parameters:

  - $id -- int
  - $callback -- string

  Return type: | undef

  Registers a callback with ID `$id` to the function named `$callback`. The available IDs with corresponding function signatures are listed below.

`BrickletDistanceIR``->``set_distance_callback_period`($period)

  Parameters: | $period -- int
  Return type: | undef

  Sets the period in ms with which the `CALLBACK_DISTANCE` callback is triggered periodically. A value of 0 turns the callback off.

  `CALLBACK_DISTANCE` is only triggered if the distance has changed since the last triggering.

  The default value is 0.

`BrickletDistanceIR``->``get_distance_callback_period`()

  Return type: | int

  Returns the period as set by `set_distance_callback_period()`.

`BrickletDistanceIR``->``set_analog_value_callback_period`($period)

  Parameters: | $period -- int
  Return type: | undef

  Sets the period in ms with which the `CALLBACK_ANALOG_VALUE` callback is triggered periodically. A value of 0 turns the callback off.

  `CALLBACK_ANALOG_VALUE` is only triggered if the analog value has changed since the last triggering.

  The default value is 0.

`BrickletDistanceIR``->``get_analog_value_callback_period`()

  Return type: | int

  Returns the period as set by `set_analog_value_callback_period()`.

`BrickletDistanceIR``->``set_distance_callback_threshold`($option, $min, $max)

  Parameters:

  - $option -- char
  - $min -- int
  - $max -- int

  Return type: | undef

  Sets the thresholds for the `CALLBACK_DISTANCE_REACHED` callback.

  The following options are possible:

  Option | Description
  --- | ---
  '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 constants are available for this function:

  - BrickletDistanceIR->THRESHOLD_OPTION_OFF = 'x'
  - BrickletDistanceIR->THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletDistanceIR->THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletDistanceIR->THRESHOLD_OPTION_SMALLER = '<'
  - BrickletDistanceIR->THRESHOLD_OPTION_GREATER = '>'

`BrickletDistanceIR``->``get_distance_callback_threshold`()

  Return type: | [char, int, int]

  Returns the threshold as set by `set_distance_callback_threshold()`.

  The following constants are available for this function:

  - BrickletDistanceIR->THRESHOLD_OPTION_OFF = 'x'
  - BrickletDistanceIR->THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletDistanceIR->THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletDistanceIR->THRESHOLD_OPTION_SMALLER = '<'
  - BrickletDistanceIR->THRESHOLD_OPTION_GREATER = '>'

  The returned array contains the elements `option`, `min` and `max`.

`BrickletDistanceIR``->``set_analog_value_callback_threshold`($option, $min, $max)

  Parameters:

  - $option -- char
  - $min -- int
  - $max -- int

  Return type: | undef

  Sets the thresholds for the `CALLBACK_ANALOG_VALUE_REACHED` callback.

  The following options are possible:

  Option | Description
  --- | ---
  '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 constants are available for this function:

  - BrickletDistanceIR->THRESHOLD_OPTION_OFF = 'x'
  - BrickletDistanceIR->THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletDistanceIR->THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletDistanceIR->THRESHOLD_OPTION_SMALLER = '<'
  - BrickletDistanceIR->THRESHOLD_OPTION_GREATER = '>'

`BrickletDistanceIR``->``get_analog_value_callback_threshold`()

  Return type: | [char, int, int]

  Returns the threshold as set by `set_analog_value_callback_threshold()`.

  The following constants are available for this function:

  - BrickletDistanceIR->THRESHOLD_OPTION_OFF = 'x'
  - BrickletDistanceIR->THRESHOLD_OPTION_OUTSIDE = 'o'
  - BrickletDistanceIR->THRESHOLD_OPTION_INSIDE = 'i'
  - BrickletDistanceIR->THRESHOLD_OPTION_SMALLER = '<'
  - BrickletDistanceIR->THRESHOLD_OPTION_GREATER = '>'

  The returned array contains the elements `option`, `min` and `max`.

`BrickletDistanceIR``->``set_debounce_period`($debounce)

  Parameters: | $debounce -- int
  Return type: | undef

  Sets the period in ms with which the threshold callbacks

  - `CALLBACK_DISTANCE_REACHED`,
  - `CALLBACK_ANALOG_VALUE_REACHED`

  are triggered, if the thresholds

  - `set_distance_callback_threshold()`,
  - `set_analog_value_callback_threshold()`

  keep being reached.

  The default value is 100.

`BrickletDistanceIR``->``get_debounce_period`()

  Return type: | int

  Returns the debounce period as set by `set_debounce_period()`.

### Callbacks

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

    sub my_callback
    {
        print "@_[0]";
    }

    $distance_ir->register_callback(BrickletDistanceIR->CALLBACK_EXAMPLE, 'my_callback')

The callback function will be called from an internal thread of the IP Connection. In contrast to many other programming languages, variables are not automatically shared between threads in Perl. If you want to share a global variable between a callback function and the rest for your program it has to be marked as `:shared`. See the documentation of the threads::shared Perl module for more details.

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.

`BrickletDistanceIR``->``CALLBACK_DISTANCE`

  Parameters: | $distance -- int

  This callback is triggered periodically with the period that is set by `set_distance_callback_period()`. The parameter is the distance of the sensor.

  `CALLBACK_DISTANCE` is only triggered if the distance has changed since the last triggering.

`BrickletDistanceIR``->``CALLBACK_ANALOG_VALUE`

  Parameters: | $value -- int

  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.

  `CALLBACK_ANALOG_VALUE` is only triggered if the analog value has changed since the last triggering.

`BrickletDistanceIR``->``CALLBACK_DISTANCE_REACHED`

  Parameters: | $distance -- int

  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()`.

`BrickletDistanceIR``->``CALLBACK_ANALOG_VALUE_REACHED`

  Parameters: | $value -- int

  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()`.

### Constants

`BrickletDistanceIR``->``DEVICE_IDENTIFIER`

  This constant is used to identify a Distance IR Bricklet.

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

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