ObjectDetector#

Initializing the ObjectDetector Class #

An Object Sensor is created by using the following constructor:

ObjectDetector(port, reverse)

This constructor uses two parameters:

Parameter	Description
`port`	The 3-Wire Port that the Object Sensor is connected to, whether it’s a port on the Brain, or a 3-Wire Expander.
`reverse`	Optional. Set this to reverse the detection logic. The default is `False`.

A Brain or 3-Wire Expander must be created first before they can be used to create an object with the ObjectDetector Class constructor.

# Create the Brain.
brain = Brain()
# Construct an ObjectSensor "objdet" with the
# ObjectDetector class.
objdet = ObjectDetector(brain.three_wire_port.a)

This objdet object will be used in all subsequent examples throughout this API documentation when referring to ObjectDetector class methods.

Class Methods #

reflectivity()#

The reflectivity(units) method returns the reflectivity measured by the Object Sensor. The reflectivity is an estimation based on the raw value of the Object Sensor.

A reflectivity of 0% is a raw value of 3000 or greater. A reflectivity of 100% is a raw value of 0.

Parameters	Description
units	Optional. The only valid unit for reflectivity is `PERCENT`.

Returns: The reflectivity measured by the Object Sensor in the range 0% - 100%.

# Print the Object Sensor's current reflectivity to the
# Brain's screen.
brain.screen.print(objdet.reflectivity())

set_threshold()#

The set_threshold(value, units) method sets the detection threshold for the Object Sensor to a specific value.

Parameters	Description
value	The reflectivity threshold for object detection. In the range 0 - 100.

Returns: None.

# Set the Object Sensor's reflectivity threhold to 50%.
objdet.set_threshold(50)

is_object_detected()#

The is_object_detected() method returns if an object is detected.

Returns: True if an object is detected. False if one is not.

changed()#

The changed(callback, arg) method registers a callback function for when the value of an Object Sensor changes.

Parameters	Description
callback	The callback function to be called when the value of an Object Sensor changes.
arg	Optional. A tuple of arguments to pass to the callback function.

Returns: An instance of the Event class.

# Define a function detector_changed().
def detector_changed():
    # The brain will print that the Object Sensor value
    # changed on the Brain's screen.
    brain.screen.print("Object Sensor value changed")

# Run detector_changed when the value of the
# Object Sensor changes.
objdet.changed(detector_changed)

object_detected()#

The object_detected(callback, arg) method registers a callback function for when an object is detected.

Parameters	Description
callback	The callback function to be called when an object is detected.
arg	Optional. A tuple of arguments to pass to the callback function.

Returns: An instance of the Event class.

# Define a function detected().
def detected():
    # The Brain will print that an object was detected
    # on the Brain's screen.
    brain.screen.print("object detected")

# Run detected when the Object Sensor detects an object.
objdet.object_detected(detected)

object_lost()#

The object_lost(callback, arg) method registers a callback function for when an object is lost.

Parameters	Description
callback	The callback function to be called when an object is lost.
arg	Optional. A tuple of arguments to pass to the callback function.

Returns: An instance of the Event class.

# Define a function lost().
def lost():
    # The Brain will print that an object was lost on the
    # Brain's screen.
    brain.screen.print("object lost")

# Run lost() when the Object Sensor loses an object.
objdet.object_lost(lost)