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160 lines
4.9 KiB
ReStructuredText
160 lines
4.9 KiB
ReStructuredText
================
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Advanced Recipes
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================
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.. currentmodule:: gpiozero
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The following recipes demonstrate some of the capabilities of the GPIO Zero
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library. Please note that all recipes are written assuming Python 3. Recipes
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*may* work under Python 2, but no guarantees!
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.. _ledboard-advanced:
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LEDBoard
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========
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You can iterate over the LEDs in a :class:`LEDBoard` object one-by-one:
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.. literalinclude:: examples/led_board_3.py
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:class:`LEDBoard` also supports indexing. This means you can access the
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individual :class:`LED` objects using ``leds[i]`` where ``i`` is an integer
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from 0 up to (not including) the number of LEDs:
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.. literalinclude:: examples/led_board_4.py
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This also means you can use slicing to access a subset of the LEDs:
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.. literalinclude:: examples/led_board_5.py
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:class:`LEDBoard` objects can have their `LED` objects named upon construction.
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This means the individual LEDs can be accessed by their name:
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.. literalinclude:: examples/led_board_6.py
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:class:`LEDBoard` objects can also be nested within other :class:`LEDBoard`
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objects:
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.. literalinclude:: examples/led_board_7.py
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Who's home indicator
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====================
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Using a number of green-red LED pairs, you can show the status of who's home,
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according to which IP addresses you can ping successfully. Note that this
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assumes each person's mobile phone has a reserved IP address on the home router.
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.. literalinclude:: examples/whos_home_leds.py
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Alternatively, using the `STATUS Zero`_ board:
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.. literalinclude:: examples/whos_home_status.py
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Travis build LED indicator
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==========================
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Use LEDs to indicate the status of a Travis build. A green light means the
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tests are passing, a red light means the build is broken:
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.. literalinclude:: examples/led_travis.py
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Note this recipe requires `travispy`_. Install with ``sudo pip3 install
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travispy``.
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Button controlled robot
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=======================
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Alternatively to the examples in the simple recipes, you can use four buttons
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to program the directions and add a fifth button to process them in turn, like
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a Bee-Bot or Turtle robot.
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.. literalinclude:: examples/robot_buttons_2.py
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Robot controlled by 2 potentiometers
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====================================
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Use two potentiometers to control the left and right motor speed of a robot:
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.. literalinclude:: examples/robot_pots_1.py
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.. note::
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Please note the example above requires Python 3. In Python 2, :func:`zip`
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doesn't support lazy evaluation so the script will simply hang.
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To include reverse direction, scale the potentiometer values from 0-1 to -1-1:
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.. literalinclude:: examples/robot_pots_2.py
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BlueDot LED
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===========
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BlueDot is a Python library an Android app which allows you to easily add
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Bluetooth control to your Raspberry Pi project. A simple example to control a
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LED using the BlueDot app:
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.. literalinclude:: examples/bluedot_led.py
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Note this recipe requires ``bluedot`` and the associated Android app. See the
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`BlueDot documentation`_ for installation instructions.
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BlueDot robot
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=============
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You can create a Bluetooth controlled robot which moves forward when the dot is
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pressed and stops when it is released:
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.. literalinclude:: examples/bluedot_robot_1.py
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Or a more advanced example including controlling the robot's speed and precise
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direction:
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.. literalinclude:: examples/bluedot_robot_2.py
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Controlling the Pi's own LEDs
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=============================
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On certain models of Pi (specifically the model A+, B+, and 2B) it's possible
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to control the power and activity LEDs. This can be useful for testing GPIO
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functionality without the need to wire up your own LEDs (also useful because
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the power and activity LEDs are "known good").
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Firstly you need to disable the usual triggers for the built-in LEDs. This can
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be done from the terminal with the following commands:
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.. code-block:: console
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$ echo none | sudo tee /sys/class/leds/led0/trigger
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$ echo gpio | sudo tee /sys/class/leds/led1/trigger
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Now you can control the LEDs with gpiozero like so:
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.. literalinclude:: examples/led_builtin.py
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To revert the LEDs to their usual purpose you can either reboot your Pi or
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run the following commands:
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.. code-block:: console
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$ echo mmc0 | sudo tee /sys/class/leds/led0/trigger
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$ echo input | sudo tee /sys/class/leds/led1/trigger
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.. note::
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On the Pi Zero you can control the activity LED with this recipe, but
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there's no separate power LED to control (it's also worth noting the
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activity LED is active low, so set ``active_high=False`` when constructing
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your LED component).
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On the original Pi 1 (model A or B), the activity LED can be controlled
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with GPIO16 (after disabling its trigger as above) but the power LED is
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hard-wired on.
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On the Pi 3B the LEDs are controlled by a GPIO expander which is not
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accessible from gpiozero (yet).
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.. _travispy: https://travispy.readthedocs.io/
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.. _STATUS Zero: https://thepihut.com/status
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.. _BlueDot documentation: https://bluedot.readthedocs.io/en/latest/index.html
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