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70 lines
2.3 KiB
ReStructuredText
70 lines
2.3 KiB
ReStructuredText
==================
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Recipes (Advanced)
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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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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, use four buttons to program the directions and add a fifth
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button to process them in turn, like a Bee-Bot or Turtle robot.
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.. literalinclude:: examples/robot_buttons_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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$ 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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$ 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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