arduino_io example of toggling GPIO

arduino_io.ipynb

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    "# Example overlay showing how to toggle Arduino pins \n",
    "\n",
    "This example uses the PYNQ-Z2 with the `base` overlay, and the `Arduino_IO` class.\n",
    "\n",
    "## Import BaseOverlay and Arduino_IO"
   ]
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   "cell_type": "code",
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   "source": [
    "from pynq.overlays.base import BaseOverlay\n",
    "from pynq.lib.arduino import Arduino_IO\n",
    "\n",
    "base = BaseOverlay(\"base.bit\")"
   ]
  },
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   "cell_type": "markdown",
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   "source": [
    "## Get handles to Arduino pins\n",
    "\n",
    "The Arduino pins are connected to a MicroBlaze microprocessor in the base overlay. `base.ARDUINO` is a handle for this processor and needs to be passed as a parameter to the Arduino_IO class. \n",
    "Pins D0-D19 on the Ardunio interface can be selected by index (0-19), and the direction of the pin input or output is specified with 'in' or 'out'. "
   ]
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    "arduino_pin_d0 = Arduino_IO(base.ARDUINO, 0, 'out')\n",
    "arduino_pin_d1 = Arduino_IO(base.ARDUINO, 1, 'in')"
   ]
  },
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   "source": [
    "We can now call `.read()` or `.write()` for each pin"
   ]
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    "arduino_pin_d0.write(1)"
   ]
  },
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   "cell_type": "code",
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   "metadata": {},
   "outputs": [],
   "source": [
    "arduino_pin_d1.read()"
   ]
  },
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   "source": [
    "# Add a toggle button widget "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "import ipywidgets as widgets\n",
    "from IPython.display import display"
   ]
  },
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   "source": [
    "Add button widget, and define function to turn pin \"on\"/\"off\" when button is clicked."
   ]
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   "source": [
    "# Start \"off\":\n",
    "arduino_pin_d0.write(0)      \n",
    "\n",
    "# Create the toggle button\n",
    "toggleButton = widgets.ToggleButtons(\n",
    "    options=['off', 'on']\n",
    ")\n",
    "\n",
    "# create function to be called on button change\n",
    "def toggle_pin(button_value):\n",
    "    if(button_value.new is \"off\"):\n",
    "        arduino_pin_d0.write(0)\n",
    "    else:\n",
    "        arduino_pin_d0.write(1)\n",
    "\n",
    " \n",
    "# Observe the button and call the toggle_pin function when it is clicked. \n",
    "# Pass the *value* of the button to the function (this will be \"on\" or \"off\")\n",
    "toggleButton.observe(toggle_pin,'value')\n",
    "\n",
    "# Display the button\n",
    "display(toggleButton)"
   ]
  },
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