Add asyncio template code.

Author: kattni

CircuitPython_Templates/asyncio/code.py

@@ -0,0 +1,84 @@
+# SPDX-FileCopyrightText: Copyright (c) 2022 Dan Halbert for Adafruit Industries
+# SPDX-FileCopyrightText: Copyright (c) 2022 Kattni Rembor for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+"""
+CircuitPython asyncio example for two NeoPixel rings and one button.
+REMOVE THIS LINE AND THE REST OF THIS DOCSTRING BEFORE SUBMITTING TO LEARN
+
+Update BUTTON to the pin that matches the pin to which the button is connected.
+
+For example, on the QT Py RP2040, you would leave it as BUTTON to use the built-in Boot button.
+On the Feather M4 Express, you would wire the external button to A0, and update BUTTON to A0.
+"""
+import asyncio
+import board
+import neopixel
+import keypad
+from rainbowio import colorwheel
+
+button_pin = board.BUTTON  # The pin the button is connected to.
+num_pixels = 16  # The number of NeoPixels on a single ring.
+brightness = 0.2  # The LED brightness.
+
+# Set up NeoPixel rings.
+ring_one = neopixel.NeoPixel(board.A1, num_pixels, brightness=brightness, auto_write=False)
+ring_two = neopixel.NeoPixel(board.A2, num_pixels, brightness=brightness, auto_write=False)
+
+
+class AnimationControls:
+    """The controls to allow you to vary the rainbow and blink animations."""
+    def __init__(self):
+        self.reverse = False
+        self.wait = 0.0
+        self.delay = 0.5
+
+
+async def rainbow_cycle(animation_controls):
+    """Rainbow cycle animation on ring one."""
+    while True:
+        for j in range(255, -1, -1) if animation_controls.reverse else range(0, 256, 1):
+            for i in range(num_pixels):
+                rc_index = (i * 256 // num_pixels) + j
+                ring_one[i] = colorwheel(rc_index & 255)
+            ring_one.show()
+            await asyncio.sleep(animation_controls.wait)
+
+
+async def blink(animation_controls):
+    """Blink animation on ring two."""
+    while True:
+        ring_two[:] = [(0, 0, abs(ring_two[0][2] - 255))] * num_pixels
+        await asyncio.sleep(animation_controls.delay)
+        ring_two.show()
+        await asyncio.sleep(animation_controls.wait)
+
+
+async def monitor_button(button, animation_controls):
+    """Monitor button that reverses rainbow direction and changes blink speed.
+    Assume button is active low.
+    """
+    with keypad.Keys((button,), value_when_pressed=False, pull=True) as key:
+        while True:
+            key_event = key.events.get()
+            if key_event:
+                if key_event.pressed:
+                    animation_controls.reverse = True
+                    animation_controls.delay = 0.1
+                elif key_event.released:
+                    animation_controls.reverse = False
+                    animation_controls.delay = 0.5
+            # Let another task run.
+            await asyncio.sleep(0)
+
+
+async def main():
+    animation_controls = AnimationControls()
+    buttons_task = asyncio.create_task(monitor_button(button_pin, animation_controls))
+    animation_task = asyncio.create_task(rainbow_cycle(animation_controls))
+    blink_task = asyncio.create_task(blink(animation_controls))
+
+    # This will run forever, because no tasks ever finish.
+    await asyncio.gather(buttons_task, animation_task, blink_task)
+
+asyncio.run(main())