add simple neopixel example

Author: todbot

README.md

@@ -36,6 +36,7 @@ But it's probably easiest to do a Cmd-F/Ctrl-F find on keyword of idea you want.
    * [Control Neopixel / WS2812 LEDs](#control-neopixel--ws2812-leds)
    * [Control a servo, with animation list](#control-a-servo-with-animation-list)
 * [Neopixels / Dotstars](#neopixels--dotstars)
+   * [Light each LED in order](#light-each-led-in-order)
    * [Moving rainbow on built-in board.NEOPIXEL](#moving-rainbow-on-built-in-boardneopixel)
    * [Make moving rainbow gradient across LED strip](#make-moving-rainbow-gradient-across-led-strip)
    * [Fade all LEDs by amount for chase effects](#fade-all-leds-by-amount-for-chase-effects)
@@ -380,6 +381,30 @@ while True:
 
 ## Neopixels / Dotstars
 
+### Light each LED in order
+
+You can access each LED with Python array methods on the `leds` object.
+And you can set the LED color with either an RGB tuple (`(255,0,80)`) or an
+RGB hex color as a 24-bit number (`0xff0050`)
+
+```py
+import time, board, neopixel
+
+led_pin = board.GP5   # which pin the LED strip is on
+num_leds = 10
+colors = ( (255,0,0), (0,255,0), (0,0,255), 0xffffff, 0x000000 )
+
+leds = neopixel.NeoPixel(led_pin, num_leds, brightness=0.1)
+
+i = 0
+while True:
+    print("led:",i)
+    for c in colors:
+        leds[i] = c
+        time.sleep(0.2)
+    i = (i+1) % num_leds
+```
+
 ### Moving rainbow on built-in `board.NEOPIXEL`
 
 In CircuitPython 7, the `rainbowio` module has a `colorwheel()` function.

larger-tricks/bouncy_balls_vectorio.py

@@ -1,6 +1,7 @@
 # bouncy_balls_vectorio.py - use displayio to make simple bouncy balls
 # 12 Nov 2024 - @todbot / Tod Kurt.  Based off bouncy_balls1.py
 # video demo at https://gist.github.com/todbot/d216cdfd0c13774c713482395429da16
+# works on any CircuitPython device with a display, just create a 'display'
 import time, random
 import board, busio, displayio, i2cdisplaybus
 import vectorio
@@ -13,7 +14,7 @@
 scl_pin, sda_pin = board.GP15, board.GP14    # pins your display is on
 dw,dh = 128,64  # or whatever your display is
 
-# set up the display
+# set up the display (change for your setup)
 displayio.release_displays()
 disp_i2c = busio.I2C(scl=scl_pin, sda=sda_pin, frequency=400_000)
 display_bus = i2cdisplaybus.I2CDisplayBus(disp_i2c, device_address=0x3C)  # or 0x3D