feat: Add NeoPixel demo

demos/neopixel/neopixel.ino

@@ -0,0 +1,35 @@
+
+#include <Adafruit_NeoPixel.h>   // version 1.15.2
+
+
+#define PIN        18
+#define NUMPIXELS 1
+ 
+// When setting up the NeoPixel library, we tell it how many pixels,
+// and which pin to use to send signals. Note that for older NeoPixel
+// strips you might need to change the third parameter -- see the
+// strandtest example for more information on possible values.
+Adafruit_NeoPixel pixels(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);
+
+#define DELAYVAL 500 // Time (in milliseconds) to pause between pixels
+
+void setup() {
+  pixels.begin(); // INITIALIZE NeoPixel strip object (REQUIRED)
+}
+
+void loop() {
+  pixels.clear(); // Set all pixel colors to 'off'
+
+  // The first NeoPixel in a strand is #0, second is 1, all the way up
+  // to the count of pixels minus one.
+  for(int i=0; i<NUMPIXELS; i++) { // For each pixel...
+
+    // pixels.Color() takes RGB values, from 0,0,0 up to 255,255,255
+    // Here we're using a moderately bright green color:
+    pixels.setPixelColor(i, pixels.Color(0, 150, 0));
+
+    pixels.show();   // Send the updated pixel colors to the hardware.
+
+    delay(DELAYVAL); // Pause before next pass through loop
+  }
+}