Merge pull request #24 from tmck-code/20241210_christmas_tree_lights_…

…with_arduino

20241210 christmas tree lights with arduino

README.md

@@ -4,6 +4,10 @@ my blog
 
 ---
 
+### [20241210 Christmas Tree Lights with Arduino](articles/20241210_christmas_tree_lights_with_arduino/20241210_christmas_tree_lights_with_arduino.md)
+
+> _And a 5V WS8211 LED string 🎄_
+
 ### [20241128 Comparing Lists or Matrices](articles/20241128_comparing_lists_or_matrices/20241128_comparing_lists_or_matrices.md)
 
 > _Functional approaches to compare sequences in Python_

articles/20241210_christmas_tree_lights_with_arduino/20241210_christmas_tree_lights_with_arduino.md

@@ -0,0 +1,103 @@
+# 20241210 Christmas Tree Lights with Arduino
+
+- [20241210 Christmas Tree Lights with Arduino](#20241210-christmas-tree-lights-with-arduino)
+  - [Ingredients](#ingredients)
+    - [An Arduino board](#an-arduino-board)
+    - [A string of "WS8211" LEDs](#a-string-of-ws8211-leds)
+    - [Some patience](#some-patience)
+
+---
+
+## Ingredients
+
+### An Arduino board
+
+I used an [Arduino Uno Rev3](https://store.arduino.cc/products/arduino-uno-rev3?srsltid=AfmBOopkKaQqk6dAzd3FSnn6As2fx5D9drFTa_u-T6UkvTjJvMcMctZt)
+
+### A string of "WS8211" LEDs
+
+<img src="./ws8211_ebay_listing.png" style="width: 80%;">
+
+### Some patience
+
+Make sure you use the correct wires and ports! I struggled to find a wiring diagram on the internet, please accept this rough photo of my setup 😬:
+
+<img src="./arduino_ws8211_wiring.jpg" style="width: 50%;">
+
+### Some Code!
+
+via: https://github.com/tmck-code/ardy-pardy/blob/main/projects/xmas/xmas.ino
+
+> This uses the library `Adafruit_NeoPixel` as a dependency, which you can install via the Arduino IDE's Library Manager.
+
+```c#
+// A basic everyday NeoPixel strip test program.
+
+#include <Adafruit_NeoPixel.h>
+#ifdef __AVR__
+#endif
+
+#define LED_PIN   13
+#define LED_COUNT 50
+#define SLEEP     250
+int PIXEL_OFFSET = 0;
+
+#define WHITE  0
+#define YELLOW 1
+#define GREEN  2
+#define RED    3
+
+Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
+
+// Green, Yellow
+uint32_t COLOURS[] = {
+  strip.Color(255, 255, 255),
+  strip.Color(255, 255, 0),
+  strip.Color(0,   255, 0),
+  strip.Color(255,   0, 0)
+};
+
+int N_COLOURS = sizeof(COLOURS)/sizeof(COLOURS[0]);
+uint32_t XMAS_DUO[2] = {RED, GREEN};
+uint32_t XMAS_TRIO[3] = {RED, GREEN, YELLOW};
+
+void setup() {
+  Serial.begin(9600);
+
+  strip.begin();
+  strip.setBrightness(50);
+  strip.show();
+
+  Serial.println("Starting XMAS display with " + String(N_COLOURS) + " colours:");
+}
+
+void loop() {
+  for (int i=0; i<N_COLOURS-1; i++) {
+    colorWipe(COLOURS[i], SLEEP);
+    if (i % 2 == 0) {
+      xmas(XMAS_DUO, sizeof(XMAS_DUO)/sizeof(XMAS_DUO[0]), YELLOW);
+    } else {
+      xmas(XMAS_TRIO, sizeof(XMAS_TRIO)/sizeof(XMAS_TRIO[0]), WHITE);
+    }
+  }
+}
+
+// Fill strip pixels one after another with a color, and delay in ms.
+// Strip is NOT cleared first; anything there will be covered pixel by pixel
+void colorWipe(uint32_t color, int wait) {
+  for(int i=0; i<strip.numPixels(); i++) {
+    strip.setPixelColor(i, color);
+    strip.show();
+    delay(wait);
+  }
+}
+
+void xmas(uint32_t repeat_colours[], int n_colours, int highlight_colour) {
+  for (int i=1; i<strip.numPixels(); i++) {
+    strip.setPixelColor(i, COLOURS[highlight_colour]);
+    strip.setPixelColor(i-1, COLOURS[repeat_colours[i % n_colours]]);
+    strip.show();
+    delay(SLEEP);
+  }
+}
+```