Hello, Pixels: Your First Test Sketch

Before the board hosts a web page, prove the lights work on their own. A moving rainbow lights every pixel, so it shows wiring problems fast.

Step 1: Set up the Arduino IDE#

1. Open Boards Manager and install the package for your board: esp8266 or esp32.
2. Open Library Manager, search for Adafruit NeoPixel, and install it.
3. Select your board and port under the Tools menu.

• Board package installed
• Adafruit NeoPixel library installed
• Board and port selected

Step 2: Upload the sketch#

Copy the sketch below into a new window, set the pin number for your board, and upload it. The sketch keeps the brightness low on purpose, so a first test cannot overload the supply.

#include <Adafruit_NeoPixel.h>

#define LED_PIN    D4     // NodeMCU and Wemos labels. On an ESP32, use a GPIO number such as 5.
#define LED_COUNT  200
#define BRIGHTNESS 60     // 0 to 255. Raise it only after the power wiring is proven.

Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  strip.begin();
  strip.setBrightness(BRIGHTNESS);
  strip.show();           // start with every pixel off
}

void loop() {
  for (uint16_t offset = 0; offset < 65536UL; offset += 256) {
    for (int i = 0; i < LED_COUNT; i++) {
      uint16_t hue = offset + (uint32_t)i * 65536UL / LED_COUNT;
      strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(hue)));
    }
    strip.show();
    delay(10);
  }
}

• Pin number matches the pin you wired in Part 1
• Sketch uploads without errors
• A rainbow moves along the whole string

Troubleshooting#

Only the first few pixels light. The data signal is being lost after those pixels. Check the data connection between the last working pixel and the next one.

Colors are wrong, such as red where green should be. Your pixels use a different color order. Change NEO_GRB to NEO_RGB and upload again.

The board resets when the lights start. The pixels are pulling power from the wrong place. Go back to Part 1 and check that the pixels run from the supply, not the board.

What is next#

The next part puts a web page on the board. See the full series for the plan.