Here are the most common issues and solutions…
- Double-check all wiring. Are the clock and data wires swapped? Is ground connected to the Arduino?
- Confirm the Arduino is connected to the input end of the strand.
- Check power supply polarity and voltage. Are + and – swapped? If you have a multimeter, confirm 5V DC output (±10%) from the power supply.
- Are the power wires at the opposite end of the strand insulated or trimmed? They should not be left exposed where they might make contact with metal, or each other.
- Is the correct board type selected in the Arduino Tools→Board menu?
- Double-check all wiring. Are the clock and data wires swapped? Is ground connected to the Arduino?
- Confirm the Arduino is connected to the input end of the strand.
- Is the correct board type selected in the Arduino Tools→Board menu?
- Did the strandtest code successfully compile and upload?
- Confirm that the number of LEDs in the Adafruit_WS2801() constructor match the number of LEDs in the strand (both will be 25 if using the strandtest example and a single strand of LEDs).
- Inside each pixel there’s a small circuit board. Give the first bad pixel (and the one immediately before it) a firm squeeze where the ribbon cable joins the board — it may simply be a dodgy connection. If that works, you can either cut out the offending pixel and join the two sub-strands, or arrange for a replacement strand if new.
- This can happen when trying to power too long of a strand from one end. Voltage will drop along the length of the strand and the furthest pixels will “brown out.” Connect power to every 25 pixel strand.
- Confirm the library is unzipped prior to installation.
- Confirm the library is properly named and located. The folder should be called Adafruit_WS2801, and placed inside your personal Documents/Arduino/Libraries folder — not inside the Arduino application folder!
- After installation, the Arduino IDE needs to be restarted for new libraries to be used.