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 strip. If your strip came with a plug pre-soldered, there is only a 50/50 chance this is the correct end. Examine the strip closely, and solder wires to the INPUT end if needed.
- Check power supply polarity and voltage. Are + and - swapped? If you have a multimeter, confirm 5V DC output (±10%) from the power supply.
- 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 strip. If your strip came with a plug pre-soldered, there is only a 50/50 chance this is the correct end. Examine the strip closely, and solder wires to the INPUT end if needed.
- 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 LPD8806() constructor match the number of LEDs in the strip (both will be 32 if using the strandtest example and a single meter of LEDs).
- Check for conductive detritus that may have gotten into the strip: solder balls, frayed bits of wire, etc.
- Between each pair of LEDs there’s a small chip. Find the chip corresponding to the first bad LED, and give the strip a firm squeeze here — it may simply be a dodgy connection. Try this with the prior chip as well. If that works, you can either touch up the connections with a soldering iron, cut out the offending section of strip and join the two sub-strips, or arrange for a replacement strip if it’s new.
- This can happen when trying to power too long of a strip from one end. Voltage will drop along the length of the strip and the furthest pixels will “brown out.” Connect power every meter.
- Confirm the library is unzipped prior to installation.
- Confirm the library is properly named and located. The folder should be called LPD8806, 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.