NeoPixels Strip on Raspberry Pi Zero

Looking into my desk’s drawer I found the remainder of an Adafruit NeoPixel strip I used in another project. And an unused, last years Raspberry Pi Zero. Does that work together? Well, yes, it does! At least after fiddling a bit with hard- and software and circumventing some common traps.

Searching the web I found a tutorial for steering a NeoPixel strip with a first generation Raspberry Pi. Technically it should work with an exemplary of a more recent version, but it did not initially.
Here is the description of how it all worked out in the end:

Hardware

Raspberry Pi Zero with up-to-date Raspbian Jessie Pixel
Mini USB WiFi Adapter (if the brand new Raspberry Pi Zero W is not used)
Raspberry Pi Zero adapter cables + power supply
Adafruit NeoPixel strip
1000 μF capacitor
330 Ω resistor
1N4001 diode
5 V breadboard power supply
breadbord, cables

Connections

  • 5V power supply GND : 1000 μF capacitor (short leg)
  • 5V power supply 5V : 1000 μF capacitor
  • 5V power supply GND : NeoPixel strip GND
  • 5V power supply 5V : NeoPixel strip 5V via 1N4001 diode (side with stripe goes to 5V input of the strip)
  • 5V power supply GND : Raspberry Pi Zero GND (physical pin 6)
  • Raspberry Pi Zero (physical pin 12) : NeoPixel strip data line via 330 Ω resistor

The available pins of the Raspberry Pi Zero are listed here. GPIO #1 correlates to physical pin 12 which is BCM #18. The latter is used in the Python software.

Don’t!

It is not recommended to use the 5V output of the Raspberry Pi Zero directly to power the NeoPixel strip. The pixels might draw too much current and might therefore damage the pin. It would have been way too convenient…so: an additional 5V power supply is strongly recommended.

Software

Running Headless: Setting up WiFi

To run the Raspberry Pi Zero headless (without display), set up the WiFi connection. For this step an HDMI display and a keyboard is required. Open the file

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

Put the network configuration at the end of the file:

network={
ssid="WiFi network name"
psk="password"
}

Use raspi-config to allow SSH connections and to adjust the Pi’s hostname, the password, the time settings etc. .

SSH to Zero

When attaching the Mini USB WiFi Adapter instead of the keyboard and rebooting the Raspberry Pi Zero the desired WiFi network is used and it is possible to SSH to the Pi Zero. To find the IP adress in the local network check which devices are logged into the network at your routers access point. Or kindly ask your network admin to check. 😉

GPIO Checks

To see the available GPIO pins on the Raspberry Pi Zero run

gpio readall

NeoPixel Python Library

To set up the Python library for driving NeoPixels on a Raspberry follow this tutorial. Jeremy Garff’s Python library for NeoPixels is working like a charm.

Disabling Audio

To be able to use the PWM pins as data pins for the NeoPixel strip I disabled audio by commenting the line

# Enable audio (loads snd_bcm2835)
#dtparam=audio=on  # disable audio for PWM pin usage

in the file /boot/config.txt.

Whether audio is disabled can be checked using

aplay -l

. If audio is disabled properly the result is an error message („aplay: device_list:268: no soundcards found…“).

Examples

Once the NeoPixel library is set up and the hardware is connected properly run strandtest.py or any other example code from the rpi_ws281x/python/examples section.

Result

That’s it! The NeoPixel strip finally can be driven by a Raspberry Pi Zero.

neopixeltest

While this example is working I definitively have a new project in mind…

Links

https://learn.adafruit.com/neopixels-on-raspberry-pi/overview

https://github.com/jgarff/rpi_ws281x

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