Error running neopixel_demo.py

[MarkEstrada]

I am trying to run the neopixel_demo.py but I am encountering this problem

pi@raspberrypi:~/playground/neopixel $ python3 neopixel_demo.py
Traceback (most recent call last):
  File "neopixel_demo.py", line 19, in <module>
    device = neopixel(width=8, height=4)
  File "/home/pi/.local/lib/python3.7/site-packages/luma/led_matrix/device.py", line 223, in __init__
    ws = self._ws = dma_interface or self.__ws281x__()
  File "/home/pi/.local/lib/python3.7/site-packages/luma/led_matrix/device.py", line 264, in __ws281x__
    import _rpi_ws281x
ModuleNotFoundError: No module named '_rpi_ws281x'
Exception ignored in: <function ws2812.__del__ at 0xb5e075d0>
Traceback (most recent call last):
  File "/home/pi/.local/lib/python3.7/site-packages/luma/led_matrix/device.py", line 322, in __del__
    if self._ws is not None:
AttributeError: 'ws2812' object has no attribute '_ws'

Not sure but I followed everything in Installation section

I have validated my luma library as the following

pi@raspberrypi:~/playground/neopixel $ pip3 freeze | grep luma
luma.core==1.15.0
luma.led-matrix==1.5.0

I have raspberry pi zero w running on headless setup

pi@raspberrypi:~/playground/neopixel $ cat /etc/os-release
PRETTY_NAME="Raspbian GNU/Linux 10 (buster)"
NAME="Raspbian GNU/Linux"
VERSION_ID="10"
VERSION="10 (buster)"
VERSION_CODENAME=buster
ID=raspbian
ID_LIKE=debian
HOME_URL="http://www.raspbian.org/"
SUPPORT_URL="http://www.raspbian.org/RaspbianForums"
BUG_REPORT_URL="http://www.raspbian.org/RaspbianBugs"
pi@raspberrypi:~/playground/neopixel $ cat /etc/debian_version
10.4
pi@raspberrypi:~/playground/neopixel $ uname -a
Linux raspberrypi 5.4.51+ #1327 Thu Jul 23 10:53:06 BST 2020 armv6l GNU/Linux

Any hints?

_Originally posted by @MarkEstrada in https://github.com/rm-hull/luma.led_matrix/issues/228#issuecomment-674004327_

[rm-hull]

I think that the ws2812 and rpi_ws281x modules only gets installed on certain linux platforms: https://github.com/rm-hull/luma.led_matrix/blob/master/setup.py#L68-L71 shows:

extras_require={
        ':platform_machine=="armv7l" and platform_system=="Linux"': [
            'ws2812', 'rpi_ws281x'
        ],

And looking at the output of uname -a shows arm6l. I dont recall exactly why we target arm7l specifically ... @thijstriemstra do you remember? I cant see any issue with extending this for arm6l

[MarkEstrada]

Additional comment also maybe this could help in debugging... I have tried the matrix_demo.py and this works perfectly. I am able to control everything using this awesome library of yours.

So I am quite sure that I followed the installation section as described. Not sure what the problem is at the neopixel demo. Thanks!

[Gadgetoid]

Can confirm that all Pi Zero platforms support rpi_ws281x, and can't think of any good reason to limit to armv7l.

[rm-hull]

@MarkEstrada the python setup script will only install the low level drivers for neopixels if the platform is arm7l, and your RPi Zero is showing the platform as arm6l, so it is not installing some critical components. I will get this fixed, but in the short term, you could just run the following:

sudo pip3 install ws2812 rpi_ws281x

Then try the demo script again - hopefully it should work.

[MarkEstrada]

@MarkEstrada the python setup script will only install the low level drivers for neopixels if the platform is arm7l, and your RPi Zero is showing the platform as arm6l, so it is not installing some critical components. I will get this fixed, but in the short term, you could just run the following:

sudo pip3 install ws2812 rpi_ws281x

Then try the demo script again - hopefully it should work.

I did tried this but I am running into a different issue

pi@raspberrypi:~/playground/neopixel $ python3 neopixel_demo.py
Can't open /dev/mem: Permission denied
Traceback (most recent call last):
  File "neopixel_demo.py", line 19, in <module>
    device = neopixel(width=8, height=8)
  File "/home/pi/.local/lib/python3.7/site-packages/luma/led_matrix/device.py", line 258, in __init__
    raise RuntimeError('ws2811_init failed with code {0}'.format(resp))
RuntimeError: ws2811_init failed with code -5
Segmentation fault
pi@raspberrypi:~/playground/neopixel $ sudo python3 neopixel_demo.py
Traceback (most recent call last):
  File "neopixel_demo.py", line 13, in <module>
    from luma.led_matrix.device import neopixel
ModuleNotFoundError: No module named 'luma'

I have not been running my python scripts as sudo I think..Not sure if this is mandatory when using this library or I might be missing something? I just started exploring Rpi development.

[thijstriemstra]

I dont recall exactly why we target arm7l specifically ... @thijstriemstra do you remember?

Not really.

Can confirm that all Pi Zero platforms support rpi_ws281x, and can't think of any good reason to limit to armv7l.

Agreed. Pull request welcome.

[MarkEstrada]

Got it to work! Thanks for the help. Awesome job guys!

[rm-hull]

@MarkEstrada for the benefit of others who might be in the same situation ... what did you do to get it working?

[MarkEstrada]

@MarkEstrada for the benefit of others who might be in the same situation ... what did you do to get it working?

Oh my bad...sorry for not explaining what I did.

I followed your suggestion to install this sudo pip3 install ws2812 rpi_ws281x

and run everything in sudo mode. That did the trick!

Thank you for coming up with this awesome library!