Direct NeoPixel don't work with DMA 5 on Rasp 3B

[hprotzek]

The default setting in neopixel_direct.py with DMA 5 doesn't work on Raspberry Pi 3. Test with the strandtest.py (default DMA 10) of the rpi_ws281x library were successful.

Also there seem to be an issue with DMA 5: jgarff/rpi_ws281x#224

Can you make the DMA channel configurable? or change the default to 10?

[gordonturner]

To provide another data point, had the same issue, edited neopixel_direct.py to switch the DMA from 5 to 10:

vi ./oprint/lib/python2.7/site-packages/octoprint_enclosure/neopixel_direct.py

LED_INVERT = False
# CHANGED
#LED_DMA = 5
LED_DMA = 10
LED_FREQ_HZ = 800000

Also on a Raspberry Pi 3.

Edit:

For me, in order to use sudo without entering the password I had to edit the sudoers:

sudo visudo

# ADDED TO END
pi ALL=(ALL) NOPASSWD: ALL

Maybe something for the docs?

[vitormhenrique]

@gordonturner You might get away removing sudo from from the advanced sections of the plugin and giving pi user access to gpio, but I don't know...

@hprotzek For now as a work around manually update the DMA from 5 to 10. I'll make it configurable on a patch.

[gordonturner]

@vitormhenrique tried a couple of time to set the permissions (please see below) but none of them seemed to work. I would of course prefer not to use sudo if possible :-)

If there is something I am missing, please let me know.

Attempt 1

• Remove sudo requirement

• Reference:

https://raspberrypi.stackexchange.com/questions/40105/access-gpio-pins-without-root-no-access-to-dev-mem-try-running-as-root

• Check that /dev/gpiomem has the correct permissions:

ls -l /dev/gpiomem

crw-rw---- 1 root gpio 248, 0 May 26 15:06 /dev/gpiomem

• If not 'crw-rw----' and 'root.gpio', correct permissions:

sudo chown root.gpio /dev/gpiomem
sudo chmod g+rw /dev/gpiomem

• Confirm group membership for user pi, login as pi and run:

groups

pi adm tty dialout cdrom sudo audio video plugdev games users input netdev gpio i2c spi

• If not a member of the gpio group:

sudo adduser pi gpio

• No change

Can't open /dev/mem: Permission denied

Attempt 2

Open up /dev/mem to gpio group

• Current permissions:

ls -lart /dev/mem

crw-r----- 1 root kmem 1, 1 May 26 15:34 /dev/mem

• Change:

sudo chown root.gpio /dev/mem
sudo chmod g+rw /dev/mem

• Updated permissions:

ls -lart /dev/mem

crw-rw---- 1 root gpio 1, 1 May 26 15:34 /dev/mem

• No change

Can't open /dev/mem: Permission denied

[vitormhenrique]

Added on the new release update and test it out...

[vitormhenrique]

for documentation purposes: dma is set on the advanced section of the plugin, if empty it will use 10 as default.

[gordonturner]

Thanks @vitormhenrique! I will check it out when I do my Octoprint updates.