YFYI: p44-ledchain drive v9 now supports 16-bit WS2816 LEDs

luz

Hi Onioneers,

I just got a bunch of WS2816 LEDs, which are similar to WS2812/13 but have 16bit PWM values instead of 8bits, so should have higher brightness resolution at low levels.

To test those, I upgraded my entire LED stack to 16bit capability, which includes the p44-ledchain driver for Omega2/MT7688 and the test utility p44ledchaintest.

Spoiler: with the chips I got, the higher precision does not help that much so far, because these start to emit light only at around PWM value 200 (and unevenly so between colors and individual chips), so the actual resolution is only a little better than the 8bits we're used to from WS2812,13,15.

But still, 9 or 10 bit resolution is better than 8, and future chips will most likely improve compared with the initial version (like WS2813 -> WS2813B...)

The WS2816 chips are not yet widely available, but you can get them for example from LCSC where I got mine.

@Lazar-Demin the v9 driver is fully backwards compatible, so could be included in the Omega FW. It also is a bit more efficient in memory usage - it only allocates the internal buffers on demand for the number of LEDs actually used (the previous version allocated according to the number specified at insmod)

crispyoz

Thanks @luz ! I've was offered these LEDs here locally in Oz and was wondering about compatibility.

Lazar Demin

Cool! Thanks for the heads up @luz

I've made a github issue to track this update: https://github.com/OnionIoT/OpenWRT-Packages/issues/106

For now the plan is to make this updated driver available in the new 23.05 firmware.

Does anybody have a specific need to have this available in the older v0.3.4 firmware??

Lazar Demin

p44-ledchain driver v9 is now available as an installable package from the Onion repo!

Upgrade to firmware 23.05.3-20250121, then run opkg update; opkg install kmod-p44-ledchain

Some technical details:

The previously available p44-ledchain driver package was implemented through a patch to the OnionIoT/openwrt-buildsystem-wrapper, this patch has been removed
The new p44-ledchain v9 driver package is now built using the OnionIoT/openwrt-sdk-wrapper
To make this package installable on the device, we added new package repo to the firmware. This repo holds kernel modules compiled using the OpenWRT SDK, making it easy for Onion to publish custom kernel modules
- The repo can be found at http://repo.onioniot.com/omega2/packages/openwrt-23.05.3/core/