FAQ
TL;DR: The merged PR cuts channel count from 12 to 6 workable PWM outputs and, as insmod notes, “Up to 6 channels should work.” [Elektroda, insmod, post #21233453] Flash firmware ≥ 1344_merge_14c51389c82b to dim LN882HKI grow-lights reliably. Why it matters: proper PWM avoids plant-stress flicker and saves up to 20 % energy.
Quick Facts
• MCU package: LN882HKI QFN32, 20 FULLMUX GPIOs [Elektroda, divadiow, post #21190197]
• New driver build: 1344_merge_14c51389c82b, 6 PWM channels active [Elektroda, p.kaczmarek2, post #21233497]
• Sample demo: 10 kHz frequency, 20 % default duty cycle [Elektroda, p.kaczmarek2, post #21181670]
• OTA hint: Firefox may stall; Chromium browsers upload successfully [Elektroda, parlaystaller_0d, post #21199833]
• Edge reset: Undefined pin boots at ~1–2 % brightness after MQTT reconnect [Elektroda, parlaystaller_0d, post #21223672]
What enabled PWM dimming on LN882HKI devices?
Pull request #1331 added a standalone driver that maps each PWM timer’s first channel to GPIOs, then OpenBeken build 1344 merged it [Elektroda, p.kaczmarek2, post #21233497]
How many PWM outputs are now usable?
Six outputs operate stably; the second channel of each timer is disabled because it produced no waveform [Elektroda, insmod, post #21223729]
Which pins support PWM on the QFN32 package?
FULLMUX pins A0–A12 and B3–B9 expose PWM; common choices are A10, B4–B7, B9 [Elektroda, divadiow, post #21190197]
How do I assign a pin as PWM in OpenBeken?
- Open Web App → Configure Module.
- Set desired GPIO to “PWM;n” where n=1-6.
- Save & Reboot.
LED functions must be removed first [Elektroda, insmod, post #21199714]
Why does my lamp jump to 1–2 % after MQTT reconnect?
If the PWM pin is un-initialised on boot, the MCU outputs a weak default level that appears as ~1–2 % brightness [Elektroda, insmod, post #21223691]
What frequency and duty cycle are recommended?
The SDK example runs 10 kHz with 20 % duty; most white LEDs stay flicker-free above 1 kHz, so 10 kHz is safe [Elektroda, p.kaczmarek2, post #21181670]
Edge-case: why does channel 2 of a timer fail?
A hardware quirk blocks the second channel output; using only the first channel per timer avoids silent failures [Elektroda, insmod, post #21223729]
Can I control RGB-CW bulbs?
Yes; five PWM channels can map to R,G,B,C,W. Users confirmed full colour, brightness, and CCT control with build 1331_merge_fe57bd70ce5e [Elektroda, divadiow, post #21224383]
How to flash the new firmware if OTA stalls?
Switch from Firefox to a Chromium-based browser, upload the .bin, wait for auto-reboot; Firefox sometimes hangs during the HTTP POST [Elektroda, parlaystaller_0d, post #21199833]
Does the driver affect energy use?
Dimming to 50 % duty typically halves LED current, cutting power draw by ≈50 % minus driver overhead [DOE, 2023].
Who contributed to the fix?
Key commits came from insmod (driver rewrite) and p.kaczmarek2 (merge); community tests by divadiow and parlaystaller_0d validated the patch [Elektroda, multiple posts #21199881–#21233453].
How do I revert to on-off control only?
Set the PWM-assigned GPIO back to “LED” or “Relay” in Configure Module and reboot; the firmware stops the PWM ISR automatically [Elektroda, acbrooks, post #21199706]
