LN882H Bulb Flashing but No Serial Communication via u0/u1 TX RX—What to Check?

No connection to LN882H - bulb flash (brand unknown)

Not done these particular ones before, and I can’t get any comms from it. Got everything wired up as per the guides; it’s very similar to others, only requiring a boot pin to ground out.
I’m using U0 RX and U0 TX as that’s what you flash via, right?
Even so, no serial comms on U1 RX/TX too.
Any ideas what I could be doing wrong? These should be relatively simple as they are in Easy Flasher

Can you show photos? Did you actually flashed other LN882H devices with your current setup?


The common issues are:
- too long wires
- missing common ground
- swapped RX/TX
- bad power supply
- interference on RX/TX (like, something is connected there on the board
etc etc

I’ve done a fair few devices onto the various “Open” platforms now - bl602, esp8266, RDA, esp32, obk7231t/N, rtl8720.

Flashing setup's the same as it has been for about 3 devices I’ve done this morning, mostly 8266s.



Excuse colours — I don’t have any colour‑coded DuPont cables on me

Added after 2 [minutes]:

Red is going to 3.3 V, purple to cen (and grounded?)

Green is TX, so going to RX on TTL
White is RX, going to TX on TTL

Have tried switching them around. No change

Blue is ground.

Can cap placements interfere with flashing? Sure — I heard that in the Ln882h guide video

>>21730338
CEN is used to reset chip, not to put it in boot mode.
I guess P21 is a boot1 pin, so it should be grounded instead.

Thank you — it's being held in reset then. I'm attempting to get a few of these done today. I'll report back shortly when I've soldered it up.
Hope it works!

Added after 17 [minutes]:

That was the issue — thanks!

Added after 7 [hours] 22 [minutes]:

Interestingly I dont get any LEDs firing at all here. Connects to wifi etc, web UI up etc but using GPIO Finder and firing all GPIO outputs to I dont get even a glimmer from the leds..