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Teardown and Reflashing of Tuya Smart Socket EU20A with LN882HKI Chip Analysis

bogdanelhh 16278 75
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How do I flash a Tuya EU20A smart socket with an LN882HKI chip and configure its pins for Home Assistant use?

Yes — this plug can be flashed to OpenBeken for Home Assistant by using the LN882H UART0 pins on A2/A3 (not B8/B9), pulling A9 to GND at power-on, and powering the board from an external 3.3 V supply with a common ground [#21334246][#21334409][#21832386] One successful wiring report used 3V3, GND, A9 shorted to GND during flashing, TX, and RX, and confirmed that flashing worked even though the original factory firmware could not be dumped [#21334409] For the power metering chip, the BL0937 connections were identified as CF = B4/pin 25, CF1 = B5/pin 26, and SEL = B6/pin 27 [#21799323] Another EU20A/OpenBeken template in the thread maps LED_n to 6, Btn to 7, Rel to 19, and the BL0937 signals to 20/21/22, so you can use that as a starting point if it matches your board [#21614566] After flashing, set up Wi‑Fi and then configure the pins in Config → Configure Module or in the WebApp; once metering values appear, calibrate them from the Tools tab [#21453872]
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  • #31 21597976
    p.kaczmarek2
    Moderator Smart Home  
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    Well, with some extra caution the basic testing can be done still with 230V. Just carefully probe where the low voltage should be, usually the input and the output of AMS1117-3.3V, or, in the case of the board from the first photo, VDD and GND pins.

    Of course, detach flash tool first. Otherwise you'd short mains to your PC and damage it.
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  • #32 21599283
    blacksun2
    Level 8  
    Posts: 59
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    >>21597920
    The socket in question doesn't make a sound anymore. The chip doesn't even activate when I use the contact pins.
    The same thing happens with the 19V power supply.

    I bought a whole collection of these smart sockets on AliExpress.
    There was one among them that also had a Lightning LN882HK1.
    It finally worked with that one.

    Is it still current that with an LN882H chip you have to set "Powersave 1" via autoexec.bat?
    And is it still current that you can't do this via "Startup Command Text," but only via autoexec.bat?

    I created a backup with LN882H_Flash_Dumper.py. How can you extract the Tuya OBK information from "flash.bin"? The Elektroda Flasher tool for Beken can't handle flash.bin.

    Teardown and Reflashing of Tuya Smart Socket EU20A with LN882HKI Chip Analysis

    How can I get for example the PIN-config?
    Attachments:
    • LN882HK1.zip (634.41 KB) You must be logged in to download this attachment.
  • #33 21599335
    divadiow
    Level 38  
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    blacksun2 wrote:
    How can you extract the Tuya OBK information from "flash.bin"? The Elektroda Flasher tool for Beken can't handle flash.bin.


    your dump is from a device with schema e1k70tx4 which we've seen before. Is your device template not this?:

    Code: JSON
    Log in, to see the code


    Easy Flasher cannot extract every config from dump file.

    As far as I know, this is still correct:

    Code: Text
    Log in, to see the code
  • #34 21599346
    blacksun2
    Level 8  
    Posts: 59
    Rate: 1
    divadiow wrote:

    Is your device template not this?:
    Code: JSON
    Log in, to see the code


    Easy Flasher cannot extract every config from dump file.


    ah, ok, I didn't know that. I thought Easy Flasher can extract any Tuya Templates from any dump of Tuya-devices.
    The PIN-Setting worked for the device, but it was pure coincidence that I guessed correctly.
    I ordered 10 different smart plugs from AliExpress. They were all from different retailers. The packaging and labeling don't usually reveal much. The only thing you can figure out is which original app is required, whether Tuya or eWeLink.

    would you be so kind and have a look at this dump file:
    https://www.elektroda.com/rtvforum/topic4128200.html#21599325
    It is a bk7231N and the Easy Flasher cannot extract config too.

    Big thanks.
  • #35 21602831
    blacksun2
    Level 8  
    Posts: 59
    Rate: 1
    >>21599346
    Is there a known problem with these smart Plugs with LN882H Chip and WiFi?

    Yesterday, I installed an OBK update on my plug. Since then, I've been having the problem that the plug no longer connects to the Wi-Fi network.
    At first, I thought it was a problem with the newer version of OBK and I reinstalled 1.18.131 via tx and rx and configured it newly. But the problem still persists.
    I have to plug and unplug the outlet at least 10 times before it reconnects to the Wi-Fi network. Often, but not always, the connection works as long as you don't unplug the outlet again.
  • #36 21602843
    divadiow
    Level 38  
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    I do keep hearing about such an issue. Which version did you upgrade from that worked ok?
  • #37 21602868
    blacksun2
    Level 8  
    Posts: 59
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    >>21602843

    Before the update, the device was running version 1.18.131. Then I installed the OTA.bin file for 1.18.133 (via -> config -> Wi-Fi OTA, not via web app). After that, the device stopped coming online, and the button stopped responding.
    I thought something had gone wrong with the update, so I installed 1.18.133 serially, using the bin file without OTA in the filename.
    I was wondering why the socket with the OBK, with its factory settings, wasn't sending out a Wi-Fi AP. I disconnected and reconnected the power several times. Eventually, OBK started, and I was able to integrate the socket into my Wi-Fi network and reconfigure it. Then I noticed again that the connection was lost during the configuration.
    Since I suspected a problem with 1.18.133, I was annoyed and reinstalled 1.18.131 via serial, thinking everything would be fine again. Unfortunately, that's not the case. Even with the older version, it takes countless unplugging and plugging ins before the outlet connects to the Wi-Fi. It could be a coincidence, but with 1.18.131, the connection at least doesn't drop while you're working on the web interface.

    I wouldn't swear that the outlet worked perfectly with 1.18.131 before. It could also have been a coincidence that I didn't notice the problems.

    There's also a minor flaw in the web app for OTA. The web app expects an rbl file as an update file. For LN882H, however, there are only bin files.

    What I can say, however, is that since I reinstalled and configured the outlet, the button is working again, which wasn't the case after the online update. The button works even when there's no Wi-Fi connection. This indicates that OBK is at least running.
  • #38 21607646
    Drakarah
    Level 6  
    Posts: 8
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    I've made a dump of my plug, which seems to be the same or at least very similar with the same chip. I've checked the SHA256 with the firmware that was already posted earlier in the thread and they are different.

    Flashing OpenBeken worked fine as well with the wiring instructions posted earlier in the post
    Attachments:
    • flashdump_otp.bin (1 KB) You must be logged in to download this attachment.
    • flashdump_flash.bin (2 MB) You must be logged in to download this attachment.
  • #39 21614453
    olivluca
    Level 7  
    Posts: 16
    I'm trying to get this device working with esphome (sorry folks) and I cannot get any data from the BL0937.
    Are you sure it is working with openbeken?
    The BL0937 driver uses interrupts to count the CF and CF1 pulses, but according to the datasheet only bank A can use interrupts while CF and CF1 are in bank B.

    Edit: I'd try openbeken myself but I broke the A9 pad while soldering, so I cannot flash it via serial.
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  • #40 21614460
    divadiow
    Level 38  
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    I have this running currently.
    gif
    Screenshot of OpenLN882H device dashboard displaying sensor and status data

    I can't remember if I calibrated it and I'm not sure if the reading behaviour indicates something is off, but it looks like it's working

    Added after 10 [minutes]:

    olivluca wrote:
    but I broke the A9 pad while soldering, so I cannot flash it via serial.
    could scrape some of the coating off the leading trace? like: https://www.elektroda.com/rtvforum/topic4028087-30.html#20966104

    Close-up of PCB showing exposed trace between RX and TX pins, marked with a red circle
  • #41 21614489
    p.kaczmarek2
    Moderator Smart Home  
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    @olivluca I would advice against flashing not tested solutions, especially when you can't go back easily when pads break.
    Do you have module version, or like from first post?
    Close-up of LNB821HK1 chip on PCB with a red arrow pointing at a circuit trace
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  • #42 21614514
    olivluca
    Level 7  
    Posts: 16
    divadiow wrote:

    I can't remember if I calibrated it and I'm not sure if the reading behaviour indicates something is off, but it looks like it's working


    So the datasheet is wrong then?

    divadiow wrote:

    could scrape some of the coating off the leading trace?


    It's actually like the picture posted below and I'm quite bad with a soldering iron, I'll see if I can get help from a colleague with better equipment and abilities :-D

    p.kaczmarek2 wrote:
    @olivluca I would advise against flashing not tested solutions, especially when you can't go back easily when pads break.
    Do you have module version, or like from first post?
    Close-up of LNB821HK1 chip on PCB with a red arrow pointing at a circuit trace


    Yes, it's like that, but if nobody tests untested solutions they'll never become tested ;-)
    In any case I broke the pad while re-soldering the cable to flash openbeken....
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  • #43 21614541
    divadiow
    Level 38  
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    olivluca wrote:
    So the datasheet is wrong then?


    unsure. I see this

    Interrupt pin assignment table showing PAD names GPIOA0–GPIOB9 and EXT_INT functions

    GPIO description stating 20 ports split into GPIOA and GPIOB, with interrupt mode for Group A

    my assignments:
    Screenshot of port configuration A7–B3 with dropdown selections

    Added after 11 [minutes]:

    are external interrupts a different thing? I don't know enough..
  • #44 21614566
    olivluca
    Level 7  
    Posts: 16
    In your configuration both CF and CF1 are in bank A, in this device (according to the json in the first page which I copied here) are in bank B, it's a different device.

    Code: text Expand Select all Copy to clipboard
    
{
  "vendor": "Tuya",
  "bDetailed": "0",
  "name": "ISPTEC Tuya Smart Socket EU16/20A Wifi Smart Plug With Power Monitoring",
  "model": "EU20A",
  "chip": "LN882H",
  "board": "TODO",
  "flags": "1024",
  "keywords": [
    "LN882HKI",
    "BL0937"
  ],
  "pins": {
    "6": "LED_n;0",
    "7": "Btn;0",
    "19": "Rel;0",
    "20": "BL0937CF;0",
    "21": "BL0937CF1;0",
    "22": "BL0937SEL;0"
  },
  "command": "",
  "image": "https://obrazki.elektroda.pl/YOUR_IMAGE.jpg",
  "wiki": "https://www.elektroda.com/rtvforum/topic4091325.html"
}


    Added after 3 [hours] 59 [minutes]:

    It turns out that, in spite of the documentation, even GPIOs of bank B can generate interrupts. I fixed the problem in libretiny with this modification.
    I found the missing calls by looking at the BL0937 driver in OpenBeken, so thank you.
  • #45 21619377
    brazoayeye
    Level 4  
    Posts: 19
    Oh, I probably cooked my plug.
    I welded as described and all worked well till I grounded A9. When I did it usb device had an overcurrent, the cpu became very hot and stopped blinking the led.

    Maybe welding I also grounded the near capacitor, or is it because I grounded A9 with the 3v3 connected?
  • #46 21619424
    olivluca
    Level 7  
    Posts: 16
    brazoayeye wrote:
    Maybe welding I also grounded the near capacitor, or is it because I grounded A9 with the 3v3 connected?


    It depends: if you shorted the side of the capacitor near the chip then, yes, you shorted 3.3V to ground. If you shorted the other side it's already ground. In fact one of the pins (in theory) is 1.1V output from the chip, so if you shorted it to ground you probably destroyed the chip.
  • #47 21640103
    earurelay
    Level 6  
    Posts: 10
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    Hi guys,

    Did convert two EU20A plugs to openBk and it worked flawlessly!

    Thanks!

    Screenshot of openBk interface for EU20A socket showing energy measurements

    By the way, I ordered one EU20A and one EU16A. Inside they are strictly identical. Good to know :)
  • #48 21640106
    p.kaczmarek2
    Moderator Smart Home  
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    Even the relay rating?
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  • #49 21640155
    earurelay
    Level 6  
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    >>21640106 Yes, 20A for each relay. Same model and reference also.

    I found absolutely no difference (passive and active components are exactly identical on both PCB). I even checked each resistor, diode, ... The same ! :)
  • #50 21640189
    p.kaczmarek2
    Moderator Smart Home  
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    It reminds me of what I've seen when testing LD25/LD35 Chinese dummy loads.
    https://www.elektroda.com/rtvforum/topic3494513.html#17412016
    So... it seems that in this case it's better to buy 16A version? What were the prices?
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  • #51 21645645
    derKeks
    Level 3  
    Posts: 14
    Thank you @bogdanelhh for being the pioneer. Your guide helped me a lot and I could successfully flash one of my smart plugs. Different brand/name but the same circuit.

    @divadiow @max4elektroda @p.kaczmarek2 I don't know whether I should start a new thread or just post here because I have a "problem" with the same unit shown in this thread:
    I flashed and set up Wi-Fi/pins config. The web interface shows real-time values. So far so good. (side note: I did not integrate it in HA yet). Currently I am investigating the AP mode. I can go into AP mode via webapp command but I cannot enter AP mode by 5 times power cycle nor long pressing. When I enter the AP mode via webapp command the LED on the smart plug is not blinking! It does not show that it is in AP mode. I can see on my smartphone that the AP is created but the LED is not blinking.

    Maybe I don't need the feature to see whether AP mode is on or off by the LED but the feature to enter AP mode is useful in some circumstances. Especially if you have to set them up and somehow they don't connect to Wi-Fi and you cannot enter AP mode to rescue it.

    Do you know why my smart plug does not enter the AP by pressing the hardwired button? Or why does it not show the AP mode by a blinking LED?

    Side note: I used an old Raspberry Pi 3 for flashing. I think many people have an old Pi somewhere lying around. Good alternative instead of buying an UART adapter ^^
  • #52 21645677
    max4elektroda
    Level 24  
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    Regarding the problem of safe mode failing (5 unsuccessful boots) I can only imagine that not all reboots where counted because the online time was to long (and it was interpreted as successful) or the reboot was so fast, it was not yet seen as start.
    The LED will follow the settings for the pin in the config page. Maybe there's an issue? Will it change color after plug connected to your WiFi?
    To be honest I'm not sure if pressing button for long is configured to enter AP mode.
  • #53 21645794
    p.kaczmarek2
    Moderator Smart Home  
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    Maybe there are capacitors on the board and you do not wait long enough for them to discharge.

    We don't support "AP mode by long button press", because when I tested Tasmota in the past, this feature was breaking my devices while testing pins - it happened several times, I remember setting wrong button pin and getting fake "long press" tasmota events which then were resetting my Tasmota device to factory settings. Very annoying.
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  • #54 21646024
    derKeks
    Level 3  
    Posts: 14
    Okay, I have troubles understanding what to do to bring a flashed device into AP mode by using the physical button.

    When I have an unflashed Tuya device I only get into AP mode by long pressing. Somehow 5 power cycles do not work anymore ^^ or I don't know what that means.

    But the flashed device is not able to get into AP mode by the physical button.


    Maybe my timing is wrong in the 5 power cycles. Can you explain or show me a video about this?


    Tasmota interface showing power and device status from BL0937
  • #55 21646083
    max4elektroda
    Level 24  
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    There is no function, like in Tuya, to enable the AP mode by physical button.

    So if device is accessable, you should use the GUI to enabe AP

    If device is unaccessable, the SAFE MODE can be accessed by fast reboots 5 times in a row (it needs to be restarted during the first 5 seconds)
    One easy way is to cascade two plugs, so you can power/power off the second one fast with the first ones button, without physicaly unplugging it.
  • #56 21646094
    derKeks
    Level 3  
    Posts: 14
    Thank you so much. It works as you described! Now I understand the difference between handling a Tuya device and an Openbkn device. My problem was that I used the physical button instead of unplugging the device or toggling the power supply.

    My problem is solved. :)
    (Unfortunately I cannot vote your post as helpful, I am too new :D )
  • #57 21646192
    p.kaczmarek2
    Moderator Smart Home  
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    Ah I see... you've assumed that "turn off and on the power" means toggling the relay? No, that refers to power of the whole device - so WiFi module can reboot. Maybe we should clarify that in our docs...
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  • #58 21646204
    derKeks
    Level 3  
    Posts: 14
    >>21646192 Yeah, the docs were not clear or obvious. I read different threads with multiple guide links and how-tos. many times "5 times power cycle" were mentioned to enter AP mode. I did not realize that AP mode equals safe mode and is different to the stock device. I did not know where to find or read generic documentation/instructions in the beginning. just now i stumbled upon this link:
    https://github.com/openshwprojects/OpenBK7231T_App/tree/main/docs


    If I would have found the previous link earlier I would have stumbled over the safe mode. So I think this fault is on my side.

    but to answer your question: yes, I think the section "safe mode" is not clear enough. I think it would be a good idea to add the information that you must not use the device on/off switch. either unplugging or using your method with a switch in series to act as unplugger.

    I am so glad about this whole project. I was scared that my HA will be inconsistent with the shitty tuya integration. Especially when I saw that Tuya is not compatible anymore. luckily the LN chip is still compatible. so glad! thank you very much for your contribution

    PS: I did not use any instructions from the docs :D flashing.md does not contain my way. I guess there are many ways to achieve the same goal. I used https://github.com/mandl/LN882Loader on my Raspberry Pi.
  • #59 21796414
    GoldMember
    Level 12  
    Posts: 26
    Rate: 1
    Hi,
    I bought recently two smart plugs on LN882H and I can't flash them with OpenBeken. Here is log from Easy Flasher:

    Loaded 805584 bytes from firmwares/OpenLN882H_1.18.233.bin...
    Now is: piątek, 2 stycznia 2026 13:36:27.
    Flasher mode: LN882H
    Going to open port: COM3.
    Port ready!
    Sync with LN882H...
    sending version... waiting for: Mar 14 2021/00:23:32
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32
    Still no reply - maybe you need to pull BOOT pin down or do full power off/on before next attempt
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32
    Unknown command 'version'sending version... waiting for: Mar 14 2021/00:23:32

    What is wrong?
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Topic summary

✨ The discussion focuses on the teardown and reflashing process of the Tuya Smart Socket EU20A, which uses the LN882HKI chip and supports power monitoring via the Smart Life app with Google Assistant and Alexa integration. The original poster successfully soldered wires to the chip's UART pins (notably A9 to GND for download mode) and flashed the device using an external 3.3V power supply and a CH340 USB-to-serial adapter. Key UART pins identified include RX0/TX0 on A3/A2 (pins 11 and 10) and RX1/TX1 on B8/B9. The reflashing process involves entering download mode by pulling A9 to ground, with LED behavior indicating mode status. Users reported challenges with unstable web configuration interfaces and long firmware dump times (~40 minutes). A configuration template was shared, mapping pins for LED, button, relay, and BL0937 power metering chip signals. Calibration of the BL0937 chip is necessary for accurate power measurement, achievable via the device's web app tools. Backup of original firmware before flashing is recommended but often difficult due to instability. Alternative flashing methods and device variants with different chips (e.g., T34, BK7231N) were noted, with OpenBeken firmware supporting multiple chipsets. Practical advice includes using short cables, lowering serial baud rates (e.g., 115200 or 921000), and ensuring solid ground connections to improve flashing reliability. The community provided links to related resources, firmware repositories, and configuration guides to assist in reflashing and configuring the device for custom use cases such as solar panel energy monitoring.
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FAQ

TL;DR: For Home Assistant users, this EU20A teardown confirms a 2MB flash LN882HKI plug can be reflashed by UART, and “A9 pulled to ground at power-on” is the key step. Use external 3.3V, wire RX/TX to the correct serial pins, then load the BL0937 pin map for power readings. [#21334409]

Why it matters: This thread turns a hard-to-identify Tuya smart plug into a documented OpenBeken target, including wiring, boot mode, pin mapping, and the most common failure fixes.

Topic Tuya stock firmware OpenBeken on LN882H
Pairing/recovery method Long-press style pairing behavior discussed by users Safe mode after 5 fast power reboots within the first 5 seconds
Power monitoring Native in stock app Works after BL0937 pins are mapped and calibrated
Flashing entry Not applicable A9 must be tied to GND at power-on
OTA file expectation Normal vendor flow Users reported LN882H uses .bin, while WebApp expected .rbl

Key insight: Successful flashing is only half the job. On LN882H plugs, power monitoring appears only after you identify the BL0937 CF, CF1, and SEL lines and assign them to the right GPIOs.

Quick Facts

  • The opened EU20A sample used an LN882HKI in QFN-32 with 2MB flash and a stated operating range of -40°C to 105°C. [#21333751]
  • The working OpenBeken template posted for EU20A mapped pin 6 = LED_n, 7 = Btn, 19 = Rel, 20 = BL0937CF, 21 = BL0937CF1, and 22 = BL0937SEL. [#21335189]
  • A successful dump taken by the web method took about 40 minutes, and another user confirmed that duration was normal for this approach. [#21416338]
  • Users improved flashing reliability by shortening wires from about 60 cm + 20 cm and lowering UART speed to 921000 or even 115200 when errors appeared. [#21451913]
  • A related LN882H variant used BL0937 pin 6→LN882H pin 25, 7→26, and 8→27, which then worked as CF=B4, CF1=B5, SEL=B6. [#21799323]

1. How do I flash a Tuya Smart Socket EU20A with an LN882HKI chip using OpenBeken and UART wiring?

Flash it over UART with external 3.3V and the LN882H in download mode. 1. Solder GND, 3.3V, RX, TX, and A9. 2. Tie A9 to GND, then power the board so it enters download mode. 3. Flash OpenBeken, reboot normally, then configure the module pins for relay, LED, button, and BL0937. One working wiring report used red=3.3V, gray=A9, green=TX, white=RX, plus a common ground. The user explicitly said external 3.3V with common ground was used. [#21334409]

2. Which LN882H pins should I use for RX, TX, 3.3V, GND, and boot mode on the EU20A smart plug?

Use A3 as RX0, A2 as TX0, GND and 3.3V from the board supply points, and A9 as the boot strap. A correction in the thread states A3/A2 are the serial pins, while B8/B9 are RX1/TX1 and will mislead flashing attempts. For power, users either soldered directly to 3.3V and GND pads or used the AMS1117 regulator points. Boot mode requires A9 connected to GND during power-on. [#21334246]

3. Why does pulling A9 to GND at power-on put the LN882H into download mode, and what LED behavior should I expect?

Pulling A9 to GND at power-on selects the LN882H download mode instead of normal firmware boot. Users confirmed that if the plug still boots Tuya firmware, the LED flashes normally and you are not in download mode. A dim blue LED that stays on was described as correct behavior for download mode on one setup. If the LED blinks as usual, recheck ground continuity and fully remove power between retries. [#21451913]

4. What is the BL0937 chip in these Tuya smart plugs, and how does it handle power monitoring?

“BL0937” is an energy-metering IC that outputs pulse signals for electrical measurements, with separate CF, CF1, and SEL lines. In this plug family, OpenBeken reads those lines after you assign them to the correct GPIOs. The thread shows BL0937 is the dedicated power-monitoring chip on the EU20A board, and users only got voltage, current, and power data after tracing or importing the correct pin map. [#21333751]

5. Where do I import or enter the OpenBeken pin template for the EU20A: Configure Module or the Web Application?

You can do it in either place. The thread says a posted template can be imported through the WebApp, and the same pin roles can also be entered manually in Config → Configure Module on the device. If you do not know the pins, the WebApp also offers Pin Doctor for discovery. For this EU20A family, users shared a ready template, which is faster than mapping each pin from scratch. [#21453872]

6. How should I calibrate BL0937 power readings in OpenBeken after flashing an LN882H-based smart plug?

Calibrate it after the BL0937 pins already produce live values. The thread says you should first assign CF, CF1, and SEL correctly; once the device shows readings, even rough ones, use the Tools tab in the WebApp to calibrate the power metering. That sequence matters because calibration is pointless if the pulse pins are wrong or inactive. Users specifically described calibration as the step after functional pin setup, not before. [#21453872]

7. What causes Easy Flasher on LN882H to show repeated "Unknown command 'version'" errors, and how do I fix it?

That error usually means the chip never entered LN882H download mode. In the January 2, 2026 report, Easy Flasher kept repeating “Unknown command 'version'” until the user realized A9 was not tied to GND at power-on. After connecting A9 to GND correctly, flashing succeeded. If you see that exact loop, fix boot strapping first before changing firmware files or templates. [#21796709]

8. Why might an LN882H smart plug flash successfully but show no voltage, current, or power readings until the BL0937 pins are traced?

Because OpenBeken can boot and switch the relay before power metering is configured. The thread shows several cases where flashing worked, Wi‑Fi worked, and the plug web UI loaded, but voltage and power stayed empty until the BL0937 CF, CF1, and SEL lines were traced to the LN882H GPIOs. One later variant only worked after mapping BL0937 pins 6, 7, and 8 to LN882H pins 25, 26, and 27. [#21799323]

9. When flashing an LN882H socket with a CH340 adapter, what serial speed, wire length, and power supply setup work best?

Use short wires, reduce baud rate if needed, and avoid relying on weak USB-UART power alone. One user failed with long leads of about 60 cm + 20 cm, then succeeded after shortening them and dropping speed to 921000. Another recommendation was to try 115200 if higher rates were unstable. Multiple posts also stress using a solid external 3.3V supply with common ground, because some adapters cannot power the board reliably. [#21453808]

10. What is OpenBeken safe mode, and how is it different from Tuya's AP pairing mode on a smart plug?

OpenBeken safe mode is a recovery boot path, not Tuya-style pairing mode. Tuya users often expect AP mode from a long button press, but OpenBeken on this plug does not use that behavior. Instead, the thread says safe mode is triggered by 5 fast power reboots, each within the first 5 seconds of startup. Safe mode is for recovering access when the device is otherwise unreachable, while Tuya AP mode is the stock pairing flow. [#21646083]

11. How do I force an OpenBeken-flashed smart plug back into AP or safe mode if the physical button does not do it?

Use the web GUI if the device is reachable, or use repeated full power cuts if it is not. 1. If the plug is online, enable AP from the GUI. 2. If it is offline, cut mains power to the whole device and restore it quickly 5 times. 3. Do each reboot within the first 5 seconds so OpenBeken counts them as failed boots. The relay button does not count, because it does not reboot the Wi‑Fi module. [#21646083]

12. Why do some LN882H plugs lose Wi-Fi or fail to reconnect after an OTA update, and what troubleshooting steps are worth trying?

The thread reports intermittent LN882H Wi‑Fi reconnect issues after OTA, but no single root cause was confirmed. One user updated from 1.18.131 to 1.18.133 and then needed many unplug/replug cycles before Wi‑Fi returned. Practical steps from the discussion are: reflash by serial, reconfigure from scratch, verify the button still works locally, and test whether the issue persists across versions. That narrows whether the failure came from OTA state, configuration corruption, or an existing instability. [#21602868]

13. What is the PowerSave command on LN882H, and why does the thread say it should be placed in autoexec instead of Startup Command Text?

“PowerSave” is a startup power-management command that changes the LN882H sleep behavior, with level 1 used for light sleep when BL0937 metering is present. The thread says LN882H does not apply this command correctly from Startup Command Text, so users should place PowerSave 1 in autoexec instead. It also notes that values above 1 trigger deeper sleep, while PowerSave 0 disables the feature. [#21599335]

14. OpenBeken vs ESPHome on an LN882H smart plug with BL0937: which approach is more practical for power monitoring and Home Assistant?

OpenBeken is the more practical choice in this thread because it is already proven on the EU20A hardware. Multiple users flashed LN882H successfully, posted working pin templates, and showed BL0937 readings in the OpenBeken interface. By contrast, the ESPHome attempt raised a real interrupt concern for BL0937 on bank B pins, and the user only fixed it later by modifying LibreTiny. If you want the fastest path to Home Assistant, OpenBeken has the shorter path here. [#21614566]

15. What safety precautions should I follow when soldering to A9, A2, A3, or the AMS1117 regulator on a mains-powered smart plug?

Never flash or probe this plug while it is connected to mains. The clearest warning in the thread says flashing should NEVER be done with the plug on high voltage. Use isolated low-voltage power only, and be careful around A9 and nearby capacitors because a mistaken short can overcurrent USB power, overheat the chip, or kill the board. For AMS1117 access, the thread identifies pin 1 as GND, pin 2 as +3.3V, and pin 3 as 5V input on one related LN882H board. [#21832386]
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