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[BK7231N / CB2S BL0937] Elivco EU Smart Plug 20A BL0937 RMC021

miegapele 6768 13
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  • #1 20691922
    miegapele
    Level 16  
    Posts: 173
    Help: 15
    Rate: 29

    Bought some cheap sockets from AliExpress Elivco store, with the intention to cut from the cloud.
    This one is a 20A smart socket marked RMC021, which was not previously shown here.
    Wi-Fi smart plug model RMC021 with technical specifications on the casing.
    White Elivco Tuya EU 20A smart plug with power button.
    It opens from the back quite easily, just need to work the seam loose with the spudger.
    Disassembled Elivco 20A smart plug
    My soldering skills are way too weak to try to desolder and see if the relay is rated for 20A, but anyway I would not recommend using it for that even if it is :).
    It contains the usual BK7231N / CB2S BL0937 chips.
    The board seems to be the same as for RMC004, which has a teardown already.
    Electronic circuit board with components like capacitors and resistors.
    BK7231N is hard to make a picture with my phone, that's the best I can.
    Close-up of an electronic module with BK7231N chip on a circuit board.
    Usual BL0937 and BP2525 chips
    Close-up of a circuit board with electronic components, including the BP2525 chip. Close-up of an electronic circuit board with various components, including a small chip.

    Flashed with tyua-cloudcutter using Firmware 1.1.8. Did not check the firmware in the app. Flashing was rather difficult, was stuck on the last step, but it might be because of my trashy Wi-Fi adapter. It seems after flashing goes to the last step it's no longer possible to reconnect to Tyua, at least I was not able to. And it had a non-Tyua AP at that point.
    Config seems to be like this, not completely sure if all the power values match, but button, relay, LED, and active power look correct:
    Code: text Expand Select all Copy to clipboard
    
{
  "vendor": "Tuya",
  "bDetailed": "0",
  "name": "Elivco Tuya EU Smart Plug 20A",
  "model": "RMC021",
  "chip": "BK7231N",
  "board": "TODO",
  "flags": "1024",
  "keywords": [
    "TODO",
    "TODO",
    "TODO"
  ],
  "pins": {
    "6": "BL0937CF1;0",
    "7": "BL0937CF;0",
    "8": "LED_n;1",
    "10": "Btn;1",
    "24": "BL0937SEL;0",
    "26": "Rel;1"
  },
  "command": "",
  "image": "https://obrazki.elektroda.pl/YOUR_IMAGE.jpg",
  "wiki": "https://www.elektroda.com/rtvforum/topic_YOUR_TOPIC.html"
}

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    #2 20692730
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14394
    Help: 650
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    Thanks, it's good to see you managed to flash it successfully. That kind of plug is usually problematic due to the way it's constructed, the access to bottom side of the board is very problematic.

    I always prefer to buy LSPA9 models: https://www.elektroda.com/rtvforum/topic3887748.html
    They are easier to disassemble and to flash by wires.

    Now, you can finalize configuring your device:
    - calibrate power metering
    - enable power save with PowerSave 1 command in startup command field (or autoexec.bat)
    - you can also start SSDP driver to make it discoverable by Windows: https://www.youtube.com/watch?v=aDZseGQSl-8
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  • #3 20693284
    miegapele
    Level 16  
    Posts: 173
    Help: 15
    Rate: 29

    p.kaczmarek2 wrote:
    I always prefer to buy LSPA9 models: https://www.elektroda.com/rtvforum/topic3887748.html
    They are easier to disassemble and to flash by wires.

    I did buy a few of them, will try to flash today.

    p.kaczmarek2 wrote:
    Enable power save with PowerSave 1 command in the startup command field (or autoexec.bat)

    Will this help much? I think the relay still eats most of the power (if enabled). These plugs use around 0W with the relay off, and about 1W with the relay on.
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  • #4 20693289
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14394
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    PowerSave 1 is strongly recommended because the chinese products are often designed without any safety margin and using them without PowerSave can wear out electrolytic capacitors too quickly. Those are low quality, low cost products.

    See here for a short repair report of smart device with leaked electrolytic capacitor:
    https://www.elektroda.pl/rtvforum/topic3898805.html
    OBK PowerSave is optimized to prevent that.
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  • #5 20693335
    miegapele
    Level 16  
    Posts: 173
    Help: 15
    Rate: 29

    Thank you, added backlog PowerSave 1 command to startup. Need to check how much it improves power consumption.
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  • #6 20693337
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14394
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    Keep in mind that dynamic power saving may be hard to track, especially that it can be affected by things like Web App Log tab open or by DTIM setting on your router (the refresh frequency of WiFi, one could say, in a big implications).
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  • #7 20711002
    lvnorse
    Level 3  
    Posts: 4

    >>20691922
    Hmm, strange. I have the same RMC021, but it is BL602 BL0937 combo. Yes, the power monitor shows zero BL602 BL937 combo, I guess.

    Power monitor screen displaying voltage, current, and power information.

    Wi-Fi smart plug RMC021 with open casing revealing internal electronics. Close-up of a circuit board with markings and a chip. Close-up of a green circuit board with integrated circuits and other electronic components.
  • #8 20711217
    p.kaczmarek2
    Moderator Smart Home  
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    BL0937 driver for BL602 must be finished first:
    https://github.com/openshwprojects/OpenBK7231T_App/pull/862
    If you know coding, you can help us. You only need to setup on change interrupt to count edges
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  • #9 20711344
    lvnorse
    Level 3  
    Posts: 4

    Ok, I think I understand what you mean. The driver is not finished for BL602.

    Code: text Expand Select all Copy to clipboard
    #if PLATFORM_W600
static void HlwCf1Interrupt(void* context) {
	tls_clr_gpio_irq_status(GPIO_HLW_CF1_pin);
	g_vc_pulses++;
}
static void HlwCfInterrupt(void* context) {
	tls_clr_gpio_irq_status(GPIO_HLW_CF_pin);
	g_p_pulses++;
}
#else
void HlwCf1Interrupt(unsigned char pinNum) {  // Service Voltage and Current
	g_vc_pulses++;
}
void HlwCfInterrupt(unsigned char pinNum) {  // Service Power
	g_p_pulses++;
}
#endif

    W600 is for Winner Micro.
    "else" is for Beken.
    But for Bouffalo Lab, there needs to be a separate interrupt.
  • #10 20711347
    p.kaczmarek2
    Moderator Smart Home  
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    Yes, someone needs to search the SDK for code samples here:
    https://github.com/openshwprojects/OpenBL602
    and integrate BL602 interrupt.

    I remember that I tried to do it in the past, even tough I don't have BL602+BL0937 combo, but had some issue, maybe with compilation or smth....
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  • #11 20711511
    lvnorse
    Level 3  
    Posts: 4

    Did check Bl602 specs it is RISC-V
    Quote:
    64 interrupts, interrupt controller with 16 interrupt levels/priorities for low-latency interrupt processing, support for external Flash


    Quote:
    BL602/BL604 supports internal RTC wake-up and external interrupts wake-up.
    CPU interrupt controller supports stack/nesting, level/pulse, and high/low active.


    and did find nice implementation of interrupts with LoRa module Here

    I hope I'm up for the task, just need to set up the compiler.
  • #12 20711517
    p.kaczmarek2
    Moderator Smart Home  
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    Actually it is easier than that. You don't need to setup compiler, you can use our online builds. They work even in pull requests. I may need to accept them first, but once I do it, you will get binaries built online.
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  • #13 20711943
    lvnorse
    Level 3  
    Posts: 4

    Does not seem it's so easy, just added some lines, it's a lot of reading. I think enough for today. Also, some other guy has the same issue and is working on it.
  • #14 20733641
    ireneuszsto
    Level 1  
    Posts: 1
    Board Language: polish
    I bought it on Ali with the hope of Suplating. However, so far I have not even opened it. :-) .
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Topic summary

✨ The discussion revolves around the Elivco EU Smart Plug RMC021, a 20A smart socket purchased from AliExpress, which utilizes BK7231N and BL0937 chips. Users share experiences regarding the disassembly and flashing of the device, noting that the construction can complicate access to the board. Recommendations include using the PowerSave 1 command to enhance power efficiency and prevent premature capacitor failure, as these devices often lack safety margins. Some users report variations in chip combinations, such as BL602 with BL0937, and discuss the need for driver development for these configurations. The conversation also touches on the challenges of coding and integrating interrupts for the BL602 chip.
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FAQ

TL;DR: BL602 supports 64 interrupts, and "CPU interrupt controller supports stack/nesting." This FAQ helps Elivco RMC021 owners flash, configure, and fix power metering. [Elektroda, lvnorse, post #20711511]

Why it matters: BL602 units can read zero power until interrupts are handled, and PowerSave reduces stress on low-cost PSU caps.

Quick Facts

What chips are in the Elivco RMC021 (BK7231N version)?

Teardowns show a CB2S module with BK7231N, a BL0937 energy monitor, and BP2525. The case opens from the back with a spudger. The PCB appears similar to the RMC004 board. Avoid assuming the relay safely handles 20 A continuously. [Elektroda, miegapele, post #20691922]

Does the RMC021 also come with BL602?

Yes. A reported RMC021 unit uses a BL602 MCU paired with a BL0937 meter. The power monitor initially showed zero readings on that combo, prompting driver work. Photos confirm the BL602-based board layout. [Elektroda, lvnorse, post #20711002]

Why does power monitoring show zero on BL602 + BL0937?

The BL0937 driver for BL602 needs proper GPIO edge interrupts. Without that, pulses are not counted, so readings look like zero. The maintainer noted the driver must be finished and invited contributions. "You only need to setup on change interrupt to count edges." [Elektroda, p.kaczmarek2, post #20711217]

How do I flash the RMC021 with Cloudcutter?

One user flashed with tuya-cloudcutter on firmware 1.1.8. The process stalled at the last step, and reconnecting to Tuya AP failed. The device broadcast a non‑Tuya AP afterward. Be patient and verify your Wi‑Fi adapter stability. [Elektroda, miegapele, post #20691922]

What OpenBK pin mapping worked for BK7231N RMC021?

Example mapping: P6=BL0937CF1, P7=BL0937CF, P8=LED_n, P10=Button, P24=BL0937SEL, P26=Relay. The setup drove button, relay, LED, and active power correctly. Treat it as a starting point and calibrate. [Elektroda, miegapele, post #20691922]

How do I reduce idle heat and extend life on these plugs?

Enable PowerSave 1 in OpenBK. The author warns low-cost devices lack margin, which stresses electrolytic capacitors. "PowerSave 1 is strongly recommended" and helps prevent premature capacitor failure. It’s a simple, high‑impact setting. [Elektroda, p.kaczmarek2, post #20693289]

How much power does the RMC021 use at idle?

Measured consumption was ~0 W with the relay off, and about 1 W with the relay on. That highlights why PowerSave matters most when the relay is energized. Test your unit to confirm. [Elektroda, miegapele, post #20693284]

How do I enable PowerSave 1 at boot? (3 steps)

  1. Open OpenBK’s Startup Command field or autoexec.bat.
  2. Add: backlog PowerSave 1
  3. Save and reboot to apply power saving automatically. [Elektroda, p.kaczmarek2, post #20692730]

How should I calibrate the power metering?

Calibrate after flashing. Use the firmware’s power calibration with a known load to align BL0937 readings. The maintainer lists calibration as a next step for accurate metering. Keep loads resistive for best results. [Elektroda, p.kaczmarek2, post #20692730]

Why might my power‑saving measurements vary over time?

Dynamic power saving can be hard to track. The Web App Log tab and router DTIM settings affect Wi‑Fi activity and draw. Close verbose pages and check DTIM if numbers fluctuate. This behavior is expected. [Elektroda, p.kaczmarek2, post #20693337]

Is there a plug that’s easier to open and wire‑flash than RMC021?

Yes, consider LSPA9 models. The maintainer prefers them. "They are easier to disassemble and to flash by wires." This saves time and reduces damage risk while modding. [Elektroda, p.kaczmarek2, post #20692730]

Can I safely run 20 A through this plug continuously?

Treat the 20 A label cautiously. The teardown author did not verify relay rating and advised against using it at 20 A. Thermal and component limits may be tight in budget hardware. [Elektroda, miegapele, post #20691922]

Is the RMC021 PCB similar to the RMC004?

Yes. The RMC021 board appears the same as RMC004 in the shared teardown. That helps reuse known configs and tips from the earlier model. Visual inspection supports this note. [Elektroda, miegapele, post #20691922]

How do I make the plug discoverable in Windows?

Start the SSDP driver in OpenBK. This enables network discovery by Windows. The maintainer explicitly recommends it and provides a demo video. "You can also start SSDP driver to make it discoverable by Windows." [Elektroda, p.kaczmarek2, post #20692730]
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