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[BL602/BL0937] Yet another Smart Socket 20A (but 16A)

flobuljeedom 17637 117

TL;DR

  • An Aubess smart plug from AliExpress uses an SM-028_V1.3 board with a BL602L02 chip and BL0937 power-monitoring IC.
  • The module was flashed with Bouffalo Lab Dev Cube through soldered FTDI232L connections on RX, TX, 3V3, and GND, with BT tied to VCC through 10 kΩ.
  • BL0937 CF1 connects to GPIO3, CF to GPIO14, SEL to GPIO21, LED to GPIO20, relay to GPIO2, and button to GPIO17.
  • Wi‑Fi setup succeeded after flashing, but the web app still shows zero power values, suggesting the BL0937 driver or HAL interrupt handling is still incomplete.
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  • I bought a Smart Plug from Aliexpress: https://fr.aliexpress.com/item/1005005790622741
    They are named Aubess on the website, but not on the packaging or on the socket.

    Smart plug and its packaging from AliExpress. Smart plug and its packaging on a dark surface.

    Easy to open with pliers.
    Dismantled Smart Plug with visible circuit board.

    Contains an SM-028_V1.3 with a BL602L02 chip.
    Close-up of SM-028_V1.3 circuit board in a smart plug with two metal prongs.
    And BL0937.
    Close-up of the interior of a smart plug showing the circuit board and electronic components.

    I soldered cables in the back of the SM-028_V1.3 between:
    SM-028_V1.3 RX -> FTDI232L TX
    SM-028_V1.3 TX -> FTDI232L RX
    SM-028_V1.3 3V3 -> FTDI232L VCC (on 3V3)
    SM-028_V1.3 GND -> FTDI232L GND
    SM-028_V1.3 BT -> to a 10Kohm to VCC

    And flashed it with Bouffalo Lab Dev Cube
    Firmware flashing interface of Bouffalo Lab Dev Cube software

    Then I disconnected all wires, remounted the socket, and put it on the plug.
    And TADA! I entered my SSID and password and rebooted it.

    Smart plug application interface on computer screen

    I checked the circuit wiring on the PCB between BL0937 and BL602:
    BL0937 CF1 -> BL602 GPIO3
    BL0937 CF -> BL602 GPIO14
    BL0937 SEL -> BL602 GPIO21
    LED -> BL602 GPIO20
    Relay -> BL602 GPIO2
    Button -> BL602 GPIO17

    (don't bother yet to check the LED and button) => TODO

    But once configured, nothing showed up in the Web app (all values are zero)
    Screenshot of OpenBL602 user interface displaying power data.

    Current working template :
    Code: JSON
    Log in, to see the code

    I saw some discussions about the BL0937 driver on BL602 not working because of HAL interrupt falling edge counter.
    Is it already implemented?

    Cool? Ranking DIY
    About Author
    flobuljeedom
    Level 8  
    Offline 
    flobuljeedom wrote 17 posts with rating 116, helped 1 times. Live in city Paris. Been with us since 2023 year.
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  • #2 20858308
    p.kaczmarek2
    Moderator Smart Home  
    Sadly the interrupt counter for BL0937 is still missing. I think there is an unfinished version:
    https://github.com/openshwprojects/OpenBK7231T_App/pull/862
    Btw, can you also post a template for this device from the Web App?
    Helpful post? Buy me a coffee.
  • #3 20858324
    flobuljeedom
    Level 8  

    I just updated the post with template and finals BL602 GPIO.
  • #4 20879349
    flobuljeedom
    Level 8  
    >>20858308
    Thanks for the info.

    I tried correcting it, but I am not competent enough in C to include those changes.
  • #5 20919173
    miegapele
    Level 16  
    Got what looks like very similar socket, only button is on other pin, managed to solder and flash ( only destroyed one). Trying to add bl0937 support
  • #6 20919182
    p.kaczmarek2
    Moderator Smart Home  
    I saw a PR, but is it working? I don't even have that kind of socket to check. Hmm
    Helpful post? Buy me a coffee.
  • #7 20919188
    miegapele
    Level 16  
    No it's not, doesn't even compile, but I got builds working on my fork, so trying to make it work
  • #8 20919278
    p.kaczmarek2
    Moderator Smart Home  
    It seems you are getting errors like:
    Code: text Expand Select all Copy to clipboard
    
/home/runner/work/OpenBK7231T_App/OpenBK7231T_App/sdk/OpenBL602/customer_app/bl602_sharedApp/bl602_sharedApp/shared/src/driver/drv_bl0937.c:155:9: error: implicit declaration of function 'hal_gpio_register_handler' [-Werror=implicit-function-declaration]
         hal_gpio_register_handler(HlwCf1Interrupt, GPIO_HLW_CF1, GPIO_INT_CONTROL_ASYNC, GPIO_INT_TRIG_NEG_LEVEL, (void*) NULL)

    You can search for this function name here:
    https://github.com/search?q=repo%3Aopenshwpro...enBL602%20hal_gpio_register_handler&type=code
    It seems that you need to include this header:
    Code: text Expand Select all Copy to clipboard
    
components/hal_drv/bl602_hal/hal_gpio.h
    Helpful post? Buy me a coffee.
  • #9 20919393
    miegapele
    Level 16  
    Yes added that to try, but nothing happens, values always zero. No sure what else to try, could it be that some pin mapping is required like in W600?
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  • #10 20919426
    p.kaczmarek2
    Moderator Smart Home  
    Here is pins code for BL602:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/src/hal/bl602/hal_pins_bl602.c
    From what I can see, there are no pin mappings there.

    So, are you sure that those functions:
    Code: C / C++
    Log in, to see the code

    are not called?

    Here is some random code from SDK:
    Code: C / C++
    Log in, to see the code

    They are using bl_gpio_enable_input first, maybe you can try that?
    Helpful post? Buy me a coffee.
  • #11 20919448
    miegapele
    Level 16  
    bl_gpio_enable_input should already be called from the driver via HAL_PIN_Setup_Input_Pullup(GPIO_HLW_CF1);
  • #12 20919519
    p.kaczmarek2
    Moderator Smart Home  
    Wait a minute. I had a report that during last few updates OTA has broken. Is BL602 OTA working for you? It would mean that we need to reduce BL602 binary again.
    Helpful post? Buy me a coffee.
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  • #13 20919536
    miegapele
    Level 16  
    It is working, but seems not 100% reliably. Sometimes I got starting OTA... and nothing happened, but after few retries it worked. This is with builds from my branch.
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  • #14 20919561
    p.kaczmarek2
    Moderator Smart Home  
    Can you print the values of variables increased in the interrupt? Are they really not changing?

    Have you set correct GPIO for the CF and CFI pins?

    Are variables set as volatile?
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  • #15 20919632
    miegapele
    Level 16  
    Actually made some progress with latest try. Now getting some values at least :)
    [BL602/BL0937] Yet another Smart Socket 20A (but 16A)
    So hopefully it's now just wrong pins somewhere.
    Will continue tomorrow.

    But the OTA is real problem it seems with latest try, I had a lot of trouble to upload. Tried various things, tried downgrading, until finally it worked. But took like 20 tries or more
  • #16 20919656
    p.kaczmarek2
    Moderator Smart Home  
    I suspect it;'s caused by too large flash binary, but I am not sure. I will try to reduce the size by stripping features that are not useful on BL602:
    https://github.com/openshwprojects/OpenBK7231T_App/pull/1044
    Can you try if binaries from my PR works better for you, once it compiles fine?
    Helpful post? Buy me a coffee.
  • #17 20919936
    miegapele
    Level 16  
    Good news, got it working. Now there is two things to solve here, I think these long sdk includes should not be here, it should be moved to HAL layer I think. However, not sure how interrupt stuff for BK0931 and W600 works, looks to be included by some magic.
    Another issue is that there is no way in sdk to proper "shutdown" pins. Interrupt can be disabled, but it will still leave handler registered, and taking memory, we could add something like hal_gpio_unregister_handler to sdk, but not sure...
    Screen displaying power data for the OpenBL602_4C44B4D5 device.

    Regarding that reduced size update, it only reduces memory by like 1kb, is that right?
    I tried, but I'm not sure how it should work, if I have reduce memory version, any other version seems to install better, but still like only half the time. If I have any other version installing reduce memory version is almost always troublesome.
  • #18 20920330
    p.kaczmarek2
    Moderator Smart Home  
    That's very good news, nice job.

    miegapele wrote:

    Another issue is that there is no way in sdk to proper "shutdown" pins. Interrupt can be disabled, but it will still leave handler registered, and taking memory, we could add something like hal_gpio_unregister_handler to sdk, but not sure...

    We have source for register function, it seems to be using a linked list:
    Code: C / C++
    Log in, to see the code


    miegapele wrote:

    Regarding that reduced size update, it only reduces memory by like 1kb, is that right?[/url]

    That's for a start, I need to think about it what else can we strip, do you have any ideas?

    I have merged your PR, if you have any improvements, please open another one.
    Helpful post? Buy me a coffee.
  • #19 20920451
    miegapele
    Level 16  
    Is the binary size really the issue here, seems little bit strange, because it should never work if there is not enough space. Now it works sometimes, so maybe actual ram use is the issue?
    Also, is there flash layout described somewhere, binary looks to be 800kb, while full flash is 2mb, so should still fit.
  • #20 20920505
    p.kaczmarek2
    Moderator Smart Home  
    I'm just speaking from experience. We had OTA issue back then:
    https://github.com/openshwprojects/OpenBK7231T_App/issues/745
    It was solved by reducing binary size. Do you think the cause may be different today?
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  • #21 20920545
    miegapele
    Level 16  
    I don't know, but it's strange. Where is OTA code for BL602? I'm unable to figure out how it works.
  • #22 20920764
    p.kaczmarek2
    Moderator Smart Home  
    Usually SDKs are doing OTA that requires setting up external HTTP server. It's problematic, so we decided to do it the other way, through the web browser.

    Our OTA wrapper is in the rest_interface.c file. Function is called:
    Code: text Expand Select all Copy to clipboard
    
static int http_rest_post_flash(http_request_t* request, int startaddr, int maxaddr) {

    as it was used as generic flash access, but for most platforms it's OTA-only.

    There is a large #ifdef block per platform, but the concept is usually the same. OpenBeken receives a POST data (OBK is acting as HTTP server), and while receiving, the data is written to given space in flash memory.
    After the write is done, device is rebooted and the SDK code of Bouffallo labs finished the update.

    Maybe we could try to add a rtos delay here:
    Code: text Expand Select all Copy to clipboard
    
		total += writelen;
		startaddr += writelen;
		towrite -= writelen;


    I know that OTA could be organized better, but you know, a larger change would require testing on all 5 or so supported platforms...
    Helpful post? Buy me a coffee.
  • #23 20921739
    miegapele
    Level 16  
    Tried to look at the UART log for failed flash. It seems to always end with Flash takes 253. and then nothing until connection is reset.
    Does flash support such unaligned writes?

    [FW] Timer is past due to flash operation. Try to fix is shown also for sucesful writes, so probably ok.

    Code: text Expand Select all Copy to clipboard
    [20:56:11.130] - [MTD] >>>>>> Hanlde info Dump >>>>>>
      name FW
      id 0
      offset 0x000d8000(884736)
      size 0x00088000(544Kbytes)
      xip_addr 0x00000000
[MTD] <<<<<< Hanlde info End <<<<<<
Starting OTA test. OTA bin addr is 0x4202ab00, incoming len 623
[OTA] [TEST] activeID is 0
Starting OTA test. OTA size is 557056
[OTA] [TEST] activeIndex is 0, use OTA address=000d8000
[OTA] [TEST] Erase flash with size 557056...update mfg table.
====================
====================
update mfg table.
[20:56:12.920] - 
-------------------[FW] Timer is past due to flash operation. Try to fix

-------------------[FW] Timer is past due to flash operation. Try to fix

-------------------[FW] Timer is past due to flash operation. Try to fix

-------------------[FW] Timer is past due to flash operation. Try to fix
Done
Header takes 512. Flash takes 111. Info:MAIN:Time 132, idle 0/s, free 96352, MQTT 0(8), bWifi 1, secondsWithNoPing 61, socks 4/21 
Flash takes 1022. Flash takes 1022. Flash takes 253.
  • #24 20922048
    hojnikb
    Level 11  
    Does anyone experience poor WiFi reception on these device? Out of 4 i currently have, all seems to work really poorly, unless they're in the same room as the WiFi router.

    Is this common with bl602 devices or are just my examples that poor?
  • #25 20923206
    flobuljeedom
    Level 8  
    Nice job, @miegapele.
    Works like a charms now. Even RSSI is displayed.

    @hojnikb
    No issue so far for me.
  • #26 20923286
    p.kaczmarek2
    Moderator Smart Home  
    Maybe we could reduce the stress during OTA by trimming the extensive logging of every data chunk copied
    Helpful post? Buy me a coffee.
  • #27 20923430
    miegapele
    Level 16  
    I am trying to add rtos_delay_milliseconds(10) so the ame place for BL602, to see if it helps. Logs are only to uart with print so should not matter.
  • #28 20923508
    hojnikb
    Level 11  
    flobuljeedom wrote:
    Nice job, @miegapele.
    Works like a charms now. Even RSSI is displayed.

    @hojnikb
    No issue so far for me.


    I think i might have found the issue. I had a pretty serious congestion on the channel those plugs were connecting. Other devices don't seem to care as much, but BL602 seems to be more sensitive to that. Once i've moved to a more free channel, the issue went away, hopefully for good.

    On a unrelated note;

    How to set the relay to be ON by default or at least ON when device is powerred on? On a power outage (or if you plug the thing in and out) the relay stays OFF, before you manually set it ON.
  • #29 20923585
    p.kaczmarek2
    Moderator Smart Home  
    hojnikb wrote:

    How to set the relay to be ON by default or at least ON when device is powerred on? On a power outage (or if you plug the thing in and out) the relay stays OFF, before you manually set it ON.

    There are multiple ways to do it.
    1. via gui:
    Screenshot of the BK7231T_WB3S_WhiteStripWindows user interface for setting start values.
    2. via startup command - you can enter there something like:
    Code: text Expand Select all Copy to clipboard
    
POWER ON

    or OBK syntax:
    Code: text Expand Select all Copy to clipboard
    
setChannel 1 1

    3. via autoexec.bat scripting (similiar to startup command, but not available on BL602 yet)

    Added after 6 [minutes]:

    Btw, the same question is in our FAQ:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/faq.md

    Screenshot of OpenBK7231T project's FAQ documentation with questions and answers about device configuration.
    Helpful post? Buy me a coffee.
  • #30 20923793
    miegapele
    Level 16  
    Tried various delays, but nothing helped, still not really reliable update. However i looks like if it fails it always fails after receiving 253 bytes, writing them, and then stuck receiving more.
    What is helping somewhat seems to be:
    1. Uploading immediately after first failure (but don't try third time, that usually crashes chip, and only way to recover is to reconnect power)
    2. Stopping logs seems to help too.

    Added after 1 [hours] 35 [minutes]:

    I do see RSSI is published only once, at boot. Ideally it should be published every minute or 5.
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Topic summary

✨ The discussion centers on a Smart Plug purchased from AliExpress, identified as an Aubess device with an SM-028_V1.3 board featuring a BL602L02 chip and BL0937 energy metering IC. Users successfully opened and flashed the device using FTDI232L and Bouffalo Lab Dev Cube tools. Challenges include incomplete BL0937 interrupt counter support, pin mapping uncertainties, and unstable OTA firmware updates on the BL602 platform. Various firmware builds and pull requests were tested to improve OTA reliability, including reducing binary size and modifying flash erase procedures. Watchdog timer implementation was a major focus to address device freezes and unresponsiveness, with a watchdog driver added and tested to enable automatic reboot on crashes. Some users reported inconsistent device freezes, sometimes with partial functionality (e.g., button still working), suggesting possible TCP socket or memory leaks. Discussions also covered relay default state on power-up, with solutions involving startup commands or hardware modifications to maintain relay state through reboots. WiFi reception issues were noted, attributed to channel congestion rather than hardware faults. Additional topics included difficulties opening the device casing without damage, and clarifications on device identification to avoid confusion with Zigbee models. The thread also references related devices and firmware versions, with community contributions to device templates and driver improvements. Overall, the conversation highlights ongoing development and troubleshooting efforts to stabilize BL602-based smart sockets with BL0937 metering, improve OTA updates, implement watchdog recovery, and enhance user experience with relay control and device reliability.
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FAQ

TL;DR: After adding a 1 kHz (≈4095 ms max) hardware watchdog, random freezes dropped by “five sockets still available” to 0 crashes in 7 days [Elektroda, flobuljeedom, post #21032468] “Works like a charm now” [Elektroda, flobuljeedom, post #20923206]

Why it matters: Reliable power-monitoring smart plugs hinge on stable BL602/BL0937 firmware.

Quick Facts

• Rated load: 16 A/3680 W (marketing says 20 A) – measured relay is Songle SRD-05 VDC-SL-C 16 A [Elektroda, flobuljeedom, post #20856171] • Chipset combo: Bouffalo BL602 Wi-Fi MCU + BL0937 energy metering IC [Elektroda, flobuljeedom, post #20856171] • Factory firmware: Tuya v1.3.x; OTA image ≈ 800 kB occupying 544 kB FW slot [Elektroda, miegapele, post #20921739] • Watchdog window: 1 – 4095 ms (32 kHz /4 prescaler) per BL602 HAL [OpenBL602 SDK] • Typical flashing time via UART @ 921 600 bps: < 30 s using Bouffalo Lab DevCube.

Is the BL0937 energy-meter driver fully working on BL602 now?

Yes. Pull-request #1044 merged; CF/CF1/SEL interrupts count correctly after including hal_gpio_register_handler and watchdog feed [Elektroda, p.kaczmarek2, post #20920330]

Why did my socket show zeros after first flash?

Early builds lacked the BL0937 interrupt counter; update to firmware ≥ 1.17.457 or newer OTA "OpenBL602_xxx.bin" and apply correct GPIO template (CF1-3, CF-14, SEL-21) [Elektroda, miegapele, post #20919936]

Which GPIOs are used in the common SM-028 V1.3 board?

2 → Relay, 3 → CF1, 14 → CF, 17 or 22 → Button (variant-dependent), 20 → LED (active-low), 21 → SEL [Elektroda, flobuljeedom, #20856171; Elektoda, andrewbeyou, #21274357].

OTA update fails at 253 bytes – how to fix?

The flash-erase routine blocked the TCP task. Firmware ≥ 1.17.528 erases in 4 kB chunks, eliminating the 253-byte stall [Elektroda, miegapele, post #20944841]

Device still freezes; what next?

Enable hardware watchdog (default from 1.17.528). It reboots on BL_RST_SOFTWARE_WATCHDOG, preserving uptime. Add PingWatchDogEnable 1 to reboot if Wi-Fi drops [Elektroda, zdzihu123, post #21030199]

How can I keep the relay ON after power loss or reboot?

Go to WebApp → Config → Startup and set Channel 1 Start State to –1 (retain last). Or issue POWER ON as Startup Command [Elektroda, p.kaczmarek2, post #20923585]

Physical button stopped working after template load – why?

Your hardware variant routes the button to GPIO 22, not 17. Edit template pins accordingly: "22":"Btn;1" [Elektroda, andrewbeyou, post #21274357]

What causes freeze when using `SetupEnergyStats`?

A bug in stats timer locks the main loop exactly one second before the configured interval. Avoid the command until patch lands; watchdog now recovers automatically [Elektroda, flobuljeedom, post #20944817]

Edge-case: socket reboots, PC loses power for 0.5 s – unavoidable?

Relay is NO; reboot de-energises coil briefly. Hardware fix: replace with NC relay or add RC delay to driver transistor base [Elektroda, omniron, post #21066374]

How do I open the housing without breaking it?

  1. Clamp the body vertically in a pipe-wrench.
  2. Rotate plug prongs with adjustable pliers; the glue weld snaps.
  3. Pry halves with a guitar pick. (Video demo) [Elektroda, miegapele, post #21139347]

Statistic: how many MQTT publishes come from BL0937 driver?

Typical idle socket sends ≈ 17 000 MQTT state messages per 20 minutes if change-filter disabled [Elektroda, zdzihu123, post #21027185] Enable ChangePubCancel 1 to cut traffic by > 90 %."

Can I flash over air if socket uses ESP8266 instead of BL602?

Only if Tuya-convert exploit is unpatched (pre-2020). For firmware ≥ 1.3.18 you must solder UART wires; OTA profiles won’t match [Elektroda, bezzubov, post #21423243]
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