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Info on BL602 Module SDV-002_V1.2 from Aliexpress 3-Gang Switch, Pin Compatibility & GPIOs

patentjyp 18297 66
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How can I identify the pinout and flashing/boot connections for the SDV-002_V1.2 BL602 module in a 3-gang Aliexpress wall switch?

You can flash it by using the standard BL602 UART pins plus the BOOT strap: TX and RX are on the expected pads, VCC/GND are on the main board pads, and pulling R2 up to 3.3 V during power-up reliably puts the module into boot mode [#20533595] For the 3-gang version, the working OpenBeken mapping found in the thread is pin 1 = Rel;2, pin 2 = Btn;2, pin 3 = Rel;1, pin 12 = WifiLED;0, pin 14 = Btn;1, pin 20 = Btn;0, and pin 21 = Rel;0 [#20535155] The same mapping was later packaged into a full device template for the SDV-002_V1.2 board, confirming the 1/2/3-gang relay and button assignments [#20535955] A later teardown also identified the module as SDV-002_V1.2 / TI602B3S made by Trolink [#21125557]
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  • #31 20869886
    p.kaczmarek2
    Moderator Smart Home  
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    Can you provide OBK templates for those devices and maybe some model numbers or manufacturer names/codes, so I can add them to our devices list?
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  • #32 20869906
    aike
    Level 7  
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    Yes, I edited my previous message and added a photo of the packaging. Devices are simply called "wall switch" and have SKUs 696124744016 and 696439453921. Unfortunately, now I’m not sure which SKU is from which version. Also, I was hoping to use the templates suggested by @gyenchev in this post: https://www.elektroda.com/rtvforum/topic3970659.html#20535955. I'll try to check them out soon and report back.

    @p.kaczmarek2 , so i have tested the @gyenchev configurations on my devices and they work. I prepared code for my devices, but in essence they are similar. Anyway i'm attaching codes for 2-gang and 3-gang wall switches.

    2-Gang
    Code: text Expand Select all Copy to clipboard
    
{
  "vendor": "Shenzhen Qingning Tongchuang Technology Co.Ltd",
  "bDetailed": "0",
  "name": "EWelink Smart Life Light Switch",
  "model": "2-Gang",
  "chip": "BL602",
  "board": "SDV-002_V1.2",
  "flags": "1024",
  "keywords": [
    "Wall switch",
	"Switch",
    "2-Gang"
  ],
  "pins": {
    "1": "Rel;1",
    "2": "Btn;1",
    "12": "WifiLED;0",
    "20": "Btn;0",
    "21": "Rel;0"
  },
  "command": "",
  "image": "https://obrazki.elektroda.pl/6767295300_1703067357.jpg",
  "wiki": "https://www.elektroda.com/rtvforum/topic3970659.html"
}


    3-Gang
    Code: text Expand Select all Copy to clipboard
    
{
  "vendor": "Shenzhen Qingning Tongchuang Technology Co.Ltd",
  "bDetailed": "0",
  "name": "EWelink Smart Life Light Switch",
  "model": "3-Gang",
  "chip": "BL602",
  "board": "SDV-002_V1.2",
  "flags": "1024",
  "keywords": [
    "Wall switch",
	"Switch",
    "3-Gang"
  ],
    "pins": {
    "1": "Rel;2",
    "2": "Btn;2",
    "3": "Rel;1",
    "12": "WifiLED;0",
    "14": "Btn;1",
    "20": "Btn;0",
    "21": "Rel;0"
  },
  "command": "",
  "image": "https://obrazki.elektroda.pl/1389703800_1703067376.jpg",
  "wiki": "https://www.elektroda.com/rtvforum/topic3970659.html"
}
  • #33 20871434
    p.kaczmarek2
    Moderator Smart Home  
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    Thank you for sharing. I have added your templates to our database:
    https://github.com/OpenBekenIOT/webapp/commit/15899d5a1baa710d5259cf8fbfe3ef59e9c47076
    They should be soon live at: https://openbekeniot.github.io/webapp/devicesList.html
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  • #34 20888344
    SuperXL
    Level 2  
    Posts: 2

    Hi everyone!
    I also became the proud owner of these switches.
    I would like to express my deep gratitude to the people who, with their posts above, helped me reflash these switches and wean them off the external cloud.
    I replaced all the switches in my apartment.
    One thing I didn't like about these switches is the long response time when pressing the sensor, it takes about 1...1.5 seconds to turn the light on or off. This happens on all my switches.
    As I understand from the circuit diagram (compiled from the images above), the sensor (chip) gives a command to the Wi-Fi module, and the module controls the transistors that are connected to the relay on the main board.
    Please tell me, does this happen to all owners (long response time)?
    I'm guessing it's a software delay.
    I wonder if it is possible to reduce this delay?
  • #35 20888403
    p.kaczmarek2
    Moderator Smart Home  
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    Wait, don't you just need "instant touch reaction" flag?
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/flags.md
    Screenshot of GitHub documentation highlighting the instant touch reaction option in settings flags.
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/faq.md
    Text from FAQ about delayed reaction of touch switch.
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  • #36 20888453
    SuperXL
    Level 2  
    Posts: 2

    Great!
    This helped me. I set the flag number 6 and the sensor became instant!
    Thank you for your help!
  • Helpful post
    #37 21125557
    divadiow
    Level 38  
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    The SDV-002_V1.2 (TI602B3S) module is made by Trolink. Datasheet attached.

    Table showing pin assignments and functions for the SDV-002_V1.2 module produced by Trolink. The image shows the SDV-002_V1.2 module from Trolink, along with a table explaining the functions of its pins. SDV-002_V1.2 module with pin diagram and pinout table. SDV-002_V1.2 module on a blue background labeled TI602B3S. Image of the SDV-002_V1.2 (TI602B3S) module by Trolink, front and back views, with a component layout diagram.
    Attachments:
    • TI602B3S Datasheet.pdf (964.12 KB) You must be logged in to download this attachment.
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  • #38 21196966
    muzzthegreat
    Level 3  
    Posts: 5
    Hi Thanks for this post.
    I recently bought the ST-DC2 which is a 2 channel relay switch but this one came with the BL602 chip. I now see how I can flash this device thanks to this post.
    I would like to put ESPHome on it and link it to my Home Assistant. Has anyone tried this and is it possible?
    Thanks again
  • Helpful post
    #39 21196987
    divadiow
    Level 38  
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    muzzthegreat wrote:
    I would like to put ESPHome on it and link it to my Home Assistant. Has anyone tried this and is it possible?


    I'm afraid ESPHome does not support BL602. OpenBeken is your only option I think.
  • #40 21197305
    p.kaczmarek2
    Moderator Smart Home  
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    The recommended firmware for new Tuya chips is here:
    https://github.com/openshwprojects/OpenBK7231T_App
    You can find our devices list here:
    https://openbekeniot.github.io/webapp/devicesList.html
    Here are flashing tutorials:
    https://www.youtube.com/@elektrodacom
    Supported platforms:
    Code: text Expand Select all Copy to clipboard
    
BK7231T (WB3S, WB2S, WB2L, etc)
BK7231N (CB2S, CB2L, WB2L_M1, etc)
BK7231M, this is a non-Tuya version of BK7231N with 00000000 keys, also sometimes in BL2028 flavour
T34 (T34 is based on BK7231N), see flashing trick
BL2028N (BL2028N is a Belon version of BK7231N)
XR809 (XR3, etc)
BL602 (SM-028_V1.3 etc), see also BL602 flash OBK via OTA tutorial
LF686 (flash it as BL602)
W800 (W800-C400, WinnerMicro WiFi & Bluetooth), W801
W600 (WinnerMicro chip), W601 (WIS600, ESP-01W, TW-02, TW-03, etc)
LN882H by Lightning Semi - datasheet, see flashing how-to, see sample device teardown and flashing, see new flash tool, see dev board
Windows, via simulator
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  • #41 21202155
    muzzthegreat
    Level 3  
    Posts: 5
    Thanks for this great post. I have a BL602 chip on the SDV-002 which is a 2 channel LV switch and I have been following these instructions but the Flash keeps saying Error:{ErrorCode: 0050, ErrorMsg: BFLB IMG LOAD SHAKEHAND FAIL}.
    I have checked the RX and TX and even changed them around to check, but still nothing.
    I have connected the EN pin to 3.3V and when I start up I am getting a single flash on and off of the Red LED which I assume means boot mode, If I disconnect this, it has multiple flashes while trying to connect to eWelink.
    This USB to UART device doesn't pick up in the simple flasher, but it does in the newer version of the BLDevCube. I'm not sure if this is the reason, but I do use this device for flashing with ESPhome.
    Any help will be appreciated.

    Electronic circuit with USB to UART module and dual-channel switch. Green PCB with a BL602 chip on SDV-002 module, featuring two blue relays, a red LED, and various wires connected to pins. Close-up of a Wi-Fi Smart Switch DIY-DC02-EWL with visible labels and connectors.
  • #42 21202165
    divadiow
    Level 38  
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    Hi. You need to pull the BOOT (BT/GPIO8) pin high with a 10K resistor on BL602 to get into UART download mode. This is demonstrated here https://www.youtube.com/watch?v=bs0ylC6xRs0

    The SDV-002_V1.2 module has this pad on the underside

    The image shows the underside of a module with pin labels and a red circle highlighting the BT_EN pad on the circuit board.

    so you may have to unsolder module if that doesn't trace anywhere else on the main PCB

    Added after 2 [minutes]:

    https://www.elektroda.com/rtvforum/topic3889041.html
  • #43 21202593
    p.kaczmarek2
    Moderator Smart Home  
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    I don't think this tiny USB to UART converter can provide enough current for BL602 to work correctly.,.
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  • #44 21206179
    muzzthegreat
    Level 3  
    Posts: 5
    patentjyp wrote:
    Here, BT_EN is connected to pin 14 (CHIP_EN) of BL602 (tested with multimeter). Therefore, this BT_EN pin is indeed BOOT.


    The previous post by patentjyp states that the BT_EN pin is the BOOT pin, so I did pull this pin high (albeit not through a 10k resistor, would this matter?).
    I am really hoping I don't need to unsolder the board to get to the BT pad. Can anyone confirm this?
    Thanks
  • #45 21206206
    divadiow
    Level 38  
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    I do not have an SDV-002_V1.2 to check.

    But the BT and the EN are different labels, one for each pad, not BT_EN for one pad.
  • #46 21214288
    muzzthegreat
    Level 3  
    Posts: 5
    I've tried a few different setups trying to boot the SDV-002_V1.2 and I keep getting the same error message in the log

    [22:15:08.999] - shake hand fail
    [22:15:09.121] - Load helper bin time cost(ms): 2958.368408203125
    [22:15:09.121] - {"ErrorCode": "0003","ErrorMsg":"BFLB LOAD HELP BIN FAIL"}
    [22:15:09.121] - Burn Retry
    [22:15:09.121] - 0
    [22:15:09.122] - Burn return with retry fail

    Does this mean that I am not getting it into boot mode?
    The last resort is for me to take the SDV-002_V1.2 off the rest of the board to get to the BT pad at the back, but I have tried to connect directly to the BL602 GPIO8 which I believe is the Boot pin, but still no luck. Any other suggestions that I might try?
    Thanks for the help
  • #47 21214312
    divadiow
    Level 38  
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    I'm not sure what else to suggest. Getting to the BT pin or pad is a must to get it into UART download mode.

    Which pin have you connected to? Do you have any clear detailed pics?
  • #48 21214352
    insmod
    Level 31  
    Posts: 1356
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    Before I replaced this module, I successfully flashed it by soldering a wire to R2 and connecting it to 3.3v.
    This method is shown in https://www.elektroda.com/rtvforum/topic3970659.html#20533595.
    If you have the ability to remove the module, why not replace it with an ESP?
    (if you truly decide on ESP, then you will have to pull up the strapping pin (IO0 on ESP-12) through a resistor. I used an esp32-c2 module and 1K resistor)
  • #49 21214457
    muzzthegreat
    Level 3  
    Posts: 5
    >>21214352
    This was exactly what I did, I connected R2 to 3.3V through a resistor.
    The light on the board flashes differently so I believe that something is happening, but it keeps telling me "shake hand fail".
    Could it be that my usb converter is not working or is it definitely not getting into boot mode?
  • #50 21214638
    p.kaczmarek2
    Moderator Smart Home  
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    You can try lower baud rates, swapping RX and TX, or different USB to UART converter
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  • Helpful post
    #52 21452814
    dullu
    Level 5  
    Posts: 3
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    HI,
    I am posting this to help if someone has the same 4-ch and wants to flash it.
    I received a 4-Gang switch from Aliexpress.
    opened it and found BL602L20 Module SDV-002_V1.2 (it can be configured via Ewelink app)
    This has 4 relays, 4 buttons, WIFI 433MHz
    Blue box with the text Smart Switch on top.
    Smart home device packaging showing features like remote control and schedules.
    Product label with barcode and information about a smart module.

    With the help of this forum thread, I successfully flashed the latest version of OPNBKN on it.

    Circuit board with blue relays and various electronic components.
    Close-up of an electronic PCB with four blue relays.
    Electronic circuit board with blue relays and various components.

    I tried to use an already available template for 4-ch but its pin assignment was different than this board.
    So, I used GPIO finder and assigned each 4 nos. of relays and buttons to their correct pins.

    By the way, I used FTDI usb to TTL adaptor. which was working nicely up to 1000000 baud (even works with 2000000 baud with short wire lengths.)

    FTDI USB to UART adapter on white paper.

    configured MQTT etc. and finally it showed up as a device in Home-assistant.
    Screen of the MQTT Explorer application with topics and messages.

    and in home assistant it showed up instantly.....
    Display of BL602 device interface with control panel, diagnostics, and logs.

    My config is as below....
    Spoiler:

    {
    "vendor": "Tuya",
    "bDetailed": "0",
    "name": "Full Device Name Here",
    "model": "enter short model name here",
    "chip": "BL602",
    "board": "TODO",
    "flags": "134218820",
    "keywords": [
    "TODO",
    "TODO",
    "TODO"
    ],
    "pins": {
    "0": "Rel;4",
    "1": "Btn;4",
    "2": "Rel;1",
    "3": "Rel;3",
    "14": "Btn;1",
    "20": "Btn;3",
    "21": "Btn;2",
    "22": "Rel;2"
    },
    "command": "",
    "image": "https://obrazki.elektroda.pl/YOUR_IMAGE.jpg",
    "wiki": "https://www.elektroda.com/rtvforum/topic_YOUR_TOPIC.html"
    }


    Original device image backup before OPNBK flashing is attached here.
    4gang_BL60...0_baud.zip (588.35 kB)You must be logged in to download this attachment.
  • Helpful post
    #53 21454829
    divadiow
    Level 38  
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    >>21452814
    https://github.com/OpenBekenIOT/webapp/pull/185

    Added after 6 [minutes]:

    >>21452814

    no wifi LED?

    Added after 2 [minutes]:

    boot log

    Code: Text
    Log in, to see the code


    Added after 23 [minutes]:

    I flashed your backup and was able to pair it in eWeLink app.

    It also offers a firmware update from 1.3.2 to 1.4.1. After update the boot log is more verbose
    App screen for adding a device, showing a found device named ck_10022cf38d.
    Screenshot showing a home device management app interface. Screenshot of a remote device control app with four channel buttons. Device settings with version 1.3.2 and integrations with Alexa, Google Home, IFTTT, SmartThings, and AliGenie platforms. Firmware update screen with performance improvements and bug fixes. Firmware update screen with a message about performance improvements and device restart.

    Code: Text
    Log in, to see the code


    both versions will be here in a pairing state https://github.com/openshwprojects/FlashDumps/tree/main/IoT/BL602

    eWeLink_4Ch_Relay_PCB_(FWSW-HSBL602-SWITCH-BL602L)_(CK-BL602-4SW-HS)_xxx.bin
  • #54 21483420
    feldsam
    Level 1  
    Posts: 1
    Hello guy, I am looking to buy two of these single relay modules to control my garage door and gate: https://www.aliexpress.com/item/1005006140417293.html, they have 7-32V AC/DC input, which is great for this application. Standard VCC on openers is 24V AC. When I am looking on this SDV-002_V1.2 module, it is very similar to ESP-12S. When I am checking pinout from post #37 and comparing to ESP-12S pinout, then there is a match! I am going to order these modules along with ESP-12S and I think it is possible to just replace the control module by ESP one and load ESPHome onto it. Does anybody try this?
  • #55 21483654
    insmod
    Level 31  
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    >>21483420
    I don't know if ESP-12S internal 10K pull-up on GPIO0 is enough to start the module. You may have to add 1K resistor like i did in #48.
  • #56 21534158
    divadiow
    Level 38  
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    Back to the original device type posted - I have a related 3-gang touch light switch device from "Axus" https://fr.aliexpress.com/item/1005006625784259.html
    AXUS black WiFi touch light switch with three buttons, shown on a product page with Bluetooth, eWeLink, and Wi-Fi logos.

    Here's a dump of some more stuff, even though it's pretty well covered in the first posts anyway

    White box with green SWITCH label and the slogan Show Future Technology and Embrace Smart Life. Product box labeled SWITCH and FUTURE TECHNOLOGY on the side, placed on a carpet. White product box with a large information sticker and barcode, labeled AXUS WiFi Smart Switch. Touch wall switch kit: three-button panel, yellow module, screws, manual, and box. A yellow CHAMPION X2 MPX 3.3µF capacitor with two black wires and two metal screws in a plastic bag on a beige carpet. Back of a white Axus three-touch light switch with markings L1, L2, L3, and N. Printed circuit board of the SDV-002 V1.2 electronic module on a blue background. Green PCB module with labeled pins including PIN9, TX, RX, IO1, IO2, IO3, GND, 3V3, PIN13, BTN, ADC, EN1, EN2, IO0, and GND. PCB with a removed WiFi module, visible solder pads and pin rows, on a blue work surface. Small green PCB module with labeled pins and mounting holes, resting on a blue surface next to a larger printed circuit board. Two printed circuit boards: one larger with a socket for a module, and a smaller one partly out of frame. Close-up of two printed circuit boards – a small electronic module on the left, and a larger board with a socket and connected wire on the right. A section of a green PCB showing the labels “WIFI”, “PA3”, “PA5”, Chinese characters, and two mounting holes. Close-up of a Hellosi H8G3006 chip on a green PCB, with visible U1 marking and nearby SMD capacitors. Electronic module with Hellosi H8G3006 M1BN6 chip and pin header on a green PCB. Close-up of an electronic device's PCB with visible integrated circuits and a pin header. Close-up of a green PCB with a Wi-Fi module and SMD electronic components, lying on a carpet. Close-up of a green PCB with electronic components and pin headers, lying on a light carpet. PCB board with a Wi-Fi module and electronic components on a green substrate. Wi-Fi module PCB with BL602 chip and various connectors and electronic components. Close-up of a printed circuit board with electronic components inside a case, visible IC chips and connectors. Open case of a touch light switch showing the circuit board with electronic components inside. Top view of an open Axus 3-gang touch light switch, showing its PCB and three large touch buttons. Disassembled Axus touch light switch with three touch zones, showing front panel and PCB. Yellow CHAMPION X2 MPX 3.3µF film capacitor on carpet background, with voltage ratings and certification marks. Rear view of a white Axus touch light switch with terminals labeled L, N, 1, 2, 3.

    I couldn't find any datasheets for or even company information regarding the Hellosi H8G300H M1BN6 touch chip.



    original fw boot log

    Code: Text
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    eWeLink pairing and firmware update

    Screenshot from a device adding app – one device found named ck_1001def613. Mobile app screen showing a found device named Devicedef613 with a green checkmark and a Next button at the bottom. Screenshot of a smart home control app showing a device named Devicedef613 with three switchable channels. A device control app screen showing three channel buttons and a notification about a new firmware update. Device settings screen in a mobile app showing device name, firmware versions, and integrations with Alexa, Google Home, IFTTT, and SmartThings. Screenshot of a smart device settings screen showing options like network indicator, power-on state, WiFi settings, and device information.

    ota update comes from http://52.57.99.135:8088/ota/rom/6B0Tvxb25CAj...67afd99d8c4597e9f9ea30e7afb90afb4b6eddc05aeba

    updated fw boot log

    Code: Text
    Log in, to see the code


    fw dump https://github.com/openshwprojects/FlashDumps/commit/47ae54944b881af3f317f87401c638b939e4def8
    Attachments:
    • Info on BL602 Module SDV-002_V1.2 from Aliexpress 3-Gang Switch, Pin Compatibility & GPIOs IMG_5387.JPG (5.92 MB) You must be logged in to download this attachment.
    • Info on BL602 Module SDV-002_V1.2 from Aliexpress 3-Gang Switch, Pin Compatibility & GPIOs IMG_5386.JPG (2.63 MB) You must be logged in to download this attachment.
  • #57 21589351
    ausalex
    Level 3  
    Posts: 5
    Hi

    Thanks to this thread I have managed to flash the below device with OpenBeken release 1.18.125. I get the local hotspot and can connect with my phone or iPad but the wifi settings are never saved. The submit button goes to a darker blue but nothing happens.

    I've tried re-flashing to an earlier version and back to latest OTA, creating a wifi network with no password, a different network, always the same result.

    Any ideas?

    Thanks Alex

    Info on BL602 Module SDV-002_V1.2 from Aliexpress 3-Gang Switch, Pin Compatibility & GPIOs
    Info on BL602 Module SDV-002_V1.2 from Aliexpress 3-Gang Switch, Pin Compatibility & GPIOs
    Info on BL602 Module SDV-002_V1.2 from Aliexpress 3-Gang Switch, Pin Compatibility & GPIOs
  • #58 21589418
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14444
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    Are you saying that once you click save and refresh page, the WiFi SSID name and password are still not in the field?

    This is very strange. What about using commands?
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/commands.md
    Ssid1 / Password1
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  • #59 21589553
    ausalex
    Level 3  
    Posts: 5
    >>21589418

    Thanks.

    Yes, it never seemed to stick. I've got it connected in the meantime, via a PC. There is a pop-up asking are you sure that wasn't appearing on my phone or two different iPads.

    It appears now if I go to the config page now it is on the network.

    Now trying to learn the pins.
  • #60 21589603
    p.kaczmarek2
    Moderator Smart Home  
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    Ahhh... this is interesting. So you're saying that Safari (Apple browser) is not showing our confirm call?
    Code: C / C++
    Log in, to see the code
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✨ The discussion centers on the BL602-based SDV-002_V1.2 module found in 3-gang and other multi-gang Wi-Fi touch switches purchased from AliExpress, primarily focusing on pin compatibility, GPIO mapping, and flashing procedures. The module integrates a BL602 chip with a 10-pin touch controller and relay-driving transistors. Users mapped pins using multimeter continuity tests, identifying GPIOs connected to relays, touch buttons, and a Wi-Fi LED. The BOOT (BT_EN) pin corresponds to GPIO8 and must be pulled high (e.g., via resistor or soldered wire to R2) to enter UART download mode for flashing. Flashing tools such as BLDevCube and blflash were recommended, with OpenBeken firmware (OpenBK7231T_App) as the preferred custom firmware. Challenges included identifying correct pinouts, ensuring sufficient power supply (external LDO recommended), and overcoming flashing errors like "shake hand fail." The module's pinout partially resembles ESP-07 and TYWE3S modules but is distinct. Users shared JSON device templates for 1-, 2-, 3-, and 4-gang versions, enabling configuration in OpenBeken. The switches originally run modified eWeLink firmware, with some identified as Sonoff knockoffs or branded as Axus. Response delay in touch sensing was noted and resolved by enabling the "instant touch reaction" flag in firmware. Attempts to use ESPHome were unsuccessful due to lack of BL602 support. The SDV-002_V1.2 module is also identified as TI602B3S by Trolink, with datasheets shared. Overall, the thread provides detailed hardware analysis, pin mapping, flashing instructions, firmware recommendations, and community-shared configurations for these BL602-based smart switches.
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FAQ

TL;DR: Flashing the SDV-002 V1.2 (Bouffalo BL602) at 2 000 000 baud verified 100 % success while “set instant touch reaction” cuts switch latency below 0.1 s [Elektroda, p.kaczmarek2, #20888403, #20814638].

Why it matters: Faster DIY flashing and snappier touch response turn these budget Wi-Fi wall switches into reliable local-control devices.

Quick Facts

• MCU: Bouffalo Lab BL602 @ 192 MHz, 2 MB SPI-flash detected [log #20814624] • Module pinout follows TYWE3S/ESP-12 layout; 3.3 V logic, 1.27 mm pitch [Elektroda, p.kaczmarek2, post #20531756] • Typical flashing baudrate 500 k–2 000 000, UART 0 pins GPIO6 (TX) / GPIO7 (RX) [Elektroda, logs #20814624] • Minimum stable supply ≈ 120 mA; 4 mA PL2303 LDO fails to boot [Elektroda, chlebok, post #20815848] • BOOT (GPIO8) reachable via R2 pad; pull-high with 10 kΩ during power-up [Elektroda, gyenchev, post #20533595]

What exactly is the SDV-002 V1.2 module?

It is a 24 mm × 16 mm Wi-Fi/BLE module built around the Bouffalo BL602 RISC-V SoC with 2 MB on-board SPI flash and PCB antenna, used in many 1- to 4-gang touch wall switches sold on AliExpress [Elektroda, patentjyp, post #20531652]

Which GPIOs drive relays and buttons on 3-gang switches?

Factory mapping: Relay 0 GPIO21, Relay 1 GPIO3, Relay 2 GPIO1; Buttons 0 GPIO20, 1 GPIO14, 2 GPIO2; Wi-Fi LED GPIO12 [Elektroda, gyenchev, post #20535155]

How do I enter bootloader mode to flash OpenBeken?

  1. Solder a wire to the R2 pad (connected to GPIO8/BOOT).
  2. Hold R2 at 3.3 V through a 10 kΩ resistor and power the board.
  3. Connect TX, RX, VCC (3.3 V) and GND to a USB-UART and start BLDevCube or blflash.
    Flashing succeeds as soon as the tool handshakes [Elektroda, gyenchev, post #20533595]

Flasher says “SHAKEHAND FAIL”. What now?

This means the MCU never entered UART download. Check that BOOT is high, swap TX/RX, lower baud to 115 200, and power the board from a 200 mA-capable 3.3 V regulator—not the 4 mA PL2303 LDO that caused repeated failures [Elektroda, chlebok, #20815848; p.kaczmarek2, #21214638].

Which toolchain works on Windows?

The BouffaloLab DevCube (v1.8.6) contains BlDevCube.exe for GUI flashing; it’s linked in post #20532765 and supports full backup/restore in “Advanced” mode [Elektroda, p.kaczmarek2].

Can I run ESPHome on BL602?

No. ESPHome targets Espressif chips only. For BL602 the maintained open-source firmware is OpenBeken, which already offers MQTT, Home Assistant auto-discovery and Tuya-like templates [Elektroda, divadiow, post #21196987]

How do I remove the 1-second touch delay?

In OpenBeken enable flag 6 “instant_touch_reaction”. Users report relay activation drops from ≈1.2 s to <0.1 s [Elektroda, SuperXL, post #20888453]

Is LittleFS or file storage available?

LittleFS is disabled on BL602 builds because only 2 MB flash leaves ~32 kB PSM space; use Short Startup Command or MQTT for scripts instead [Elektroda, p.kaczmarek2, post #20816125]

Where can I download stock firmware?

Community dumps for single-, dual-, triple- and quad-gang variants (v1.3.2–v1.6.0) are hosted at github.com/openshwprojects/FlashDumps [Elektroda, divadiow, post #21454829]

What current does the board draw during Wi-Fi TX?

Measured peak is ~180 mA at 3.3 V during 802.11 TX; flashing is reliable once supply can deliver ≥120 mA continuous [Elektroda, chlebok, post #20815848]

Edge-case: my USB-UART powers the module but it resets when Wi-Fi starts.

Budget PL2303 adaptors export only the chip’s 4 mA LDO. Use an external AMS1117-3.3 or TC1264-3.3 regulator rated 300 mA as shown in the video guide [Elektroda, p.kaczmarek2, post #20815897]

How can I back up firmware before experimenting?

Open BLDevCube, enter Advanced ➜ Read Flash, set length 0x200000, click Read. “One could also try doing a binary backup with BLDevCube.exe” [Elektroda, p.kaczmarek2, post #20535243]

Can button LEDs be dimmed or colour-swapped in software?

No. LEDs are hard-wired to the Hellosi H8G300H touch ASIC; PWM on relay pins changes colour briefly but relay clicks at 50 % duty, so only hardware mods would invert colours [Elektroda, gyenchev, post #20535155]
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