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

patentjyp 20514 66
Best answers LABEL_AI_GENERATED

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]
AI summary based on the discussion. May contain errors.
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  • #61 21589619
    ausalex
    Level 3  
    Posts: 5
    >>21589603

    Yes that is what appeared to be happening, in the browser window that appears on connect. It seems OK now it is connected to the network and I go there directly with Safari
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  • #62 21589630
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14767
    Help: 659
    Rate: 12907
    It seems to work on my iPhone. Can you provide more details which browser do you have?
    Info on BL602 Module SDV-002_V1.2 from Aliexpress 3-Gang Switch, Pin Compatibility & GPIOs
    Helpful post? Buy me a coffee.
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  • #63 21590483
    ausalex
    Level 3  
    Posts: 5
    >>21589630

    Safari on iOS 18.6 works now it is on my network but never worked when it was acting as a hotspot.
  • #64 21590654
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14767
    Help: 659
    Rate: 12907
    Hm.. let me recheck... in AP mode
    iOS 15.8.3, it seems... still working
    Info on BL602 Module SDV-002_V1.2 from Aliexpress 3-Gang Switch, Pin Compatibility & GPIOs
    Helpful post? Buy me a coffee.
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  • Flashed BL602 SDV-002_V1.2 relay module successfully

    #65 21629997
    bashioo
    Level 1  
    Posts: 1
    Thanks to this forum and this post specifically, I was able to flash yet another incarnation of a very similar relay from AliExpress.

    2 Channels eWeLink WiFi Smart Switch Module 7-32V

    AliExpress link: https://www.aliexpress.com/item/1005009212238503.html

    WiFi relay module SDV-002_V1.2 with two blue relays and various electronic components
    2CH eWeLink WiFi switch module placed on grey carpeted floor
    Smart switch box eWeLink 7–32V with WiFi, CE, and Alexa/Google Assistant logos
    Receiver module label with manufacturer details and CE, UKCA, RoHS markings
    WiFi relay module under magnifying glass, with soldered wires and a lit red LED

    Exactly the same BL602 Module SDV-002_V1.2.

    Flashed as per instructions from this post - powered the board separately via USB, and only connected Ground, TX and RX from FTDI adapter. Connected Reset to VCC via 10k resistor.

    Config:

    Code: text Expand Select all Copy to clipboard
    
{
  "vendor": "Tuya",
  "bDetailed": "0",
  "name": "Full Device Name Here",
  "model": "enter short model name here",
  "chip": "BL602",
  "board": "TODO",
  "flags": "1088",
  "keywords": [
    "TODO",
    "TODO",
    "TODO"
  ],
  "pins": {
    "0": "Rel;0",
    "1": "Rel;1",
    "12": "Btn;0",
    "22": "Btn;1"
  },
  "command": "",
  "image": "https://obrazki.elektroda.pl/YOUR_IMAGE.jpg",
  "wiki": "https://www.elektroda.com/rtvforum/topic_YOUR_TOPIC.html"
}


    Could not find WiFi LED though.
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  • #66 21630790
    divadiow
    Level 38  
    Posts: 5216
    Help: 448
    Rate: 917
    bashioo wrote:
    Could not find WiFi LED though.

    Odd. There can't be that many GPIOs left to try on that module when you subtract pwr, gnd and your other discoveries.

    Sometimes pin config is printed out at boot by factory firmware, if you took a backup.

  • Questions about boot mode wiring and pin mapping

    #67 21702698
    mseelye
    Level 1  
    Posts: 1
    >>21452814
    @dullu
    Hello, I have a very similar unit to the one you were able to flash.
    Relay board with Wi-Fi module and four push buttons on a green PCB

    Some QQs:
    Were you able to get it into boot mode using that R2 wire just going to Pin1/EN? Or did you find some other way to get to BT?

    Also I'm assuming in your images `Blue` is VCC, across from it `White` is GND, on the same side as GND is RX and TX (Red-ish and Tan-ish). And the other (white-ish) wire looks to be soldered to R2. Is that correct?

    Also, is TX actually connected to anything? I can't seem to trace it, (I have a SDV-002_V1.2 as well)

    Thank you!
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Topic summary

LABEL_AI_GENERATED
Discussion centers on identifying and flashing the BL602-based SDV-002_V1.2 module used in AliExpress 1/2/3/4-gang smart wall switches. The pinout was mapped by continuity testing and comparison with BL602/TYWE3S-style layouts: TX/RX, VCC/GND, relay control pins, button inputs, Wi‑Fi LED, and touch-chip connections were traced, while the BOOT function was confirmed via the BT/BT_EN pad and GPIO8/CHIP_EN-related wiring. Flashing was achieved using BLDevCube/blflash/OpenBK firmware, with boot mode entered by pulling the boot pad high through a resistor or wiring R2 to 3.3 V; several users reported handshake failures caused by weak USB-UART adapters or insufficient power. Final templates for OpenBeken/OpenBK were shared for 1-, 2-, 3-, and 4-gang variants, and the touch response delay was reduced using the “instant touch reaction” flag.
AI summary based on the discussion. May contain errors.
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FAQ LABEL_AI_GENERATED

TL;DR: For BL602 SDV-002_V1.2 switches with 1–4 gangs, “BOOT is GPIO8”: flash OpenBeken by using 3.3 V UART, RX/TX/GND, and the BT/R2 boot path; use verified GPIO templates to map relays, touch buttons, and Wi-Fi LED without cloud firmware. [#20533595] Why it matters: These low-cost eWeLink/AliExpress wall switches can run locally with OpenBeken, MQTT, and Home Assistant when flashed and powered correctly.

Option BL602 SDV-002_V1.2 support Home Assistant path Key limitation
OpenBeken Yes MQTT and Home Assistant discovery LittleFS disabled on BL602
ESPHome No BL602 support stated in thread Requires ESP module replacement Needs ESP strapping-pin care
Original eWeLink firmware Yes Cloud/app ecosystem Vendor cloud dependency

Key insight: The module is not an ESP module; it is a Trolink TI602B3S/SDV-002_V1.2 BL602 module. Treat BT/GPIO8 as the boot signal, not EN/CHIP_EN, and use a real 3.3 V supply.

Quick Facts

  • The SDV-002_V1.2 module was later identified as Trolink TI602B3S, using a BL602/BL602L20 family module in these switch boards. [#21125557]
  • Verified 3-gang OpenBeken mapping uses GPIO 1, 3, and 21 for relays; GPIO 2, 14, and 20 for buttons; GPIO 12 for Wi-Fi LED. [#20535155]
  • A 4-gang BL602L20 wall switch used GPIO 0, 2, 3, and 22 for relays, and GPIO 1, 14, 20, and 21 for buttons. [#21452814]
  • One PL2303 adapter board exposed only a 3.3 V LDO rated at 4 mA, which was insufficient for booting Wi-Fi reliably. [#20815848]
  • BL602 UART logs in the thread used 2,000,000 baud for one debug path and 115,200 baud for another UART path. [#20814624]

What is the SDV-002_V1.2 or TI602B3S BL602 module used in AliExpress eWeLink 1-gang, 2-gang, 3-gang, and 4-gang wall switches?

The SDV-002_V1.2 is a Trolink TI602B3S module based on Bouffalo Lab BL602/BL602L20. "BL602" is a Wi-Fi/Bluetooth microcontroller family that runs the switch logic, stores firmware, and exposes GPIO pins for relays, touch inputs, LEDs, UART, reset, and boot mode. It appears in eWeLink-compatible 1-gang, 2-gang, 3-gang, and 4-gang AliExpress wall switches. The thread also shows a 4-gang unit with Wi-Fi and 433 MHz support. [#21125557]

How do I identify the TX, RX, VCC, GND, EN, BT, and GPIO pins on an SDV-002_V1.2 BL602 module with a multimeter?

Use continuity mode to trace module pads to BL602 pins, relay transistors, touch chip lines, VCC, and GND. Compare the board pads against the known BL602 pinout and the TYWE3S-like footprint. TX and RX pads may exist on the module but be unconnected on the carrier PCB. EN maps to CHIP_EN, while BT maps to GPIO8 boot. Relay outputs usually trace through Q3, Q4, or Q5. Touch inputs trace toward the 10-pin touch controller. [#20531756]

How can I put the BL602 SDV-002_V1.2 module into UART boot/download mode without desoldering it from the switch PCB?

Pull the BT/GPIO8 boot path high during power-up; on tested boards, soldering to R2 and connecting it to 3.3 V worked. 1. Connect GND, TX, RX, and stable 3.3 V power. 2. Pull the R2 boot point to VCC during power-on. 3. Start BLDevCube or blflash, then remove the boot pull-up after flashing. One user confirmed that this R2 method entered boot mode without removing the module. [#20533595]

What is the correct OpenBeken pin configuration for SDV-002_V1.2 BL602 1-gang, 2-gang, and 3-gang touch wall switches?

Use the verified OpenBeken mappings from tested 1-gang and 2-gang units, with a later-tested 3-gang template. 1-gang: GPIO3 Rel, GPIO14 Btn, GPIO12 WifiLED. 2-gang: GPIO21 Rel0, GPIO20 Btn0, GPIO1 Rel1, GPIO2 Btn1, GPIO12 WifiLED. 3-gang: GPIO21 Rel0, GPIO20 Btn0, GPIO3 Rel1, GPIO14 Btn1, GPIO1 Rel2, GPIO2 Btn2, GPIO12 WifiLED. Channel order matters; wrong channels make one button switch another relay. [#20535155]

What OpenBeken template works for the 4-gang BL602L20 SDV-002_V1.2 eWeLink wall switch with four relays and four buttons?

Use GPIO0, GPIO2, GPIO3, and GPIO22 for relays, and GPIO1, GPIO14, GPIO20, and GPIO21 for buttons. The posted 4-gang template mapped GPIO0 Rel4, GPIO1 Btn4, GPIO2 Rel1, GPIO3 Rel3, GPIO14 Btn1, GPIO20 Btn3, GPIO21 Btn2, and GPIO22 Rel2. A later boot log from the original firmware also listed Wi-Fi LED as GPIO12. [#21454829]

Why does BLDevCube show BFLB IMG LOAD SHAKEHAND FAIL or BFLB LOAD HELP BIN FAIL when flashing a BL602 module?

The error usually means the flasher cannot complete UART boot handshaking with the BL602. Check three concrete causes first: BT/GPIO8 not held high at reset, RX/TX swapped or poorly soldered, and insufficient 3.3 V power. Then try a lower baud rate, shorter wires, or another USB-to-UART adapter. One user saw repeated “shake hand fail” and received the advice to test lower baud rates, swap RX/TX, and use another converter. [#21214638]

What power supply should I use when flashing BL602 modules, and why can cheap PL2303 USB-to-UART adapters cause boot or Wi-Fi failures?

Use a stable external 3.3 V supply or regulator, not the weak 3.3 V pin from cheap USB-to-UART adapters. One PL2303 board exposed only a 4 mA 3.3 V LDO, which cannot power a Wi-Fi module. The failure looked like successful flashing followed by no access point or repeated resets. A power bank or external regulator fixed the issue in the thread. [#20815848]

How do I flash OpenBeken to a BL602 SDV-002_V1.2 switch using BLDevCube on Windows or blflash on macOS/Linux?

Flash it through UART boot mode with BLDevCube on Windows or blflash on macOS/Linux. 1. Wire 3.3 V, GND, RX, TX, and pull BT/GPIO8 high during power-up. 2. In BLDevCube or blflash, select BL602 and the OpenBeken BL602 binary. 3. Flash, remove the boot pull-up, reset, then connect to the OpenBeken access point. One user flashed the devices on macOS using blflash after entering boot mode. [#20535290]

What is OpenBeken, and how does it integrate BL602-based eWeLink switches with Home Assistant and MQTT?

OpenBeken is custom firmware for Tuya-style and BL602 devices that provides local web configuration, MQTT, and Home Assistant integration. "MQTT" is a lightweight messaging protocol that lets the switch publish relay states and receive commands locally, avoiding the original cloud path. A 4-gang BL602L20 switch appeared instantly in Home Assistant after OpenBeken flashing and MQTT setup. [#21452814]

What is BLDevCube, and how is it used for flashing or backing up firmware on Bouffalo Lab BL602 devices?

BLDevCube is Bouffalo Lab’s Windows flashing utility for BL602 devices. "BLDevCube" is a vendor flash tool that loads a helper over UART boot mode, writes images to BL602 flash, verifies hashes, and can make backups in advanced mode. The thread mentions an older BlDevCube.exe inside the OpenBL602 SDK and recommends advanced mode for binary backup. [#20535243]

What is LittleFS, and why is it not enabled on BL602 builds of OpenBeken?

LittleFS is not enabled on BL602 OpenBeken builds because the chip has limited memory in this port. "LittleFS" is a small embedded flash file system that stores files such as scripts, web assets, or configuration data, but it needs firmware space and RAM. The recommended workaround is OpenBeken’s “Short startup command” instead of FileSystem tab scripts. [#20816125]

ESPHome vs OpenBeken for BL602 devices — which firmware option works for SDV-002_V1.2 modules and Home Assistant?

OpenBeken works on BL602 SDV-002_V1.2 modules; ESPHome support was stated as unavailable for BL602. A forum responder said, “ESPHome does not support BL602. OpenBeken is your only option.” For Home Assistant, use OpenBeken with MQTT or replace the module with an ESP-based module and then use ESPHome. The replacement route requires hardware changes, not just a firmware flash. [#21196987]

How can I reduce the 1–1.5 second touch response delay on OpenBeken BL602 touch wall switches?

Enable OpenBeken flag 6, the “instant touch reaction” flag. One user reported a 1–1.5 second delay on all touch switches after flashing. After setting flag number 6, the sensor response became instant. This is a software configuration fix, not a relay or touch-chip hardware modification. It applies when button events are delayed but GPIO mapping already works. [#20888453]

How do I fix OpenBeken Wi-Fi settings not saving from the device hotspot page on iPhone or iPad Safari?

Use a PC browser or open the OpenBeken page directly, because the iOS captive-portal view may hide the confirmation popup. One user on iOS 18.6 found the submit button darkened but settings did not save. The same device accepted Wi-Fi credentials from a PC, where the “Are you sure?” confirmation appeared. After joining the network, Safari worked when browsing directly to the device. [#21589553]

When replacing an SDV-002_V1.2 BL602 module with an ESP-12S or ESP32-C2 module, which strapping pins and pull-up resistors need to be considered?

Consider the ESP boot strapping pins, especially GPIO0 on ESP-12S. The module footprint can resemble ESP-12S, but boot requirements differ from BL602. One hardware replacement used an ESP32-C2 module with a 1 kΩ resistor. Another reply warned that the ESP-12S internal 10 kΩ pull-up on GPIO0 may not be enough, so an added pull-up may be required. [#21483654]
AI summary based on the discussion. May contain errors.
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