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

patentjyp 17952 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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#61 21589619 25 Jun 2025 23:06

ausalex ausalex

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Post #61
21589619 25 Jun 2025 23:06

>>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 25 Jun 2025 23:15

p.kaczmarek2 p.kaczmarek2

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Post #62
21589630 25 Jun 2025 23:15

It seems to work on my iPhone. Can you provide more details which browser do you have?

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

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#63 21590483 26 Jun 2025 19:39

ausalex ausalex

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Post #63
21590483 26 Jun 2025 19:39

>>21589630

Safari on iOS 18.6 works now it is on my network but never worked when it was acting as a hotspot.
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#64 21590654 26 Jun 2025 21:58

p.kaczmarek2 p.kaczmarek2

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Post #64
21590654 26 Jun 2025 21:58

Hm.. let me recheck... in AP mode
iOS 15.8.3, it seems... still working

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

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#65 21629997 09 Aug 2025 11:34

bashioo bashioo

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Post #65
21629997 09 Aug 2025 11:34

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

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.
#66 21630790 10 Aug 2025 12:22

divadiow divadiow

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Post #66
21630790 10 Aug 2025 12:22

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.
#67 21702698 27 Sep 2025 22:31

mseelye mseelye

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Post #67
21702698 27 Sep 2025 22:31

>>21452814
@dullu
Hello, I have a very similar unit to the one you were able to flash.

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

✨ 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]

Is the pinout compatible with ESP-12 or TYWE3S boards?

Yes. VDD, GND, RST (CEN), TXD0 and RXD0 sit in the same positions; you can drop-in an ESP-12 if you add an external 10 kΩ pull-up to GPIO0 [Elektroda, p.kaczmarek2, post #20531756] – one user replaced it with an ESP32-C2 after adding that resistor [Elektroda, insmod, post #21483654]

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?

Solder a wire to the R2 pad (connected to GPIO8/BOOT).
Hold R2 at 3.3 V through a 10 kΩ resistor and power the board.
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]

Is there a status LED pin?

Yes. GPIO12 drives the Wi-Fi bicolour LED; set it as WifiLED 0 in OpenBeken templates [Elektroda, gyenchev, post #20533692]

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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