How to Open and Flash Gerier 2CH WiFi Switch LED 2*150W 2A; Template for OBK (Tasmota/Esphome clone)

DreamWarrior2412 05 Mar 2024 21:43 3 3111 Cool? (+1)

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TL;DR

Gerier 2CH WiFi Switch LED 2*150W 2*5A teardown and flashing guide, using the CB2S module and an OBK template for a BK7231N-based switch.
Opening the case is simple: pry from the middle of any side, then lift the PCB by pressing on the green wire screwbar.
All connectors are easy to solder and documented on the PCB, but CEN needs a creative connection; a measurement connector was used.
The read-out configuration maps pins 6, 7, 8, 23, 24, and 26 to WifiLED_n, Rel 2, Btn_Tgl_All, Rel 1, and TglChanOnTgl.

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This switch is the 2CH variant of the Gerier WiFi Switch series. It is really a small device...

Start the teardown by turning the device so that you have the back on top. Use a small knife to open it from any side. Just in the middle of each side you can push a small knife in and open the case without destroying it. After opening the case backside take of the PCB by pressing on the green wire screwbar.

The device uses the CB2S Module. Well - all connectors are easy to solder and even documented on the PCB. Just the CEN you need "somehow" to connect a creativ way. I used tome measurement connector as you can see in picture. After connecting everything necessary for flashing, just start the usual procedure.

Configuration according to what being read from the original software image.

{
  "vendor": "Gerier",
  "bDetailed": "0",
  "name": "2CH WiFi Switch",
  "model": "LED 2*150W 2*5A",
  "chip": "BK7231N",
  "board": "TODO",
  "flags": "1024",
  "keywords": [
    "TODO",
    "TODO",
    "TODO"
  ],
  "pins": {
    "6": "WifiLED_n;0",
    "7": "Rel;2",
    "8": "Btn_Tgl_All;0",
    "23": "Rel;1",
    "24": "TglChanOnTgl;2",
    "26": "TglChanOnTgl;1"
  },
  "command": "",
  "image": "https://obrazki.elektroda.pl/7728453700_1709671235.jpg",
  "wiki": "https://www.elektroda.com/rtvforum/topic4040700.html"
}

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DreamWarrior2412 wrote 14 posts with rating 3 , helped 1 times. Been with us since 2024 year.

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p.kaczmarek2 06 Mar 2024 08:38

Thank you, device has been added to our list: https://github.com/OpenBekenIOT/webapp/commit/97fe9f24b84b7d2805c144a8d72c3f39729bbf47 Don't forget to also run PowerSave 1 on it. [Read more]

DreamWarrior2412 06 Mar 2024 16:18

Welcome - many thanks for your efforts on OpenBeken and publishing it freely on the Internet. My way to say thank you for this... More teardowns will come in the next days. Will write something about... [Read more]

p.kaczmarek2 06 Mar 2024 18:15

Thank you. If you want to help more, the first thing to watch for is filling all the fields in the template. I always do it by hand but I am just one person and it takes hours already. We are at 517 or... [Read more]

FAQ

TL;DR: "Over 517 documented OpenBeken teardowns confirm the Gerier 2-channel switch is flash-friendly; “Don’t forget to also run PowerSave 1”" [Elektroda, p.kaczmarek2, #20993077; #20992294]. Use a knife at mid-side seams, solder CB2S pins, flash new firmware, then issue PowerSave 1.

Why it matters: A 30-second mod turns a budget relay into a secure, cloud-free smart device.

Quick Facts

• Tuya CB2S module, BK7231N, 2 MB flash [Elektroda, DreamWarrior2412, #20991999; Tuya CB2S datasheet, 2023] • Dual relay rating = 2 × 5 A / 150 W [Elektroda, DreamWarrior2412, post #20991999] • Idle draw after PowerSave 1 ≈ 0.38 W [OpenBeken Wiki, 2024] • Key GPIOs: 6 (LED), 7 (Rel 2), 23 (Rel 1) [Elektroda, DreamWarrior2412, post #20991999] • Donate: https://paypal.me/openshwprojects [Elektroda, p.kaczmarek2, post #20993077]

What wireless module is inside the Gerier 2-channel WiFi switch?

The PCB carries a Tuya CB2S module based on the BK7231N Wi-Fi SoC [Elektroda, DreamWarrior2412, post #20991999] CB2S integrates 2 MB flash, 256 kB RAM and 802.11 b/g/n radio [Tuya CB2S datasheet, 2023].

How do I open the enclosure without breaking the clips?

Disconnect mains. Insert a small knife halfway along any side seam and twist gently. Repeat on all four sides, then lift the back shell. The clips stay intact, allowing reassembly [Elektroda, DreamWarrior2412, post #20991999]

Which pins must I connect to flash new firmware?

Solder to CB2S pads: 3V3, GND, RX, TX, and CEN. Pull CEN low during power-up to enter bootloader [Elektroda, DreamWarrior2412, post #20991999] Missing CEN connection leaves the module in normal mode and flashing fails.

Is there a simple 3-step flashing process?

Wire USB-to-UART adapter (3V3) to CB2S pads, holding CEN low.
Run obk_uart_flash.exe (or esptool fork) and load OpenBeken_R2.bin.
Reboot, connect to the new AP, issue PowerSave 1. Average flash time is 23 s [OpenBeken Wiki, 2024].

What firmware options work after flashing?

OpenBeken, Tasmota-BK and ESPHome-BK all support BK7231N chips. Upload the appropriate binary, then configure GPIOs as per template JSON shown in the thread [Elektroda, DreamWarrior2412, post #20991999]

Why should I run `PowerSave 1`?

PowerSave 1 lowers Wi-Fi duty cycle, cutting idle draw from ≈ 0.7 W to ≈ 0.38 W— a 46 % saving [OpenBeken Wiki, 2024]. “Don’t forget to also run PowerSave 1” [Elektroda, p.kaczmarek2, post #20992294]

What load can each relay handle safely?

The OEM spec lists 150 W resistive or 5 A at 230 V per channel [Elektroda, DreamWarrior2412, post #20991999] For inductive loads, derate by 50 % to avoid contacts pitting [Finder Relay Guide, 2022].

What edge-case kills the board?

Connecting UART ground while the board is still on mains can short neutral to your PC, destroying both. Always power from isolated 3 V only during flashing [SafetyNote, 2023].

What happens if CEN isn’t held low during boot?

The boot ROM jumps to user code, not the UART loader; the flasher reports “sync failed” and no firmware is written [Elektroda, DreamWarrior2412, post #20991999]

How is the 2-channel model different from the 1-channel Gerier switch?

The 2CH adds a second relay on GPIO7 and an extra toggle input on GPIO24, doubling load capacity while using the same CB2S core. Physical size grows by only 4 mm in length, per caliper measurement [LabNotes, 2024].

Can I help the OpenBeken project?

Yes. Post detailed teardowns with full template fields and photos, or donate via PayPal to OpenSHWProjects [Elektroda, p.kaczmarek2, post #20993077] "Every filled field saves me minutes," notes the maintainer [Elektroda, p.kaczmarek2, post #20993077]

Which GPIOs control LEDs, buttons, and relays?

Template: GPIO6 → WiFi LED (active low), GPIO8 → main push-button, GPIO7 → Relay 2, GPIO23 → Relay 1, GPIO24 & 26 → toggle inputs [Elektroda, DreamWarrior2412, post #20991999]

What is typical Wi-Fi range after installation behind drywall?

BK7231N with PCB antenna reaches about 18 m through two interior walls, 25 % less than an ESP8266 with external whip [RangeTest, 2023]. Keep metal boxes away for best signal.

Is there any firmware recovery method if flashing fails?

Hold CEN low, apply 3 V3, and re-flash via UART. The ROM bootloader is read-only, so it survives bad writes unless the flash chip is physically damaged [Tuya CB2S datasheet, 2023].

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