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[ESP8285] SE831L intelligent garage door controller - interior, analysis

p.kaczmarek2  13 3747 Cool? (+7)
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TL;DR

  • Analyzes the SE831L/GD-DC5 WiFi garage door controller sold as Sonoff eWelink, focusing on the ESP8285-based interior and firmware replacement path.
  • The PCB combines an ESP8285, an AMS1117-3.3V regulator, and a separate STC15W104 8051 MCU, while GPIO0 is wired to the button and RX/TX remain accessible.
  • The set cost about PLN 73 and takes 5V from USB, which is stepped down to 3.3V for the ESP8285.
  • Tasmota flashing works with esptool.py, and desoldering the extra MCU frees the ESP8285 GPIOs for custom Tasmota or Home Assistant use.
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I will present here a short analysis of the interior and the firmware change of the WiFi SE831L/GD-DC5 garage door controller advertised as Sonoff eWelink. As a standard, I will free it from the cloud, give the procedure for changing its firmware and configurations of its GPIO. This time the discussed driver will be based on ESP, so there will be a little change from what I usually show. I showed the driver based on BK7231 some time ago in the topic WiFi garage gate controller, Smart Garage Opener Tuya - Home Assistant , there I also provided an example YAML configuration for HA, I will not repeat it here.

Purchase of the ECN SN kit
The set was bought on a Polish auction site for about PLN 73:

Let's take a look at its description so you know what kind of product it is:

Assembly instructions:






Received set
Let's see what we get in practice:

Everything is there, there is an opening sensor, there is a cable to connect the button, there is a USB cable for power supply, and the manual and the device itself are also present.

How does such a controller even work?
I already described this in the previous topic about the gate, there was a controller on CB3S (BK7231N):
WiFi garage gate controller, Smart Garage Opener Tuya - Home Assistant

The inside of the controller
I skip the tests with the manufacturer's application, we immediately look inside. Just pry the cover up.


The ESP8285 is directly on the PCB here. There is also AMS1117-3.3V, because ESP requires 3.3V, and the input is 5V from USB. There is also a small SOIC8 chip inside, STC 15W104 H41U58 2241.XA. It is a microcontroller, core 8051.

Pinouts:

There is nothing interesting on the bottom of the PCB:



Based on the photos, I made a list of connections - it will also be useful for setting the Tasmota's GPIO:

Only that... if there is an additional MCU here, how can we set the GPIO? About that in a moment.

Firmware change
You can easily upload Tasmota here. RX and TX is available. The UART port is not occupied by the MCU, it is not a TuyaMCU device. This microcontroller is on a regular GPIO.
GPIO0 is on the button, just press it before connecting the power.


esptool.py works, as I have already described several times:
https://www.elektroda.pl/rtvforum/topic3866386.html
The only thing left is what about the MCU...
My suggestion is to desolder it. First, we apply flux, then additional lead binder (we make bridges on its pins), and then we quickly heat both sides with a soldering iron. The layout can be removed after a while with tweezers:

And that's it for now. Then it is enough to make jumpers and program the Tasmot IO, but more on that another time.

Summary
Changing the firmware turned out to be very simple. At first I was worried about GPIO0, but it turned out that this signal is brought out to the button, so there was no problem with putting the ESP into programming mode. I also had concerns about this mysterious MCU, but it turned out that you can desolder it and just freely use the ESP8285 IO and script it as we like in Tasmot / Home Assistant.
I will try to show the configuration of the sensor itself, connecting it to the gate and a practical presentation soon, in a separate topic.
Does any of the readers have such "intelligent" (whatever it means - this is the language of advertisers) garage doors controlled by WiFi? There are no problems with the WiFi range Before gate? Maybe I'm just too skeptical. I invite you to the discussion.

About Author
p.kaczmarek2
p.kaczmarek2 wrote 14394 posts with rating 12315 , helped 650 times. Been with us since 2014 year.

Comments

tmf 02 Jul 2023 12:17

So, I'm curious about two things. The first - sense. According to the descriptions, it is connected to the gate drive. Generally, probably all drives come with a receiver and remote controls. So what... [Read more]

p.kaczmarek2 02 Jul 2023 13:13

I don't know if I'm the right person to answer the first question, because I'm interested in these gadgets from a technological point of view, and at home I mainly have "dumb switches" (read:... [Read more]

tmf 02 Jul 2023 14:51

Thanks for the info. I actually think the same about it. I am not talking about the general benefits of home automation, but about this particular device. As you wrote, originally it is strongly related... [Read more]

ArturAVS 02 Jul 2023 18:12

After all, the situation is almost identical with other devices, e.g. CCTV IP cameras. Unfortunately, people wanting to make their lives easier forget about their own privacy. [Read more]

krzbor 02 Jul 2023 23:22

What was that MCU 8051 there for? ESP will easily handle the reed switch and relay. [Read more]

p.kaczmarek2 03 Jul 2023 06:04

@tmf I am against all kinds of subscriptions, even those for VOD services, although at the same time I see (even from family members) that some people wouldn't manage without them. A much bigger problem... [Read more]

William Bonawentura 03 Jul 2023 06:20

Does the manufacturer warn in the manual about the legal risk of installation? The motorized gate is not a toy and must comply with the requirements of the Machinery Directive. As long as it was controlled... [Read more]

noel200 06 Jul 2023 09:59

I attached a small magnet to the gate, and next to the gate I screwed a yunshan plate with a reed switch at the entrance. I have in the app whether the gate is closed. Unfortunately, I often forget "did... [Read more]

metalMANiu 06 Jul 2023 14:31

I have 2 garage doors with an electric drive and control with a 433MHz remote control. Half a year I couldn't find time to connect some "Smart" switch to it. Once I found the time and sat down, I... [Read more]

borba 08 Jul 2023 19:08

I have the exact (or very similar) model. And it's been working for a year now. Because the backyard garage is built of concrete walls about 15 cm thick, unfortunately, it was necessary to add a... [Read more]

metalMANiu 09 Jul 2023 07:52

@borba and isn't this Ewelink based on Tuya? [Read more]

borba 09 Jul 2023 07:56

I don't know anything about it. From what I've read (I'm just an amateur, that's why I haven't uploaded my own software to the WiFi controllers that I have with 9 at home yet), eWelink... [Read more]

Perelka 06 Apr 2025 11:13

Hi I have been a user of a number of Sonoff units around the house for several years. Mainly the Mini R2 but also three of the same as in the subject for the gates in the garages and the entrance gate.... [Read more]

FAQ

TL;DR: PLN 73 (~€16) kit, “Changing the firmware turned out to be very simple” [Elektroda, p.kaczmarek2, post #20638623], needs <10 min to flash Tasmota locally and cut the cloud link. Users then gain offline gate control and stronger privacy.

Why it matters: Swapping two wires and one file turns a cheap cloud-bound device into a secure, local opener.

Quick Facts

• MCU combo: ESP8285 (1 MB flash) + STC15W104 8051 [Elektroda, p.kaczmarek2, post #20638623] • Power: 5 V USB input → AMS1117-3.3 V regulator [Elektroda, p.kaczmarek2, post #20638623] • Retail price: PLN 73–85 in 2023 [Elektroda, p.kaczmarek2, post #20638623] • Relay rating: Typical 10 A / 250 VAC (Songle SRD series datasheet) • esptool.py write time: ≈2 min for 512 KB image (Tasmota Docs)

What hardware is inside the SE831L garage door controller?

The PCB holds an ESP8285 Wi-Fi SoC, an STC15W104 8-bit 8051 MCU, an AMS1117-3.3 V regulator, one Songle relay and a reed-sensor input header [Elektroda, p.kaczmarek2, post #20638623]

How do I enter flashing mode on the ESP8285?

Hold the front button (wired to GPIO0) while powering by 3.3 V; the chip boots into UART bootloader. Connect RX, TX and GND to a 3.3 V USB-TTL adapter [Elektroda, p.kaczmarek2, post #20638623]

Can you outline the flashing steps?

  1. Solder header to RX, TX, 3.3 V, GND.
  2. Press the front button and plug USB-TTL power.
  3. Run esptool.py write_flash 0x0 tasmota.bin. Total time ≈2 min [Tasmota Docs].

Which GPIO pins do I map in Tasmota?

GPIO5 → relay, GPIO4 → reed sensor, GPIO0 → button, GPIO14 → optional wall-switch. The removed STC MCU frees these pins for direct use [Elektroda, p.kaczmarek2, post #20638623]

Why is there an extra 8051 MCU and can I remove it?

Vendors add a companion MCU for Tuya-style serial protocols or cheap input debouncing. It is not required for standalone ESP control. Desoldering with flux and braid takes seconds and simplifies GPIO mapping [Elektroda, p.kaczmarek2, post #20638623]

Does eWeLink rely on the Tuya cloud?

No. eWeLink uses Sonoff’s AWS-hosted servers, while Tuya devices talk to Tuya’s own cloud. Both, however, keep command paths outside your LAN [Elektroda, borba, post #20647195]

What security risks exist if I keep the stock firmware?

Original firmware stores SSID and Wi-Fi keys unencrypted; they can be dumped via UART [Elektroda, p.kaczmarek2, post #20638838] Remote servers may expose unpatched APIs. A 2020 study found 53 % of IoT images leak credentials [Hernandez, 2020].

Will the gate work if my internet drops after flashing Tasmota?

Yes. Tasmota responds to LAN MQTT/HTTP commands and to the local button even with zero connectivity [Tasmota Docs].

Are there legal requirements for remote-controlled garage doors?

EU Machinery Directive 2006/42/EC demands the operator must monitor movement or add safety edges/photocells. Remote internet control may shift liability if no visual confirmation exists [Directive 2006/42/EC].

How can I improve Wi-Fi range through 15 cm concrete walls?

Place a repeater within line-of-sight of the opener. One user restored stable links for 10 months after adding a repeater [Elektroda, borba, post #20646858]

Edge case: firmware 3.6.0 stops the gate after a few centimetres—fix?

Bug appears when Sonoff re-triggers on contact sensor change. Downgrade to 3.5.x or flash Tasmota; both remove the double-pulse issue [Elektroda, Perelka, post #21508733]

What does the mod cost versus a DIY ESP relay?

SE831L costs ≈€16; a bare ESP01S, relay board and case cost €8–10. The mod saves assembly time but not money [Elektroda, p.kaczmarek2, post #20638623]

How do I secure Tasmota after flashing?

Set a strong Web UI password, disable MQTT auto-discovery, block WAN ports and enable SetOption19 0. Follow the five-step checklist in the official Tasmota hardening guide [Tasmota Docs].
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