[CBU/BK7231N] RTX QS-WIFI-S04-2C WRS2 Dual WiFi Repeater

Today we release from the cloud another product that is easy to buy in our country - a double RTX relay compatible with the Tuya application. As a standard, I will show its interior, describe the process of changing the firmware (where to solder the wires, etc.) and then I will give its configuration OpenBeken (which GPIO is the button, which is the LED, etc).

Product purchase
One of my readers bought the product on a Polish auction site, and I got it just to upload it to him OpenBeken
and then give back to the reader. Thank you! This is always a good opportunity to do a review and analysis.
The relay was quite expensive, all PLN 75, but such prices are often as we buy in our country:

Dimensions:

assembly diagram:

Specification:

And here I must already pay attention - unlimited range? No, it's just marketing. This device connects to our WiFi network and then the Tuya cloud actually allows you to control it from around the world, but it's different.
The annotation "works with mobile internet" is also interesting. Apparently, it is possible to pair this product with a hotspot and any WiFi, also mobile, ... but it does not change the fact that a WiFi router at home is needed to connect this type of Tuya products to the cloud.

Kit contents
Let's see what we get for these PLN 75.

This time it's poor... not even screws. The product also does not have "wings" for attaching, although there is this plastic hook.


Interior and firmware change
The white flap is on the hooks, just pry it with a screwdriver.

The system powers the KP15051SP, next to it you can see the AMS1117-3.3V LDO regulator.

The top of the PCB, in turn ... I have already described in the case of MOD003. It's identical here. Here is the analysis:

There is a module inside CBU, który znajduje się na dodatkowej płytce, na której też jest już jego przycisk (od parowania) oraz dioda LED od stanu WiFi.
Oto jego wyprowadzenia:


Just solder the wires to:
- RX
- TX
- 3.3V
- GND
Then you need to use Flasher:
https://github.com/openshwprojects/BK7231GUIFlashTool
As a rule, a photo from programming:

Note - performing a reboot by cutting off the power supply works only when we disconnect the whole thing from the computer with the USB to TTL programmer, and disconnect the 3.3V from the WiFi module. Then connect the USB to the computer, then start the programming/reading procedure in BK Flasher, and then connect the 3.3V pin. It will not work in any other order, nor will it catch if we just disconnect and connect 3.3V with the USB connected all the time. That is my observation.
You can also use the CEN reset method instead of power cycle, but I didn't want to solder another wire.
And configuration OpenBeken :
- P7 - WiFiLED_n
- P24 - TglChannelOnToggle - Channel 1
- P26 - TglChannelOnToggle - Channel 2
- P9 - Relay - Channel 1
- P17 - Relay - Channel 2
- P8 - Button - Channel 1 and Channel 2 (set two channels to control one by click and the other by double click)
Template:


Summary
This product is almost identical to the MOD003 from Modemix. The same child board from the CBU with additional pads to solder to the RX/TX. Programming went smoothly. Another device can run 100% locally.
As for the price, it's not very good. Sometimes it is possible to order a smart switch from China for half that amount, only then we wait much longer for the shipment. For the same amount, you can buy the whole "smart" switch instead of the flush module, which can also be more economical, depending on the intended use.
I hope someone may find this information useful. Meanwhile, there are more devices in the queue, LED strips, in which I will also change the batch for another person who does not feel up to the task of working with a soldering iron ...