Configuring EARU EAWCBT WiFi Relay with OpenBK on BK7231N Chip

EARU Wifi Relay model EAWCBT support.

Hi guys,

I recently bought on Aliexpress some cheap WiFi Relay, and wanted to use OpenBK on it.

This model is not yet in device database, but I managed to make it working with openBK.

This is the device :

I quickly opened it up, by drilling on existing rivets. They can be replaced with some screws later.

Inside, it is a CBS3 chip (BK7231N) with a relay activated by a bridge.



I use this datasheet to find correct pinout : CB3S datasheet and BK7231 GUI Flash tool to flash it.

Here is the correct pins to use when updating device:


It worked flawlessly


Then I connected to device using onboard AP, and configured it to use my wifi.
On next reboot, I used the suggested configurations by the BK7231 Flash Tool, but it doesn't work. Relay was seen as a relay, not a bridge driven relay.

After some testing, here is the configuration that works for me.



Hope it helps!

Thank you for sharing. It's good to see another bridge relay device. Out of curiosity, have you tried to measure the power consumption of this device? The bridge relay requires only power to toggle, so it should be more efficient than "classic" relay, where coil in one state has to be energized all the time.

By the way, I think you can also enable PowerSave 1 on this device. This will prolong the life of the power supply and reduce heating.

Hi p.kaczmarek2 ,

Thank you for your message, it helps!

First of all, I tried measuring consumption, and then I read your comment about PowerSave, it changed everything!

	Consumption	Relay activation
Normal	7mA	28mA
PowerSave 1	1.3mA	8.7mA

1.3mA, this is excellent! Day consumption is (0.0013x230)*24 = 7.2 Watt!

I was amazed it can change consumption like this!

I also noticed that my whole relay setting was inverted. When I got Power OFF, I got power, and vice versa.
I modified the config (and updated my first post) to make it match reality.
By now, when I issue a POWER OFF command, JSON output match.

Hi all,

A quick update on this Earu relays.

They work fine.

I did update today to latest 1.18.141 firmware. Works perfectly.

I also sorted out a strange behavior. If relay was ON when rebooting, device says OFF but relay was still ON. Need to cycle power button to fix it.

I just set default value (-1) for both Channel 0 and Channel 1 and it did the trick (in Config menu, then Configure Startup).
And I understood my error. As it is a bridge, it uses 2 channels (0 and 1) to change bridge state. Then it needs to know both values to restore correct state on a reboot.

Hi all,
I want to develop an application to read the power measurements and save it in a database from an EARU EAWCBT Wi-Fi.
Could you give me some information about it?

You mean after flashing with OBK?

Use obk HTTP API.

>>21777226

Hi,

Power measurement is not available on this particular relay model.

For other model, such as Earu EAKCB-T-M, reading is available with HTTP GET.
I use it with RedNode to read wattage value.

This is an example of device answer with command: cm?cmnd=STATUS





You can see voltage, frequency, power, ...

But only for relay with metering function available.

Hope this helps

Ah yes, I apologize, I assumed that @eguivigo is asking for measurement access on the device that has it. Well, if your device does not feature power measurement, then there is no way to access it, obviously. First please double check in the product listing or within Tuya app, just to be sure. Then proceed to flashing.

You can also use SendGET command with $voltage or $power or $current arguments (if your device has measurements). That way OBK can send data to HTTP server which you can later process in PHP.