Voltage calibration in openbeken CB2S/BK7231N/BL0937 - how to perform?

Welcome.
I have just started playing with IoT, I bought two WiFi sockets with energy metering. One of them I reflashed on openbeken 1.17.419.
The socket uses the CB2S/BK7231N and BL0937 module (as far as I can trust what the flasher reads from the original Tuya firmware).
Everything works fine - turns on/off, connects to the network and mqtt.
However, the energy measurement readings differ from what the socket not yet flashed shows.
The flashed socket shows 250V, the original 232.8V. Is there any method to calibrate this firmware.

.

There are two ways to perform energy measurement calibration in OpenBeken:
1. You can use the commands VoltageSet , PowerSet , CurrentSet , whose names and syntax are the same as in Tasmot. We calibrate analogously to Tasmota.
Here you have a list of commands:
https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/commands.md
2. You can use a GUI overlay downloaded from Github, i.e. open Web App and under Tools 2. Tools is Calibration :
Basically in the paragraph Calibration it is written in English what to do. This overlay uses the aforementioned commands anyway VoltageSet and so on, simply packs them into the HTML form


For real measurements (current, voltage, power) for the VoltageSet/PowerSet/CurrentSet commands you can at least use a second unflashed socket you have or some other meter. I recommend using a classic 60W tungsten bulb as a test load.

I have a problem with VoltageSet, CurrentSet in 1.18.62 running on TOMPD-63WIFI:

Error:CMD:cmd VoltageSet NOT found (args 235)
Info:CMD:[WebApp Cmd 'VoltageSet 235' Result] Unknown command

Error:CMD:cmd CurrentSet NOT found (args 0.323)
Info:CMD:[WebApp Cmd 'CurrentSet 0.323' Result] Unknown command

These commands are only available for the devices that you calibrate, i.e. devices with BL0947, BL0937, etc. If you have a device using TuyaMCU, the calibration option is not available, as in this case it is the MCU (additional microcontroller) that handles the energy measurement and reports to the WiFi module the already finished numerical values.

Calibration in firmware is available because when you change the firmware of the WiFi module you lose the factory calibration, but this is only true for devices with BL0947/BL0937. For devices with TuyaMCU, we do not lose the factory calibration.