MiScale catty/jin units factor, and detecting catty on Mi Scale V2

[x11x]

The problem

Possibly incorrect conversion factor for Mi Scale V1

I was reading the code for Xiaomi MiScale and came across this https://github.com/esphome/esphome/blob/351ea045175c7f9fbd1afc3ff51cf1b61098a416/esphome/components/xiaomi_miscale/xiaomi_miscale.cpp#L98 For Chinese catty/jin units, it is multiplied by 0.6f. I thought it should be 0.5f. Is this possibly a typo in the code? I don't actually have a Mi Scale V1, I have Mi Body Composition Scale V2. And I don't actually use catty units. I have just been doing some research and noticed this while reading through your code. This issue probably needs to be confirmed by users who are actually using Mi Scale V1 with catty as unit, but I have seen elsewhere catty is 0.5 kg

EDIT: I have noticed on the Catty wikipedia page that in Korea and some other parts of Asia, a catty is 0.6 kg. So maybe the Korean models need the 0.6f conversion factor? Mine needed 0.5.

Not detected at all for Mi Scale V2

I have discovered that on Mi Body Composition Scale V2 (and probably Mi Scale V2 and others too), you can detect catty units by checking data[1] & (1 << 6) (6th bit of control byte counting from LSB as 0). Currently the xiaomi_miscale.cpp code is not detecting catty units at all for V2 scales, so this could be added. But as I said, I have only tested on my scale, and don't actually use catty units.

I have found other sources doing the same thing (6th bit of control byte 1):

• https://github.com/wiecosystem/Bluetooth/blob/master/doc/devices/huami.health.scale2.md#advertisement
• https://github.com/foormea/esp32_mi_scale_2/blob/master/esp_sketch/esp_sketch.ino#L283
• https://github.com/oliexdev/openScale/blob/83c2d941ea8ec349c92fba173398c97a5ee45b70/android_app/app/src/main/java/com/health/openscale/core/bluetooth/BluetoothMiScale2.java#L147
  • although there's an open bug report on this one as they are also using 6th bit as "isDateInvalid"

Which version of ESPHome has the issue?

2022.12.3 (and all prior)

What type of installation are you using?

Home Assistant Add-on

Which version of Home Assistant has the issue?

No response

What platform are you using?

ESP8266

Board

No response

Component causing the issue

xiaomi_miscale

Example YAML snippet

No response

Anything in the logs that might be useful for us?

No response

Additional information

No response

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