[Bug]: brightness percentage math problem?

[deadlypantsd]

LocalTuya Version

2025.5.1

Home Assistant Version

2025.5.3

Environment

• Does the device work using the Home Assistant Tuya Cloud component?
• Is this device connected to another local integration, including Home Assistant and any other tools?
• The devices are within the same HA subnet, and they get discovered automatically when I add them

What happened?

Not quite sure how to put this...

I have 4 bulbs that are Merkury BW942s. 1% on the iOS app is brightness value of 25. 100% on the app is brightness value of 255. mushroom(?) card for light brightness says brightness value of 25 is 10%. Made sure that lower value is configured at 25 and upper value is 255. adjust brightness on iOS app to 10%, HA brightness percent says 18.

again - not sure how to word this.

percentage should be [(upper_val - lower_val) / 100]

is this the integration? or core HA issue?

Steps to reproduce.

1. add device.
2. adjust brightness with app / home assistant.

Relevant log output

not sure there is relevant info.

Diagnostics information.

No response

[xZetsubou]

How did you assume that your lower is 25 and max 255? most of tuya bulbs are lower 0 upper 1000 theses values ranges will be converted to 1-255 "0 is off" so when you change brightness from HA it will be converted to range 0-1000 but on HA will be converted to 1-255 range.

paste your device diagnostics

[deadlypantsd]

Not an assumption. Is it possible this is specific to this model lightbulb? On the Tuya Dev site (and raw data from HA) the brightness_value is 25 when the Tuya Smart app sets the bulb to 1%. Screenshots and diagnostics attached.

Snip from Tuya Dev console:

Device Info:

Device Status:

Snip from HA Dev Tools (States)

[deadlypantsd]

Screenshot from iOS App (iPhone)

[deadlypantsd]

Relevant data from diag:

    "device_config": {
      "device_id": "[redacted]",
      "dps_strings": [
        "1 ( value: True )",
        "2 ( value: 25 )"
      ],
      "enable_debug": false,
      "entities": [
        {
          "brightness": "2",
          "brightness_lower": 25,
          "brightness_upper": 255,
          "color_mode_set": "0",
          "color_temp_max_kelvin": 6500,
          "color_temp_min_kelvin": 2700,
          "color_temp_reverse": false,
          "entity_category": "config",
          "friendly_name": "jd_1",
          "icon": "",
          "id": "1",
          "music_mode": false,
          "platform": "light",
          "scene_values": {}
        }
      ],
      "friendly_name": "jd_1",
      "host": "[redacted]",
      "local_key": "[redacted]",
      "node_id": null,
      "protocol_version": "3.3"
    },
    "Discovered_Devices": null
  }

[xZetsubou]

Ok after further checks It's indeed there's an issue on the current logic it seems it doesn't works well I'll check, I'll re-open an issue for this.

[deadlypantsd]

No worries; thank you!! This integration is by far one of the best I've seen for Tuya devices!