Acaia Umbra Lunar BLE Protocol: Live Weight, Tare, Power, and Calibration Integration on iOS

[DarkWoke]

I’m developing a minimal iOS app to display live weight, tare, and ideally also power on/off and calibrate the Acaia Umbra Lunar scale. I’ve analyzed the Brewmaster and Artisan code, matched the UUIDs and command structure, and tried all known event/enable commands, but I only receive static weight values. I’d appreciate any guidance on the correct BLE sequence or protocol details, especially for power and calibration features.

1. BLE Protocol/Live Weight Streaming

• What is the exact sequence of BLE commands (including payloads and timing) required to enable live weight streaming from the Acaia Umbra Lunar scale?
• Is there a specific “event” or “enable notifications” command that must be sent to the scale after subscribing to the weight characteristic to receive live updates?
• Are there any required delays or handshakes between enabling notifications and sending commands to the scale?

2. Command Structure/Parsing

• Can you provide the correct structure and byte order for parsing the weight data from the 0x07 event? (e.g., which bytes represent the weight, factor, and sign, and are they big-endian or little-endian?)
• Are there any differences in the protocol or data format between the Umbra Lunar and other Acaia scales (e.g., Lunar, Pearl)?

3. BLE Characteristics/Descriptors

• Is it necessary to write directly to the CCCD (0x2902) descriptor on the Umbra Lunar, or is using setNotifyValue(true, for:) sufficient on iOS?
• Are there any additional characteristics or descriptors that must be written to (besides FE41 and FE42) to enable full functionality?

4. Tare/Command Issues

• What is the correct command and payload to send to the scale to trigger a tare operation?
• If writing to FE41 returns “Writing is not permitted,” what could be the cause, and how can it be resolved?

5. Power Control

• Is it possible to remotely turn the Acaia Umbra Lunar scale on or off via BLE from an iOS app? If so, what is the command sequence or characteristic to use?

6. Calibration Function

• How can we trigger the calibration mode (using the included 100g weight) via BLE? What is the correct command or procedure to start and complete calibration from an iOS app?

7. Troubleshooting/Best Practices

• Are there any known issues or quirks with the Umbra Lunar BLE implementation that differ from the documentation or other Acaia models?
• Do you have any sample BLE traffic logs (e.g., from nRF Connect or a sniffer) showing a successful session with live weight updates?

8. Open Source/Reference

• Is there any open-source code or documentation you recommend for correctly implementing the Umbra Lunar BLE protocol on iOS?
• Would you be willing to share a minimal working example (even in pseudocode) for connecting, enabling live weight, taring, power control, and calibration?

[MAKOMO]

This is the repository of the Artisan roast logging software. For any information on Acaia products please contact them directly.