The Thump GO is visible as two Bluethooth devices. Thump GO is an audio device. The Bluetooth device named LE_Thump GO is used for controlling the loudspeaker.
Only after an audio connection was established and the bluetooth LED lights solidly, the LE_Thump GO device is active. (With Auto Connect off, connect from a previously paired audio device to reach that state. With Auto Connect on, this state is only reached 60 seconds after turning on, even if the audio connection is established much earlier, but one can presses the PAIR button to shorten that time.)
The Bluetooth device LE_Thump GO is the interface the official app Thump Connect 2 uses. This device offers service UUID 49535343-fe7d-4ae5-8fa9-9fafd205e455. Appearently, this is the BM70/RN4870 chip with service "Microchip Transparent UART". Here, I list all the commands of the device I could reverse-engineer. I assume no liability for the correctness. All numbers are in hexadecimal notation.
| ID | Function | Values |
|---|---|---|
| 01 | Front LED | 00 (off) or 01 (on) |
| (02) | Battery SOC | ff (?), ..., f1, ee, ... 77, 73, 70 = LED green (100% to 20%) 6c, 69, 65, 62, 5e, 5b, 57 = LED yellow (20% to 5%) 54, ... = LED red (less than 5%) |
| 03 | 01 | |
| 04 | Auto Link | 00 (off) or 01 (on) |
| 05 | Auto Connect BT | 00 (off) or 01 (on) |
| 06 | 00 | |
| 07 | 00 | |
| 08 | Main Volume | ff (full volume) to 00 ff=-0dB, fe=-0.5dB, fd=-1dB, ..., ea=-10dB |
| 09 | Main Mute | 00 (unmuted) or 01 (muted) |
| 0a | Voicing Mode | 00 (Music) 01 (Speech) 02 (Monitor) 03 (Sub) |
| 0b | Outdoor Mode | 00 (off) or 01 (on) |
| 0c | Music Ducking | 00 (off) or 01 (on) |
| 0d | Feedback Eliminator | 00 (off) or 01 (on) |
| 0e | Custom EQ low | fa (-6 dB) to ff (-1 dB), 00, 01 (+ 1 dB) to 06 (+6 dB) |
| 0f | Custom EQ high | fa (-6 dB) to ff (-1 dB), 00, 01 (+ 1 dB) to 06 (+6 dB) |
| 10 | 00 | |
| 11 | CH1 Volume | ff (full volume) to 00 ff=-0dB, fe=-0.5dB, fd=-1dB, ..., ea=-10dB |
| 12 | CH1 Mute | 00 (unmuted) or 01 (muted) |
| 13 | 00 | |
| 14 | CH2 Volume | ff (full volume) to 00 ff=-0dB, fe=-0.5dB, fd=-1dB, ..., ea=-10dB |
| 15 | CH2 Mute | 00 (unmuted) or 01 (muted) |
| 16 | 00 | |
| 17 | 00 | |
| 18 | 15 | |
| 19 | 00 |
All the push-button actions (I mean the physical push buttons on the device) can be executed via the Bluetooth protocoll, except the Bluetooth button.
The physical dials (for gain and Main volume) cannot be operated via Bluetooth. 100% on the Bluetooth protocol corresponds to the respective physical dial. The volume can only be lowered(or muted completely) via Bluetooth.
Linked Mode settings (for connecting two loudspeakers) could not be tested.
Write at characteristic 49535343-8841-43f4-a8d4-ecbe34729bb3.
Write bed103XXYYef, with XX=ID and YY=Value.
Example: bed1030a01ef sets voicing mode to Speech.
Listen to notifications of characteristic 49535343-1e4d-4bd9-ba61-23c647249616.
Every 600 milliseconds, a notification indicating (virtual) signal level LEDs is sent. (These level LEDs are not present on the device, but in the virtual mixer of the app.) This is message bed506XX00YY00ZZ00ef with XX=Main, YY=CH1, ZZ=CH2 – with values 00 (LED off) or ff (LED on = signal on this channel).
Every 6 seconds, the battery state of charge (SOC) is transmitted. bed50302XXef with XX being the SOC. Values as described in the Settings Vector table.
Write the command bed104ef to get the settings vector, in 2 parts.
Response 1: bed505010eXXXXXXXXXXXXXXXXXXXXXXXXXXXXef, with the payload being the settings vector with IDs 01 through 0e.
Response 2: bed5050f09XXXXXXXXXXXXXXXXXXXXXXef, with the payload being the settings vector with IDs 0f through 19.
If a setting is changed via button press on the device, this is announced with a bed503XXYYef notification, with XX=ID and YY=Value.
Example: bed5030b01ef Outdoor Mode on
Writing bed112ef to bed115ef results in consistent answers (some consistent per session, some across sessions). These could include product ID, serial number, session IDs.
Command bed10aef starts link mode, command bed10bef ends it.
Status changes are announced (bed5030601ef on, bed5030600ef off) for both, Bluethooth command and button press on the device.
Not owning a second Thump GO loadspeaker, link mode could not be tested.