Ampler eBike Bluetooth protocol
I have an Ampler Stout eBike which exposes metrics as Bluetooth attributes over GATT. I’d like to track the battery level and odomoter, so spent some time and decoded some of the attributes.
The bike exposes:
| Characteristic | Example data |
|---|---|
| 340d1528-a89e-4d4e-9078-06d21096ea36 | 0x5b 0x00 0x00 0x00 0x11 0x02 0x00 0x00 0x04 0x01 0x00 0x00 0x00 0x00 0x00 0x00 |
| 340d1529-a89e-4d4e-9078-06d21096ea36 | 0x00 0x00 0x00 0x00 0xdf 0x14 0x00 0x00 0x9c 0x0a 0x90 0x00 |
| 340d1530-a89e-4d4e-9078-06d21096ea36 | 0xa0 0x00 0x90 0x01 0x02 0x00 0x06 0x00 0x64 0x00 0xfa 0x00 |
| 340d1536-a89e-4d4e-9078-06d21096ea36 | 0x01 |
| 340d1538-a89e-4d4e-9078-06d21096ea36 | 0x00 |
| 340d1542-a89e-4d4e-9078-06d21096ea36 | 0x58 0x02 |
| 340d1544-a89e-4d4e-9078-06d21096ea36 | 0x00 |
| 340d1545-a89e-4d4e-9078-06d21096ea36 | 0x0a 0x18 0xe2 0x64 |
| 340d1547-a89e-4d4e-9078-06d21096ea36 | 0xff 0x02 0x11 0x00 0x00 0x00 0x03 0x00 |
| 340d1548-a89e-4d4e-9078-06d21096ea36 | 0x04 0x00 0x00 0x00 0x00 0x00 0x00 0x00 |
| 340d1549-a89e-4d4e-9078-06d21096ea36 | 0x00 0x00 0x00 0x00 |
| 340d1550-a89e-4d4e-9078-06d21096ea36 | 0x33 |
The format appears to pack related values into the same characteristic. Values are little endian and
either half words or words. The units seem to be metric such as m for range and m/s for speed
with a power of 10 multiplier, such as the voltage being in decivolts:
| Characteristic | Format | Fields |
|---|---|---|
| 340d1528-a89e-4d4e-9078-06d21096ea36 | HHhH | % charged, voltage (dV), temperature (dºC), ? |
| 340d1529-a89e-4d4e-9078-06d21096ea36 | III | ?, speed (mm/s), odometer (dm) |
| 340d1536-a89e-4d4e-9078-06d21096ea36 | B | assist level (0, 1, 2) |
| 340d1538-a89e-4d4e-9078-06d21096ea36 | ? (bool) | light |
| 340d1545-a89e-4d4e-9078-06d21096ea36 | I | ? increases over time 1692538885 |
The time value isn’t clear but might be a POSIX time, i.e. roughly Sunday, 20 August 2023.
Decoding the example above gives:
| Characteristic | Fields |
|---|---|
| 340d1528-a89e-4d4e-9078-06d21096ea36 | 91 % charged, 52.9 V, 26.0 ºC, 0 |
| 340d1529-a89e-4d4e-9078-06d21096ea36 | 0, 5343 mm/s (19.2 km/h), 943.9900 km |
| 340d1536-a89e-4d4e-9078-06d21096ea36 | assist level 1 |
| 340d1538-a89e-4d4e-9078-06d21096ea36 | light off |
Next step is to implement a decoder, export this to Home Assistant, and collect it via Prometheus.
