Major refactoring to address memory efficiency, advertisement cycling,
and immediate advertising support:
**Use FixedVector instead of std::vector:**
- Replace std::vector with FixedVector for measurements storage
- Initialize with exact sizes determined from configuration
- Eliminates STL reallocation overhead and reduces flash usage
- Uses runtime-sized FixedVector allocated once in setup()
**Config key changes:**
- Use `sensors` and `binary_sensors` (plurals) for consistency
- Matches ESPHome conventions for sensor arrays
**Advertisement size management and cycling:**
- Calculate max advertisement size (31 bytes total, minus overhead)
- Split measurements across multiple packets if they don't fit
- Automatically cycle through packets on each advertising interval
- Ensures all sensors get advertised even with many measurements
- Overhead: 8 bytes unencrypted, 16 bytes encrypted
**Immediate advertising support:**
- Add `advertise_immediately` option for sensors/binary_sensors
- When enabled, triggers immediate advertisement on state change
- Interrupts normal advertising cycle to send only that sensor
- Resumes normal cycle after immediate advertisement
- Perfect for motion sensors, door sensors, or critical alerts
**Implementation details:**
- Refactored encode functions to use raw pointers and calculate sizes
- Build multiple advertisement packets as needed
- Track current packet index for cycling
- Handle immediate advertising with separate packet building path
- Proper encryption handling with per-packet counters
Example configuration:
```yaml
bthome:
sensors:
- type: temperature
id: room_temp
- type: humidity
id: room_humidity
binary_sensors:
- type: motion
id: pir_sensor
advertise_immediately: true # Instant notification
- type: door
id: front_door
advertise_immediately: true
```
Implements native BTHome v2 protocol support for broadcasting sensor data
over BLE advertisements. This enables ESP32 devices to act as battery-powered
BLE sensors that are natively compatible with Home Assistant.
Features:
- Support for multiple sensor types (temperature, humidity, battery, etc.)
- Support for binary sensors (motion, door, window, etc.)
- AES-CCM encryption support with 16-byte keys
- Automatic packet encoding per BTHome v2 specification
- Dynamic advertisement updates when sensor values change
- Configurable advertising intervals and TX power
- Proper BTHome v2 device info byte and service UUID
Implementation:
- Python configuration for sensor/binary sensor mapping
- C++ component for BTHome packet encoding and BLE advertising
- mbedtls CCM encryption for secure advertisements
- Leverages existing esp32_ble infrastructure
Test coverage:
- Basic sensor/binary sensor configuration tests
- Encryption test configuration
- Multi-platform support (ESP32, ESP32-C3, ESP32-S3 with IDF)
Closes: https://github.com/orgs/esphome/discussions/3235
Claude