Exercise 26: Bluetooth Discover

Plain BLE neighborhood sounder for LilyGO T-Beam SUPREME ESP32-S3 units. This exercise is not Reticulum and does not use LoRa.

Each unit waits for GPS UTC, GPS coordinates, PPS-backed RTC discipline, and then starts BLE advertising/scanning. AMY may run without SD logging because its card reader is defective; other units should mount SD and write logs.

Build

cd /usr/local/src/microreticulum/microReticulumTbeam/exercises/26_Bluetooth_discover
pio run -e amy
pio run -e bob
pio run -e cy
pio run -e dan
pio run -e ed
pio run -e flo
pio run -e guy

Upload example:

pio run -e bob -t upload
pio device monitor -b 115200 -p /dev/ttytBOB

Behavior

Advertises manufacturer data in this format: TBMSND|1|NODE|seq|uptime.
Accepts only advertisements with prefix TBMSND, version 1, and node name in AMY, BOB, CY, DAN, ED, FLO, GUY.
Displays heard nodes sorted by rolling RSSI average, strongest first.
Drops stale entries after 20 seconds.
Logs accepted advertisements to SD as /logs/YYYYMMDD_HHMISS_NODE_ble_seach.log.
Starts a WiFi AP for log access when SD is available.

Default web addresses:

AMY: http://192.168.23.1/
BOB: http://192.168.24.1/
CY: http://192.168.25.1/
DAN: http://192.168.26.1/
ED: http://192.168.27.1/
FLO: http://192.168.28.1/
GUY: http://192.168.29.1/

Field Procedure

Flash all units with this sounder image, each with its own environment.
Start all units where they can see sky and wait until each passes GPS/RTC startup discipline.
Place one unit near the intended origin, preferably central to a star topology.
Carry another unit and watch the OLED.
Find a position where it hears only the intended neighbor with weak or moderate RSSI.
Place it there.
Repeat outward to create a chain.
Record the topology manually before switching to the Reticulum BLE-interface firmware.

Limitations

RSSI is not a precise distance measurement.
Body position, antenna orientation, terrain, buildings, and foliage matter.
BLE advertisements are not guaranteed delivery.
Scan and advertise duty-cycle choices affect detection latency and power draw.
WiFi log download can affect BLE timing; use it for retrieving logs, not while making fine placement decisions.

Bench Acceptance Test

With AMY and BOB on the bench, AMY displays BOB with RSSI and age, and BOB displays AMY.
A third unrelated Bluetooth device nearby does not appear on OLED or accepted serial records.
If BOB is powered off, AMY ages BOB out after the stale timeout.
Serial output can be captured with:

pio device monitor -b 115200 -p /dev/ttytAMY | tee logs/ble_sounder_AMY_YYYYMMDD_HHMMSS.log

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