mesh-cam

A two-board off-grid camera node for a Meshtastic mesh.

• Heltec LoRa 32 V3 runs stock Meshtastic with the Serial Module enabled. It is the LoRa radio + mesh bridge.
• Seeed XIAO ESP32-S3 Sense runs the firmware in src/main.cpp: camera motion detection + a command parser, with full-res JPEG stills saved to microSD.

The two boards talk over a 3-wire UART. The mesh carries text only (alerts and commands) — images stay on the SD card (LoRa has nowhere near the bandwidth for photos).

            LoRa mesh (text only)
   +--------------------------------------+
   |                                      |
[Heltec V3] --UART 38400-- [XIAO S3 Sense]-+- microSD (JPEG stills)
 Meshtastic   33/34<->44/43   camera + motion
 Serial Mod                   + command parser

 motion  -> "MOTION at cam1"  -> mesh
 "snap"  -> mesh -> Heltec -> XIAO -> photo to SD -> "SAVED ..." -> mesh

Wiring (3 jumpers)

XIAO S3 Sense	->	Heltec V3	Meaning
D6 / GPIO43 (TX)	->	GPIO33 (RX)	XIAO talks, Heltec listens
D7 / GPIO44 (RX)	->	GPIO34 (TX)	mesh -> XIAO commands
GND	->	GND	common ground (required)

Do NOT use Heltec GPIO 43/44 for the Serial Module — open bug where the USB-C/UART pins won't accept serial input. Use 33/34 as above.

Heltec V3 — enable the Serial Module

Install the CLI (pip install meshtastic), plug the Heltec in over USB, then:

meshtastic --set serial.enabled true
meshtastic --set serial.mode TEXTMSG     # incoming serial text -> mesh broadcast
meshtastic --set serial.rxd 33           # Heltec listens here
meshtastic --set serial.txd 34           # Heltec sends here (mesh -> serial)
meshtastic --set serial.baud BAUD_38400  # MUST match the XIAO sketch

Same options exist in the app/web client under Settings -> Serial Module.

XIAO S3 Sense — build & flash (PlatformIO)

pipx install platformio        # or: pip install platformio
cd mesh-cam
pio run                         # compile
pio run --target upload         # flash (hold BOOT if it won't auto-enter)
pio device monitor              # watch serial @115200

Board: XIAO_ESP32S3, PSRAM enabled (set in platformio.ini). The esp32-camera, SD_MMC, and FS libraries ship with the Arduino-ESP32 core, so no lib_deps are needed.

Tuning (src/main.cpp)

• MOTION_FRAC / PIXEL_DELTA — raise to reduce false alerts, lower to be more sensitive.
• COOLDOWN_MS — minimum gap between mesh alerts; your LoRa duty-cycle guardrail.
• handleCommand() — add keywords beyond snap (e.g. status, arm, disarm).

Home Assistant bridge

See HOMEASSISTANT.md for relaying the field node to Home Assistant: the Cardputer ADV at home acts as a WiFi MQTT gateway, uplinking everything it hears (including MOTION at cam1) to HA's Mosquitto broker. Example HA entities/automations are in ha/.

Building it

BUILDLOG.md is a phase-by-phase checklist to tick through during the actual build, ordered so each phase isolates one failure point.