Data Flow

This diagram shows how data moves through the Multiflexmeter system.

%%{init: {'theme':'base', 'themeVariables': { 'fontSize':'16px'}}}%%
flowchart TB
    subgraph PHYS["🌍 Physical Environment"]
        MILL["🏛️ Mallemolen Mill
Temperature, Humidity, etc."]
    end

    subgraph SENSE["📡 Sensing Layer"]
        SENSOR["🔍 I2C Sensor (0x36)
CMD: 0x10 (trigger)
CMD: 0x11 (read)"]
    end

    subgraph DEVICE["📟 Multiflexmeter Device"]
        direction TB

        subgraph FW["💻 Firmware Layer"]
            direction LR
            SINTF["📊 Sensor Interface
sensors.cpp"]
            MAIN["🎛️ Main Controller
main.cpp"]
            CONF["⚙️ Config Manager
rom_conf.cpp"]
        end

        subgraph HW["🔧 Hardware Layer"]
            direction LR
            I2CDRV["🔌 I2C Driver @ 80kHz
smbus.cpp"]
            NETSTACK["📶 LoRaWAN Stack
LMIC Library"]
            EEPROM["💾 EEPROM
41 bytes config"]
        end
    end

    subgraph NET["☁️ Network Infrastructure"]
        GW["📡 LoRaWAN Gateway
EU868 Band"]
        TTN["🌐 The Things Network
OTAA Join / Downlink"]
    end

    subgraph BACK["💾 Backend Systems"]
        direction TB
        SERVER["💻 Backend Server
MQTT/HTTP Integration"]
        DB[("🗄️ Database
Time Series Data")]
        UI["📱 Web Interface
Visualization"]
    end

    %% Uplink Data Flow (Solid Lines)
    MILL ==>|"Environmental
Changes"| SENSOR
    SENSOR ==>|"I2C Raw Data
[bytes]"| I2CDRV
    I2CDRV ==>|"Parsed Bytes"| SINTF
    SINTF ==>|"Sensor Values"| MAIN
    MAIN ==>|"LoRaWAN Payload
Port 1: Data
Port 2: Version"| NETSTACK
    CONF <-.->|"Read/Write
DevEUI, AppKey
Interval"| EEPROM
    NETSTACK ==>|"868MHz RF
SF7-SF12"| GW
    GW ==>|"Internet
Forwarding"| TTN
    TTN ==>|"JSON Payload
+ Metadata"| SERVER
    SERVER ==>|"Store"| DB
    DB ==>|"Query"| UI

    %% Downlink Command Flow (Dashed Lines)
    UI -.->|"User Commands"| SERVER
    SERVER -.->|"Downlink Payload"| TTN
    TTN -.->|"Scheduled
Downlink"| GW
    GW -.->|"RX1/RX2
Window"| NETSTACK
    NETSTACK -.->|"Decode"| MAIN
    MAIN -.->|"0xDEAD: Reset
0x10: Interval
0x11: Sensor Cmd"| CONF
    MAIN -.->|"Forward
Commands"| SINTF
    SINTF -.->|"I2C Write"| I2CDRV
    I2CDRV -.->|"Execute"| SENSOR

    %% Styling
    style PHYS fill:#d4edda,stroke:#28a745,stroke-width:3px
    style SENSE fill:#cfe2ff,stroke:#084298,stroke-width:3px
    style DEVICE fill:#fff3cd,stroke:#856404,stroke-width:3px
    style NET fill:#e7f1ff,stroke:#004085,stroke-width:3px
    style BACK fill:#f8d7da,stroke:#721c24,stroke-width:3px

    style MILL fill:#a3e4d7,stroke:#196f3d,stroke-width:2px
    style SENSOR fill:#aed6f1,stroke:#1f618d,stroke-width:2px
    style I2CDRV fill:#fad7a0,stroke:#b9770e,stroke-width:2px
    style SINTF fill:#fad7a0,stroke:#b9770e,stroke-width:2px
    style MAIN fill:#fad7a0,stroke:#b9770e,stroke-width:2px
    style CONF fill:#fad7a0,stroke:#b9770e,stroke-width:2px
    style NETSTACK fill:#fad7a0,stroke:#b9770e,stroke-width:2px
    style EEPROM fill:#d7bde2,stroke:#6c3483,stroke-width:2px
    style GW fill:#aed6f1,stroke:#1f618d,stroke-width:2px
    style TTN fill:#aed6f1,stroke:#1f618d,stroke-width:2px
    style SERVER fill:#f5b7b1,stroke:#943126,stroke-width:2px
    style DB fill:#f5b7b1,stroke:#943126,stroke-width:2px
    style UI fill:#f5b7b1,stroke:#943126,stroke-width:2px

Data Format at Each Stage

1. Sensor → Device (I2C)

Command: 0x10 (trigger) → No response
Command: 0x11 (read) → [length][byte1][byte2]...[byteN]

2. Device → Network (LoRaWAN)

Port: 1 (sensor data)
Payload: [sensor_data_bytes]

Port: 2 (version ping)
Payload: [fw_version_msb][fw_version_lsb][hw_version_msb][hw_version_lsb]

3. Network → Backend (IP)

{
  "device_id": "...",
  "timestamp": "...",
  "payload": "base64_encoded_data",
  "port": 1,
  "rssi": -120,
  "snr": 5.2
}

4. Backend Commands → Device

Reset: 0xDE 0xAD
Set Interval: 0x10 [interval_msb] [interval_lsb]
Sensor Command: 0x11 [command_bytes...]

Configuration Flow

flowchart TD
    Start([Device Boot]) --> Load[Load Settings from EEPROM]
    Load --> Check{Valid Config?}
    Check -->|No| Default[Use Default Settings]
    Check -->|Yes| Use[Use Loaded Settings]

    Default --> Run[Device Running]
    Use --> Run

    Run --> Receive{Downlink
Received?}
    Receive -->|No| Run
    Receive -->|Yes| Update[Update Setting]
    Update --> Save[Save to EEPROM]
    Save --> Apply[Apply New Setting]
    Apply --> Run

    style Load fill:#e1f5ff
    style Save fill:#ffe1e1
    style Apply fill:#e1ffe1

Settings Stored in EEPROM (41 bytes)

Offset	Size	Field	Description
0-3	4	MAGIC	”MFM\0” identifier
4-5	2	HW_VERSION	Hardware version
6-13	8	APP_EUI	LoRaWAN Application EUI
14-21	8	DEV_EUI	LoRaWAN Device EUI
22-37	16	APP_KEY	LoRaWAN Application Key
38-39	2	INTERVAL	Measurement interval (seconds)
40	1	TTN_POLICY	Use TTN fair use policy

All settings persist across resets and power cycles.