Charger

The Charger component is by nature closely associated with the battery, and could be tightly coupled as an extension to that subsystem and sharing the battery Controller. However, that would undermine the modular component advantages of ODP because the charger is an independent component and could be matched with different battery configurations.

Battery and Charger are two independent components, each with their own Device, Controller, and Service. They are registered individually with the embedded-services framework and communicate only via messaging through our comms implementation. This models real-world physical separation, where a charging circuit and a battery pack are distinct units that coordinate via well-defined interfaces.

graph TD
    subgraph EmbeddedServices
        Registry[Service Registry]
    end

    subgraph Battery
        BatteryDevice[BatteryDevice -- _impl Device_]
        BatteryController[BatteryController -- _impl Controller_]
    end

    subgraph Charger
        ChargerDevice[ChargerDevice -- _impl Device_]
        ChargerController[ChargerController -- _impl Controller_]
    end

    BatteryDevice --> BatteryController
    ChargerDevice --> ChargerController

    BatteryController --> Registry
    ChargerController --> Registry
    BatteryDevice --> Registry
    ChargerDevice --> Registry

The BatteryDevice contains both the SmartBattery implementation (as battery) and the Charger implementation (as charger). The BatteryDevice is registered with the BatteryController, which polls the battery, interprets the data, and invokes charger methods to respond to battery needs.

sequenceDiagram
    participant ChargerController
    participant BatteryController

    ChargerController->>BatteryController: Request battery status
    BatteryController-->>ChargerController: BatteryState _voltage, temp, soc_

    ChargerController->>BatteryController: Apply charging parameters

    BatteryController-->>ChargerController: Ack / Updated status

When paired with the battery, the two work in concert:

sequenceDiagram
    participant PolicyManager
    participant BatteryController
    participant BatteryDevice
    participant Battery
    participant ChargerController
    participant ChargerDevice
    participant Charger

    PolicyManager->>BatteryController: poll()
    BatteryController->>BatteryDevice: read_status()
    BatteryDevice->>Battery: get_status()
    Battery-->>BatteryDevice: BatteryStatus { low_charge: true }
    BatteryDevice-->>BatteryController: BatteryStatus
    BatteryController-->>PolicyManager: BatteryStatus

    PolicyManager->>ChargerController: apply_charge(mA, mV)
    ChargerController->>ChargerDevice: charging_current(mA)
    ChargerDevice->>Charger: set_current(mA)
    Charger-->>ChargerDevice: Ok(mA)
    ChargerDevice-->>ChargerController: Ok(mA)

    ChargerController->>ChargerDevice: charging_voltage(mV)
    ChargerDevice->>Charger: set_voltage(mV)
    Charger-->>ChargerDevice: Ok(mV)
    ChargerDevice-->>ChargerController: Ok(mV)

    ChargerController->>PolicyManager: Charging applied

Here, the controller polls the battery state, and the battery indicates that is has a low charge. The controller determines the charging parameters and instructs the charger. The battery charge level should now improve as the charge is applied over time.