High-level component diagram

graph TD
    main["main.cpp"]
    ED["EventDispatcher"]
    PM["ProfileManager"]
    AH["Action hierarchy"]
    LED["LEDController (ILEDController)"]
    BTN["ButtonController (IButtonController)"]
    BLE["BleKeyboardAdapter (IBleKeyboard)"]
 
    main --> ED
    main --> PM
    main --> LED
    main --> BTN
    main --> BLE
    ED --> PM
    PM --> AH
    AH --> BLE
    AH --> LED

Action class hierarchy

classDiagram
    Action <|-- SendAction
    Action <|-- NonSendAction
    SendAction <|-- SendStringAction
    SendAction <|-- SendCharAction
    SendAction <|-- SendKeyAction
    SendAction <|-- SendMediaKeyAction
    NonSendAction <|-- DelayedAction
    NonSendAction <|-- SerialOutputAction
    NonSendAction <|-- SerialAction

Component table

Component	File	Pattern	Responsibility
`main.cpp`	`src/main.cpp`	Composition root	Wires all components together; owns the main loop
`EventDispatcher`	`include/event_dispatcher.h`	Observer	Registers button handlers; dispatches button presses to the correct action
`ProfileManager`	`include/profile_manager.h`	Strategy + Composite	Stores per-profile action sets; handles profile switching and LED feedback
Action hierarchy	`lib/PedalLogic/include/`	Strategy	Polymorphic actions executed on button press
`LEDController`	`lib/hardware/esp32/`	Adapter	Abstracts LED GPIO
`ButtonController`	`lib/hardware/esp32/`	Adapter	Abstracts button GPIO with debounce
`BleKeyboardAdapter`	`lib/hardware/esp32/`	Adapter	Wraps the ESP32 BLE Keyboard library behind `IBleKeyboard`
`ConfigLoader`	`lib/PedalLogic/src/config_loader.cpp`	—	Reads `pedal_config.json` from LittleFS and builds the action graph

Hardware abstraction seam

The codebase is split into hardware-independent logic (lib/PedalLogic) and hardware-specific drivers (lib/hardware/esp32, lib/hardware/nrf52840).

The seam is defined by three interface classes:

ILEDController — set LED state
IButtonController — read button state
IBleKeyboard — send key events

Hardware-independent code (EventDispatcher, ProfileManager, Action hierarchy) depends only on these interfaces. Platform-specific code implements them.

The HOST_TEST_BUILD preprocessor flag enables building the logic layer on a development machine without any ESP32 or Arduino dependencies. When this flag is set, Arduino-specific headers are replaced by test/fakes/arduino_shim.h, and hardware implementations are replaced by mock classes from test/mocks/.

This means the full logic of the pedal can be tested with GoogleTest on any machine, without hardware.

Memory management

All dynamic memory is managed via std::unique_ptr.
RAII: resources are acquired in constructors and released automatically in destructors.
No raw new or delete in application code.