Most embedded developers start by grabbing a dev board and working bottom-up from hardware drivers to application logic. This approach delays customer-visible features, slows feedback loops, and risks wasted effort if the application direction is wrong. A top-down strategy inverts this: start with application-layer code and mock or simulate hardware interfaces (USART as a network socket, simulated I2C, test fixtures for sensors) until the feature is validated. This yields faster feature validation, decoupled architecture that's easier to test and port, and stronger separation between business logic and hardware details. Low-level code is written only once it's proven necessary. Hardware-specific work (peripheral evaluation, firmware update strategies) can still be isolated without letting it drive the entire development sequence.
