01
Physical layer
Sensors, inputs, outputs, power and wiring defined what the device could actually observe or control.
02
Firmware state model
Microcontroller code translated physical behaviour into explicit states, events, configuration and diagnostics.
03
Communication contract
Serial, HTTP, BLE or another channel carried versioned messages with identity and acknowledgement where required.
04
Test or control application
A desktop or web tool guided the user, displayed status and recorded the intended workflow.
05
Data and evidence layer
Measurements, timestamps, configuration and pass/fail context were retained for comparison and reporting.
06
Handover boundary
Documentation distinguished proven prototype behaviour from unresolved enclosure, certification, component and production risks.