Start with the use case
Describe what the device must do, who will use it and where it will operate. This separates essential functions from optional features.
Power and connections
Describe the power source, external sensors and actuators. Identify existing equipment the board must communicate with.
Enclosure and operation
Dimensions, connectors, mounting and temperature conditions affect layout. Photos of the installation and existing drawings can help.
Acceptance criteria
Agree on how the prototype will be tested and which files will be delivered. This makes the scope easier to define.
