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Functional Decomposition

Functional decomposition breaks down an electronic product into its constituent functional units. AP 210 captures both the functional structure and its relationship to the physical implementation.

The Wheatstone Bridge Example

The Wheatstone Bridge is used throughout AP 210 training as a canonical example. It demonstrates how a simple circuit can be decomposed functionally and then mapped to physical components.

Functional View

A Wheatstone Bridge consists of:

  • Four resistors in a diamond arrangement

  • A voltage source across one diagonal

  • A measurement point (galvanometer) across the other diagonal

Functional Decomposition

Wheatstone Bridge
  ├── Voltage Source
  ├── Resistor R1 (known)
  ├── Resistor R2 (known)
  ├── Resistor R3 (variable)
  ├── Resistor Rx (unknown)
  └── Galvanometer

Modeling in AP 210

Functional decomposition in AP 210 uses:

  • functional_unit - A logical functional block

  • functional_unit_terminal - A connection point on a functional unit

  • functional_unit_usage - An instance of a functional unit in a decomposition

  • connectivity - How functional units connect to each other

Mapping Function to Physics

The key insight is that functional units map to physical components:

Functional UnitPhysical Component

Resistor R1

Surface mount resistor, 0402 package

Resistor R2

Surface mount resistor, 0402 package

Resistor R3

Potentiometer, through-hole

Resistor Rx

Device under test

Galvanometer

Measurement instrument

This mapping is captured in AP 210 through design_functional_unit_allocation entities that link functional units to their physical implementations.