Sensing

Resistor identification

A physical piece provides a resistor to ground. A reference resistor creates a divider read by an ADC:

Vexc (5V in the original concept; verify against ADC supply/reference)
 │
10kΩ reference resistor
 │
 ├──────── ADC input
 │
Piece resistor + contact resistance
 │
GND

This is a conceptual circuit, not a verified schematic. The empty slot approaches the excitation voltage, so the ADC must tolerate that voltage even with no piece fitted. The final excitation voltage, ADC reference, and input protection depend on the actual controller configuration.

For an ideal divider:

Vadc = Vexc × Rpiece / (Rref + Rpiece)
Rpiece = Rref × Vadc / (Vexc − Vadc)

The inferred resistance includes the contact path. Near an open circuit the denominator approaches zero; classify the empty range before attempting the resistance calculation. A near-short or an ambiguous value must not silently become a player identity.

Seven independent analog inputs are intended per hex: three roads, three buildings, and one land tile. Each uses its own 10kΩ reference resistor. The current concept omits the CD74HC4067 analog multiplexer, subject to verifying the CH32 pin allocation.

Classification

Road values distinguish four players. Building values distinguish four settlements and four cities. Land values distinguish resource types. Exact values and acceptance bands belong in the resistor registry; none have been assigned.

Space classifications to accommodate resistor tolerances, ADC variation, and contact resistance. Use calibration and stable samples instead of equality against one ADC reading.

Robber contact

Only presence is needed because there is one robber. The proposed digital arrangement is absent = HIGH and present = LOW, with a pull-up and a contact to ground. Pin, pull-up arrangement, and mechanical contact remain undefined. Debounce the signal. If multiple hexes report a robber, retain the observations and surface the inconsistency rather than arbitrarily choosing one.

For processing steps see Smart Hex software; for contact mechanics see Playable Pieces hardware.