oneWireTemperature

Index-to-field accessors for the per-channel telemetry fields.

Wire generates one named property per channel, so indexed access needs an explicit map rather than a list lookup. Each field is optional, making null the only "channel absent" signal — a returned 0f is a real reading (0 V on an unloaded ADC input, 0°C on a probe at freezing), so callers must not treat zero as missing.

Reading past TELEMETRY_CHANNEL_COUNT returns null rather than throwing, so a firmware that grows the channel range degrades to "not shown" instead of crashing.