Add LilyGO T-Deck Max (e-paper) base board support (#552)

2026-07-08 02:40:09 -04:00
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+# XL9555 I/O expander
+
+A driver for the `XL9555` 16-bit I2C-bus I/O expander, used by several LilyGO boards
+(e.g. T-Deck Pro Max) for power-rail enables, reset lines, and antenna/audio routing.
+Its register map is PCA9555-compatible: two 8-bit ports for input, output, polarity
+inversion, and direction, addressed as pins 0-15 (port 0 = pins 0-7, port 1 = pins 8-15).
+
+It does not support pull-up/down resistors or high-impedance outputs; requesting those
+flags returns `ERROR_NOT_SUPPORTED`.
+
+License: [Apache v2.0](LICENSE-Apache-2.0.md)