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The GPIO pin model: levels, pull and drive configuration, interrupt edges, and active polarity.
A GPIO pin is the simplest interface on a board: one line that is either high or low. The logic that still has to be right is the meaning of that level. A button wired to ground through a pull-up reads low when pressed; a relay board sold as “active low” switches on when its input is driven low. Treating “pressed” or “on” as if it always meant a high level is a classic inversion bug. This module carries the small set of GPIO concepts so that mapping is written down once rather than scattered through call sites.
Enums§
- Direction
- Whether a pin reads its line (input) or drives it (output).
- Drive
- How an output pin drives its two states.
- Edge
- The signal transition that triggers a pin interrupt.
- Level
- The physical voltage level on a pin.
- Polarity
- Whether a signal is asserted by a high or a low physical level.
- Pull
- The internal pull resistor applied to an input pin.