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singleton

A value of which only one can ever exist, such as the one handle to a chip's GPIO8 pin.

In embedded Rust a peripheral singleton is the unique value of a peripheral's type, handed out once by the HAL (esp_hal::init returns Peripherals), so ownership of the value is ownership of the hardware.

Examples

  • esp_hal::init returns Peripherals once, and its GPIO8 field is the only handle to the fan pin; a second init call panics.

  • If the heater setup is copy-pasted from the fan's and still names peripherals.GPIO8, the compiler rejects it because GPIO8 was already moved into the fan.

See also

borrow checker memory safe peripheral access crate
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