Cargo Features

STM32L151 has no features set by default.

stm32l151 = { version = "0.2.1", features = ["rt"] }
rt = cortex-m-rt

Affects stm32l151::interrupt.INTERRUPTS, stm32l151::interrupt.interrupt

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

cortex-m-rt rt?

Enables cortex-m-rt ^0.3.12