Use cargo features to allow fine-grain control of the library.

Cargo.toml

@@ -16,15 +16,18 @@ edition = "2018"
 links = "cortex-m"  # prevent multiple versions of this crate to be linked together
 
 [dependencies]
-bare-metal = { version = "0.2.0", features = ["const-fn"] }
+bare-metal = { version = "0.2.0", features = ["const-fn"], optional = true }
 volatile-register = "0.2.0"
 bitfield = "0.13.2"
-embedded-hal = "0.2.4"
+embedded-hal = { version = "0.2.4", optional = true }
 
 [features]
+default = ["interrupt", "delay"]
 cm7-r0p1 = []
 inline-asm = []
 linker-plugin-lto = []
+interrupt = ["bare-metal"]
+delay = ["embedded-hal"]
 
 [workspace]
 members = ["xtask", "cortex-m-semihosting", "panic-semihosting", "panic-itm"]

src/lib.rs

@@ -77,7 +77,9 @@
 //    to be applied to the struct).
 #![deny(clippy::missing_inline_in_public_items)]
 
+#[cfg(feature = "interrupt")]
 extern crate bare_metal;
+
 extern crate volatile_register;
 
 #[macro_use]
@@ -88,12 +90,18 @@ mod macros;
 pub mod asm;
 #[cfg(armv8m)]
 pub mod cmse;
+
+#[cfg(feature = "delay")]
 pub mod delay;
+#[cfg(feature = "interrupt")]
 pub mod interrupt;
 #[cfg(all(not(armv6m), not(armv8m_base)))]
 pub mod itm;
 pub mod peripheral;
+
+#[cfg(feature = "delay")]
 pub mod prelude;
+
 pub mod register;
 
 pub use crate::peripheral::Peripherals;

src/peripheral/mod.rs

@@ -58,6 +58,7 @@
 use core::marker::PhantomData;
 use core::ops;
 
+#[cfg(feature = "interrupt")]
 use crate::interrupt;
 
 #[cfg(not(armv6m))]
@@ -156,6 +157,7 @@ static mut TAKEN: bool = false;
 impl Peripherals {
     /// Returns all the core peripherals *once*
     #[inline]
+    #[cfg(feature = "interrupt")]
     pub fn take() -> Option<Self> {
         interrupt::free(|_| {
             if unsafe { TAKEN } {

src/peripheral/nvic.rs

@@ -4,7 +4,9 @@ use volatile_register::RW;
 #[cfg(not(armv6m))]
 use volatile_register::{RO, WO};
 
+#[cfg(feature = "interrupt")]
 use crate::interrupt::InterruptNumber;
+#[cfg(feature = "interrupt")]
 use crate::peripheral::NVIC;
 
 /// Register block
@@ -74,6 +76,7 @@ pub struct RegisterBlock {
     pub stir: WO<u32>,
 }
 
+#[cfg(feature = "interrupt")]
 impl NVIC {
     /// Request an IRQ in software
     ///

src/prelude.rs

@@ -1,3 +1,4 @@
 //! Prelude
 
+#[cfg(feature = "delay")]
 pub use embedded_hal::prelude::*;