diff --git a/src/usb.rs b/src/usb.rs
index 9a6fd9b9..f5c45dba 100644
--- a/src/usb.rs
+++ b/src/usb.rs
@@ -1,5 +1,9 @@
 //! USB peripheral
 
+//! Requires the `stm32-usbd` feature.
+//! See https://github.com/stm32-rs/stm32f1xx-hal/tree/master/examples
+//! for usage examples
+
 use crate::pac::{RCC, USB};
 use stm32_usbd::UsbPeripheral;