diff --git a/src/lib.rs b/src/lib.rs
index 5fd6f94..581007b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,9 @@
 #![no_std]
+mod usb_constants;
 mod midi_device;
 mod notes;
 
 pub use usb_device::{Result,UsbError};
+pub use crate::usb_constants::USB_CLASS_NONE;
 pub use crate::midi_device::*;
 pub use crate::notes::Note;
\ No newline at end of file
diff --git a/src/midi_device.rs b/src/midi_device.rs
index 8d486fe..3534ae3 100644
--- a/src/midi_device.rs
+++ b/src/midi_device.rs
@@ -1,22 +1,9 @@
 use usb_device::class_prelude::*;
 use usb_device::Result;
 use crate::notes::Note;
+use crate::usb_constants::*;
 
-pub const USB_CLASS_NONE : u8 = 0x00;
-const USB_AUDIO_CLASS: u8 = 0x01;
-const USB_AUDIOCONTROL_SUBCLASS: u8 = 0x01;
-const USB_MIDISTREAMING_SUBCLASS: u8 =0x03;
-const MIDI_IN_JACK_SUBTYPE : u8 = 0x02;
-const MIDI_OUT_JACK_SUBTYPE : u8 = 0x03;
-const EMBEDDED : u8 = 0x01;
-const CS_INTERFACE: u8 = 0x24;
-const CS_ENDPOINT: u8 = 0x25;
-const HEADER_SUBTYPE: u8 = 0x01;
-const MS_HEADER_SUBTYPE: u8 = 0x01;
-const MS_GENERAL: u8 = 0x01;
-
-
-const MIDI_IN_SIZE: u8 = 0x06;
+//const MIDI_IN_SIZE: u8 = 0x06;
 const MIDI_OUT_SIZE: u8 = 0x09;
 
 pub struct MidiClass<'a,B: UsbBus> {
diff --git a/src/usb_constants.rs b/src/usb_constants.rs
new file mode 100644
index 0000000..8ec3203
--- /dev/null
+++ b/src/usb_constants.rs
@@ -0,0 +1,14 @@
+
+pub const USB_CLASS_NONE : u8 = 0x00;
+pub const USB_AUDIO_CLASS: u8 = 0x01;
+pub const USB_AUDIOCONTROL_SUBCLASS: u8 = 0x01;
+pub const USB_MIDISTREAMING_SUBCLASS: u8 =0x03;
+//pub const MIDI_IN_JACK_SUBTYPE : u8 = 0x02;
+pub const MIDI_OUT_JACK_SUBTYPE : u8 = 0x03;
+pub const EMBEDDED : u8 = 0x01;
+pub const CS_INTERFACE: u8 = 0x24;
+pub const CS_ENDPOINT: u8 = 0x25;
+pub const HEADER_SUBTYPE: u8 = 0x01;
+pub const MS_HEADER_SUBTYPE: u8 = 0x01;
+pub const MS_GENERAL: u8 = 0x01;
+