diff --git a/src/types/usb_device.rs b/src/types/usb_device.rs
index 6de6d7b..5e0c5c0 100644
--- a/src/types/usb_device.rs
+++ b/src/types/usb_device.rs
@@ -1,30 +1,26 @@
-use core::cmp::max;
-
 use avr_device::{
     atmega32u4::{PLL, USB_DEVICE},
-    interrupt::{free, CriticalSection, Mutex},
+    interrupt::{CriticalSection, Mutex},
 };
 use usb_device::{
-    bus::{PollResult, UsbBus},
-    endpoint::{EndpointAddress, EndpointType},
-    Result as UsbResult, UsbDirection, UsbError,
+    bus::UsbBusAllocator,
+    endpoint::EndpointType,
+    UsbDirection, UsbError,
 };
 
 #[allow(unused)]
 #[derive(Default, Copy, Clone)]
 pub(crate) struct USBEndpoint {
-    is_allocated: bool,
-    size: u8,
-    ep_type: u8,
-    ep_dir: bool,
-    banks: u8,
+    pub(crate) is_allocated: bool,
+    pub(crate) size: u8,
+    pub(crate) ep_type: u8,
+    pub(crate) ep_dir: bool,
+    pub(crate) banks: u8,
 }
 
-const ENDPOINTS_ALLOC_LAYOUT: [u16; 7] = [64, 256, 64, 64, 64, 64, 64];
-
 impl USBEndpoint {
     #[inline]
-    fn set_type(&mut self, ep_type: EndpointType) {
+    pub(crate) fn set_type(&mut self, ep_type: EndpointType) {
         self.ep_type = match ep_type {
             EndpointType::Control => 0, // 0 = 0b00
             EndpointType::Isochronous {
@@ -37,7 +33,7 @@ impl USBEndpoint {
     }
 
     #[inline]
-    fn set_dir(&mut self, dir: UsbDirection) {
+    pub(crate) fn set_dir(&mut self, dir: UsbDirection) {
         self.ep_dir = match dir {
             UsbDirection::In => true,
             UsbDirection::Out => false,
@@ -45,7 +41,7 @@ impl USBEndpoint {
     }
 
     #[inline]
-    fn set_size(&mut self, size: u16) {
+    pub(crate) fn set_size(&mut self, size: u16) {
         self.size = match size {
             8 => 0b000,
             16 => 0b001,
@@ -59,30 +55,31 @@ impl USBEndpoint {
     }
 }
 
-pub struct UsbDevice<const L: usize> {
-    pll: Mutex<PLL>,
-    usb: Mutex<USB_DEVICE>,
-    ep_table: [USBEndpoint; L],
-    dpram_already_used: u16,
+pub(crate) struct UsbDevice<const L: usize> {
+    pub(crate) pll: Mutex<PLL>,
+    pub(crate) usb: Mutex<USB_DEVICE>,
+    pub(crate) ep_table: [USBEndpoint; L],
+    pub(crate) dpram_already_used: u16,
 }
 
-const DPRAM_SIZE: u16 = 832;
+pub(crate) const DPRAM_SIZE: u16 = 832;
+pub(crate) const ENDPOINTS_ALLOC_LAYOUT: [u16; 7] = [64, 256, 64, 64, 64, 64, 64];
 
 impl<const L: usize> UsbDevice<L> {
     #[inline]
-    pub fn new(pll: PLL, usb: USB_DEVICE) -> Self {
+    pub(crate) fn new(pll: PLL, usb: USB_DEVICE) -> UsbBusAllocator<Self> {
         let (pll, usb) = (Mutex::new(pll), Mutex::new(usb));
         let ep_table: [USBEndpoint; L] = [Default::default(); L];
-        Self {
+        UsbBusAllocator::new(Self {
             pll,
             usb,
             ep_table,
             dpram_already_used: 0,
-        }
+        })
     }
 
-    pub fn select_endpoint(
-        &mut self,
+    pub(crate) fn select_endpoint(
+        &self,
         cs: CriticalSection<'_>,
         endpoint_index: usize,
     ) -> Result<(), UsbError> {
@@ -102,7 +99,7 @@ impl<const L: usize> UsbDevice<L> {
         Ok(())
     }
 
-    pub fn configure_endpoint(
+    pub(crate) fn configure_endpoint(
         &mut self,
         cs: CriticalSection<'_>,
         endpoint_index: usize,
@@ -113,7 +110,7 @@ impl<const L: usize> UsbDevice<L> {
                 let current_endpoint = self.ep_table[endpoint_index];
 
                 // Clear interrupt. //
-                
+
                 usb.udint.modify(|_, w| w.eorsti().clear_bit());
 
                 // Enable endpoint. //
@@ -148,4 +145,3 @@ impl<const L: usize> UsbDevice<L> {
         }
     }
 }
-