diff --git a/Cargo.toml b/Cargo.toml
index 0f738c4..03325f0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,8 +9,6 @@ edition = "2021"
 # path = "src/bin/i2c.rs"
 
 
-# [net]
-# git-fetch-with-cli = true
 
 [dependencies]
 # cortex-m = "0.7.0"
diff --git a/src/bin/usb_hs.rs b/src/bin/usb_hs.rs
index 0d0d0e6..eafc614 100644
--- a/src/bin/usb_hs.rs
+++ b/src/bin/usb_hs.rs
@@ -2,17 +2,9 @@
 #![no_std]
 #![no_main]
 #![feature(type_alias_impl_trait)]
-
 use core::panic::PanicInfo;
-
 use defmt_rtt as _;
 use embassy_executor::Spawner;
-// use embassy_usb::{
-//     class::cdc_acm::{CdcAcmClass, State},
-//     driver::EndpointError,
-//     Builder,
-// };
-// use stm32_metapac;
 
 use u5_lib::{
     usb_otg_hs::mod_new::{cdc_acm_ep2_read },
@@ -21,13 +13,6 @@ use u5_lib::{
 use u5_lib::usb_otg_hs::control_pipe::setup_process;
 use u5_lib::usb_otg_hs::power::power_up_init;
 
-// define defmt format
-#[derive(defmt::Format)]
-pub enum UsbError {
-    BufferOverflow,
-    Disabled,
-}
-
 const GREEN: gpio::GpioPort = gpio::PB7;
 
 #[embassy_executor::main]
@@ -40,24 +25,35 @@ async fn main(spawner: Spawner) {
     defmt::info!("setup led finished!");
     // spawner.spawn(btn()).unwrap();
     // spawner.spawn(pwr::vddusb_monitor_up()).unwrap();
-    // spawner.spawn(usb_task()).unwrap();
     // use some delay to wait for usb power up
     pwr::vddusb_monitor_up_tmp();
     power_up_init();
     defmt::info!("vddusb monitor finished!");
-    //
+    spawner.spawn(usb_task()).unwrap();
 
     spawner.spawn(setup_process()).unwrap();
 
     defmt::info!("usb init finished!");
     loop {
         exti::EXTI13_PC13.wait_for_raising().await;
-        // spawner.spawn(cdc_acm_ep2_read()).unwrap();
-        cdc_acm_ep2_read().await;
         GREEN.toggle();
     }
 }
 
+#[embassy_executor::task]
+async fn usb_task() {
+    // the maximum size of the command is 64 bytes
+    defmt::info!("start usb handler");
+    // wait for end of suspend here
+
+    loop {
+        // todo: in read function, we need to wait for usbepen to be set.
+        let ret = cdc_acm_ep2_read().await; 
+        defmt::info!("read ret: {:?}", ret);
+    }
+}
+
+
 #[panic_handler]
 fn panic(_info: &PanicInfo) -> ! {
     defmt::info!("panic");
@@ -69,93 +65,4 @@ fn panic(_info: &PanicInfo) -> ! {
     );
 
     loop {}
-}
-
-// #[embassy_executor::task]
-// pub async fn usb_task() {
-//     let _ep_out_buffer = [0u8; 256];
-//     let mut config = usb_otg_hs::Config::default();
-//     config.vbus_detection = false;
-//     let driver = usb_otg_hs::Driver::new(config, gpio::USB_DM_PA11, gpio::USB_DP_PA12);
-//
-//     // // Create embassy-usb Config
-//     let mut config = embassy_usb::Config::new(0xaaaa, 0xefba);
-//     config.manufacturer = Some("ggeta");
-//     config.product = Some("USB-serial example");
-//     config.serial_number = Some("12345678");
-//
-//     config.device_class = 0xEF;
-//     config.device_sub_class = 0x02;
-//     config.device_protocol = 0x01;
-//     config.composite_with_iads = true;
-//
-//     let mut device_descriptor = [0; 512];
-//     let mut config_descriptor = [0; 512];
-//     let mut bos_descriptor = [0; 512];
-//     let mut control_buf = [0; 64];
-//     let mut msos_descriptor = [0; 512];
-//
-//     let mut state = State::new();
-//     // USART1.send("starting usb task new!\n\n".as_bytes());
-//
-//     let mut builder = Builder::new(
-//         driver,
-//         config,
-//         &mut device_descriptor,
-//         &mut config_descriptor,
-//         &mut bos_descriptor,
-//         &mut msos_descriptor,
-//         &mut control_buf,
-//     );
-//
-//     let mut class = CdcAcmClass::new(&mut builder, &mut state, 64);
-//     // USART1.send("declare class success!\n".as_bytes());
-//     // Build the builder.
-//     let mut usb = builder.build();
-//     // USART1.send("success!\n".as_bytes());
-//     let usb_fut = usb.run(); // Run the USB device.
-//     let handler_fut = async {
-//         loop {
-//             class.wait_connection().await;
-//             defmt::info!("connected");
-//             let _ = usb_handler(&mut class).await;
-//             defmt::info!("disconnected");
-//         }
-//     };
-//     // USART1.send("start usb task success!\n".as_bytes());
-//     join(usb_fut, handler_fut).await; // Run everything concurrently.
-// }
-
-// struct Disconnected {}
-
-// impl From<EndpointError> for Disconnected {
-//     fn from(val: EndpointError) -> Self {
-//         match val {
-//             EndpointError::BufferOverflow => panic!("Buffer overflow"),
-//             EndpointError::Disabled => Disconnected {},
-//         }
-//     }
-// }
-//
-// async fn usb_handler<'d>(
-//     class: &mut CdcAcmClass<'d, usb_otg_hs::Driver>,
-// ) -> Result<(), Disconnected> {
-//     let mut buf: [u8; 128] = [0; 128];
-//     // the maximum size of the command is 64 bytes
-//     defmt::info!("start usb handler");
-//     loop {
-//         // select(future1, future2)
-//         let ret = class.read_packet(&mut buf).await;
-//         match ret {
-//             Ok(n) => {
-//                 defmt::info!("read {} bytes", n);
-//                 class.write_packet(&buf[0..n]).await.unwrap();
-//             }
-//             Err(e) => {
-//                 defmt::info!("error: {:?}", e);
-//                 return Err(e.into());
-//             }
-//         }
-//         // class.write_packet(&buf[0..n]).await.unwrap();
-//     }
-// }
+}
\ No newline at end of file