stm32 otg: add examples.

10 files changed, 542 insertions, 5 deletions

diff --git a/examples/stm32f4/Cargo.toml b/examples/stm32f4/Cargo.toml
index 62d3f08df..252d60855 100644
--- a/examples/stm32f4/Cargo.toml
+++ b/examples/stm32f4/Cargo.toml
@@ -10,6 +10,7 @@ embassy-sync = { version = "0.1.0", path = "../../embassy-sync", features = ["de
 embassy-executor = { version = "0.1.0", path = "../../embassy-executor", features = ["defmt", "integrated-timers"] }
 embassy-time = { version = "0.1.0", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime", "unstable-traits", "tick-hz-32_768"] }
 embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "unstable-traits", "defmt", "stm32f429zi", "unstable-pac", "memory-x", "time-driver-any", "exti"]  }
+embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt"] }
 
 defmt = "0.3"
 defmt-rtt = "0.4"
@@ -26,5 +27,5 @@ embedded-storage = "0.3.0"
 micromath = "2.0.0"
 static_cell = "1.0"
 
-usb-device = "0.2"
-usbd-serial = "0.1.1"
+[profile.release]
+debug = 2
diff --git a/examples/stm32f4/src/bin/usb_serial.rs b/examples/stm32f4/src/bin/usb_serial.rs
new file mode 100644
index 000000000..014647762
--- /dev/null
+++ b/examples/stm32f4/src/bin/usb_serial.rs
@@ -0,0 +1,106 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::{panic, *};
+use embassy_executor::Spawner;
+use embassy_stm32::time::mhz;
+use embassy_stm32::usb_otg::{Driver, Instance};
+use embassy_stm32::{interrupt, Config};
+use embassy_usb::class::cdc_acm::{CdcAcmClass, State};
+use embassy_usb::driver::EndpointError;
+use embassy_usb::Builder;
+use futures::future::join;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    info!("Hello World!");
+
+    let mut config = Config::default();
+    config.rcc.pll48 = true;
+    config.rcc.sys_ck = Some(mhz(48));
+
+    let p = embassy_stm32::init(config);
+
+    // Create the driver, from the HAL.
+    let irq = interrupt::take!(OTG_FS);
+    let mut ep_out_buffer = [0u8; 256];
+    let driver = Driver::new_fs(p.USB_OTG_FS, irq, p.PA12, p.PA11, &mut ep_out_buffer);
+
+    // Create embassy-usb Config
+    let mut config = embassy_usb::Config::new(0xc0de, 0xcafe);
+    config.manufacturer = Some("Embassy");
+    config.product = Some("USB-serial example");
+    config.serial_number = Some("12345678");
+
+    // Required for windows compatiblity.
+    // https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/kconfig/CONFIG_CDC_ACM_IAD.html#help
+    config.device_class = 0xEF;
+    config.device_sub_class = 0x02;
+    config.device_protocol = 0x01;
+    config.composite_with_iads = true;
+
+    // Create embassy-usb DeviceBuilder using the driver and config.
+    // It needs some buffers for building the descriptors.
+    let mut device_descriptor = [0; 256];
+    let mut config_descriptor = [0; 256];
+    let mut bos_descriptor = [0; 256];
+    let mut control_buf = [0; 64];
+
+    let mut state = State::new();
+
+    let mut builder = Builder::new(
+        driver,
+        config,
+        &mut device_descriptor,
+        &mut config_descriptor,
+        &mut bos_descriptor,
+        &mut control_buf,
+        None,
+    );
+
+    // Create classes on the builder.
+    let mut class = CdcAcmClass::new(&mut builder, &mut state, 64);
+
+    // Build the builder.
+    let mut usb = builder.build();
+
+    // Run the USB device.
+    let usb_fut = usb.run();
+
+    // Do stuff with the class!
+    let echo_fut = async {
+        loop {
+            class.wait_connection().await;
+            info!("Connected");
+            let _ = echo(&mut class).await;
+            info!("Disconnected");
+        }
+    };
+
+    // Run everything concurrently.
+    // If we had made everything `'static` above instead, we could do this using separate tasks instead.
+    join(usb_fut, echo_fut).await;
+}
+
+struct Disconnected {}
+
+impl From<EndpointError> for Disconnected {
+    fn from(val: EndpointError) -> Self {
+        match val {
+            EndpointError::BufferOverflow => panic!("Buffer overflow"),
+            EndpointError::Disabled => Disconnected {},
+        }
+    }
+}
+
+async fn echo<'d, T: Instance + 'd>(class: &mut CdcAcmClass<'d, Driver<'d, T>>) -> Result<(), Disconnected> {
+    let mut buf = [0; 64];
+    loop {
+        let n = class.read_packet(&mut buf).await?;
+        let data = &buf[..n];
+        info!("data: {:x}", data);
+        class.write_packet(data).await?;
+    }
+}
diff --git a/examples/stm32f7/Cargo.toml b/examples/stm32f7/Cargo.toml
index b80dbbf9c..ea4cbd808 100644
--- a/examples/stm32f7/Cargo.toml
+++ b/examples/stm32f7/Cargo.toml
@@ -11,6 +11,7 @@ embassy-time = { version = "0.1.0", path = "../../embassy-time", features = ["de
 embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "defmt", "stm32f767zi", "unstable-pac", "time-driver-any", "exti"]  }
 embassy-net = { path = "../../embassy-net", features = ["defmt", "nightly", "tcp", "dhcpv4", "medium-ethernet"] }
 embedded-io = { version = "0.4.0", features = ["async"] }
+embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt"] }
 
 defmt = "0.3"
 defmt-rtt = "0.4"
diff --git a/examples/stm32f7/src/bin/usb_serial.rs b/examples/stm32f7/src/bin/usb_serial.rs
new file mode 100644
index 000000000..688bd0dab
--- /dev/null
+++ b/examples/stm32f7/src/bin/usb_serial.rs
@@ -0,0 +1,107 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::{panic, *};
+use embassy_executor::Spawner;
+use embassy_stm32::time::mhz;
+use embassy_stm32::usb_otg::{Driver, Instance};
+use embassy_stm32::{interrupt, Config};
+use embassy_usb::class::cdc_acm::{CdcAcmClass, State};
+use embassy_usb::driver::EndpointError;
+use embassy_usb::Builder;
+use futures::future::join;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    info!("Hello World!");
+
+    let mut config = Config::default();
+    config.rcc.hse = Some(mhz(8));
+    config.rcc.pll48 = true;
+    config.rcc.sys_ck = Some(mhz(200));
+
+    let p = embassy_stm32::init(config);
+
+    // Create the driver, from the HAL.
+    let irq = interrupt::take!(OTG_FS);
+    let mut ep_out_buffer = [0u8; 256];
+    let driver = Driver::new_fs(p.USB_OTG_FS, irq, p.PA12, p.PA11, &mut ep_out_buffer);
+
+    // Create embassy-usb Config
+    let mut config = embassy_usb::Config::new(0xc0de, 0xcafe);
+    config.manufacturer = Some("Embassy");
+    config.product = Some("USB-serial example");
+    config.serial_number = Some("12345678");
+
+    // Required for windows compatiblity.
+    // https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/kconfig/CONFIG_CDC_ACM_IAD.html#help
+    config.device_class = 0xEF;
+    config.device_sub_class = 0x02;
+    config.device_protocol = 0x01;
+    config.composite_with_iads = true;
+
+    // Create embassy-usb DeviceBuilder using the driver and config.
+    // It needs some buffers for building the descriptors.
+    let mut device_descriptor = [0; 256];
+    let mut config_descriptor = [0; 256];
+    let mut bos_descriptor = [0; 256];
+    let mut control_buf = [0; 64];
+
+    let mut state = State::new();
+
+    let mut builder = Builder::new(
+        driver,
+        config,
+        &mut device_descriptor,
+        &mut config_descriptor,
+        &mut bos_descriptor,
+        &mut control_buf,
+        None,
+    );
+
+    // Create classes on the builder.
+    let mut class = CdcAcmClass::new(&mut builder, &mut state, 64);
+
+    // Build the builder.
+    let mut usb = builder.build();
+
+    // Run the USB device.
+    let usb_fut = usb.run();
+
+    // Do stuff with the class!
+    let echo_fut = async {
+        loop {
+            class.wait_connection().await;
+            info!("Connected");
+            let _ = echo(&mut class).await;
+            info!("Disconnected");
+        }
+    };
+
+    // Run everything concurrently.
+    // If we had made everything `'static` above instead, we could do this using separate tasks instead.
+    join(usb_fut, echo_fut).await;
+}
+
+struct Disconnected {}
+
+impl From<EndpointError> for Disconnected {
+    fn from(val: EndpointError) -> Self {
+        match val {
+            EndpointError::BufferOverflow => panic!("Buffer overflow"),
+            EndpointError::Disabled => Disconnected {},
+        }
+    }
+}
+
+async fn echo<'d, T: Instance + 'd>(class: &mut CdcAcmClass<'d, Driver<'d, T>>) -> Result<(), Disconnected> {
+    let mut buf = [0; 64];
+    loop {
+        let n = class.read_packet(&mut buf).await?;
+        let data = &buf[..n];
+        info!("data: {:x}", data);
+        class.write_packet(data).await?;
+    }
+}
diff --git a/examples/stm32h7/Cargo.toml b/examples/stm32h7/Cargo.toml
index d30c42b1f..ff38440a7 100644
--- a/examples/stm32h7/Cargo.toml
+++ b/examples/stm32h7/Cargo.toml
@@ -11,6 +11,7 @@ embassy-time = { version = "0.1.0", path = "../../embassy-time", features = ["de
 embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "defmt", "stm32h743bi", "time-driver-any", "exti", "unstable-pac", "unstable-traits"] }
 embassy-net = { path = "../../embassy-net", features = ["defmt", "nightly", "tcp", "dhcpv4", "medium-ethernet", "unstable-traits"] }
 embedded-io = { version = "0.4.0", features = ["async"] }
+embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt"] }
 
 defmt = "0.3"
 defmt-rtt = "0.4"
diff --git a/examples/stm32h7/src/bin/usb_serial.rs b/examples/stm32h7/src/bin/usb_serial.rs
new file mode 100644
index 000000000..b319d12c3
--- /dev/null
+++ b/examples/stm32h7/src/bin/usb_serial.rs
@@ -0,0 +1,106 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::{panic, *};
+use embassy_executor::Spawner;
+use embassy_stm32::time::mhz;
+use embassy_stm32::usb_otg::{Driver, Instance};
+use embassy_stm32::{interrupt, Config};
+use embassy_usb::class::cdc_acm::{CdcAcmClass, State};
+use embassy_usb::driver::EndpointError;
+use embassy_usb::Builder;
+use futures::future::join;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    info!("Hello World!");
+
+    let mut config = Config::default();
+    config.rcc.sys_ck = Some(mhz(400));
+    config.rcc.hclk = Some(mhz(200));
+    config.rcc.pll1.q_ck = Some(mhz(100));
+    let p = embassy_stm32::init(config);
+
+    // Create the driver, from the HAL.
+    let irq = interrupt::take!(OTG_FS);
+    let mut ep_out_buffer = [0u8; 256];
+    let driver = Driver::new_fs(p.USB_OTG_FS, irq, p.PA12, p.PA11, &mut ep_out_buffer);
+
+    // Create embassy-usb Config
+    let mut config = embassy_usb::Config::new(0xc0de, 0xcafe);
+    config.manufacturer = Some("Embassy");
+    config.product = Some("USB-serial example");
+    config.serial_number = Some("12345678");
+
+    // Required for windows compatiblity.
+    // https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/kconfig/CONFIG_CDC_ACM_IAD.html#help
+    config.device_class = 0xEF;
+    config.device_sub_class = 0x02;
+    config.device_protocol = 0x01;
+    config.composite_with_iads = true;
+
+    // Create embassy-usb DeviceBuilder using the driver and config.
+    // It needs some buffers for building the descriptors.
+    let mut device_descriptor = [0; 256];
+    let mut config_descriptor = [0; 256];
+    let mut bos_descriptor = [0; 256];
+    let mut control_buf = [0; 64];
+
+    let mut state = State::new();
+
+    let mut builder = Builder::new(
+        driver,
+        config,
+        &mut device_descriptor,
+        &mut config_descriptor,
+        &mut bos_descriptor,
+        &mut control_buf,
+        None,
+    );
+
+    // Create classes on the builder.
+    let mut class = CdcAcmClass::new(&mut builder, &mut state, 64);
+
+    // Build the builder.
+    let mut usb = builder.build();
+
+    // Run the USB device.
+    let usb_fut = usb.run();
+
+    // Do stuff with the class!
+    let echo_fut = async {
+        loop {
+            class.wait_connection().await;
+            info!("Connected");
+            let _ = echo(&mut class).await;
+            info!("Disconnected");
+        }
+    };
+
+    // Run everything concurrently.
+    // If we had made everything `'static` above instead, we could do this using separate tasks instead.
+    join(usb_fut, echo_fut).await;
+}
+
+struct Disconnected {}
+
+impl From<EndpointError> for Disconnected {
+    fn from(val: EndpointError) -> Self {
+        match val {
+            EndpointError::BufferOverflow => panic!("Buffer overflow"),
+            EndpointError::Disabled => Disconnected {},
+        }
+    }
+}
+
+async fn echo<'d, T: Instance + 'd>(class: &mut CdcAcmClass<'d, Driver<'d, T>>) -> Result<(), Disconnected> {
+    let mut buf = [0; 64];
+    loop {
+        let n = class.read_packet(&mut buf).await?;
+        let data = &buf[..n];
+        info!("data: {:x}", data);
+        class.write_packet(data).await?;
+    }
+}
diff --git a/examples/stm32l4/Cargo.toml b/examples/stm32l4/Cargo.toml
index 45d3dd366..5627760ef 100644
--- a/examples/stm32l4/Cargo.toml
+++ b/examples/stm32l4/Cargo.toml
@@ -12,6 +12,7 @@ embassy-executor = { version = "0.1.0", path = "../../embassy-executor", feature
 embassy-time = { version = "0.1.0", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime", "tick-hz-32_768"] }
 embassy-embedded-hal = { version = "0.1.0", path = "../../embassy-embedded-hal" }
 embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "defmt", "unstable-pac", "stm32l4s5vi", "time-driver-any", "exti", "unstable-traits"]  }
+embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt"] }
 
 defmt = "0.3"
 defmt-rtt = "0.4"
@@ -26,6 +27,3 @@ futures = { version = "0.3.17", default-features = false, features = ["async-awa
 heapless = { version = "0.7.5", default-features = false }
 
 micromath = "2.0.0"
-usb-device = "0.2"
-usbd-serial = "0.1.1"
-
diff --git a/examples/stm32l4/src/bin/usb_serial.rs b/examples/stm32l4/src/bin/usb_serial.rs
new file mode 100644
index 000000000..3e38b10a3
--- /dev/null
+++ b/examples/stm32l4/src/bin/usb_serial.rs
@@ -0,0 +1,108 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::{panic, *};
+use defmt_rtt as _; // global logger
+use embassy_executor::Spawner;
+use embassy_stm32::rcc::*;
+use embassy_stm32::usb_otg::{Driver, Instance};
+use embassy_stm32::{interrupt, Config};
+use embassy_usb::class::cdc_acm::{CdcAcmClass, State};
+use embassy_usb::driver::EndpointError;
+use embassy_usb::Builder;
+use futures::future::join;
+use panic_probe as _;
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    info!("Hello World!");
+
+    let mut config = Config::default();
+    config.rcc.mux = ClockSrc::PLL(PLLSource::HSI16, PLLClkDiv::Div2, PLLSrcDiv::Div1, PLLMul::Mul10, None);
+    config.rcc.hsi48 = true;
+
+    let p = embassy_stm32::init(config);
+
+    // Create the driver, from the HAL.
+    let irq = interrupt::take!(OTG_FS);
+    let mut ep_out_buffer = [0u8; 256];
+    let driver = Driver::new_fs(p.USB_OTG_FS, irq, p.PA12, p.PA11, &mut ep_out_buffer);
+
+    // Create embassy-usb Config
+    let mut config = embassy_usb::Config::new(0xc0de, 0xcafe);
+    config.max_packet_size_0 = 64;
+    config.manufacturer = Some("Embassy");
+    config.product = Some("USB-serial example");
+    config.serial_number = Some("12345678");
+
+    // Required for windows compatiblity.
+    // https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/kconfig/CONFIG_CDC_ACM_IAD.html#help
+    config.device_class = 0xEF;
+    config.device_sub_class = 0x02;
+    config.device_protocol = 0x01;
+    config.composite_with_iads = true;
+
+    // Create embassy-usb DeviceBuilder using the driver and config.
+    // It needs some buffers for building the descriptors.
+    let mut device_descriptor = [0; 256];
+    let mut config_descriptor = [0; 256];
+    let mut bos_descriptor = [0; 256];
+    let mut control_buf = [0; 64];
+
+    let mut state = State::new();
+
+    let mut builder = Builder::new(
+        driver,
+        config,
+        &mut device_descriptor,
+        &mut config_descriptor,
+        &mut bos_descriptor,
+        &mut control_buf,
+        None,
+    );
+
+    // Create classes on the builder.
+    let mut class = CdcAcmClass::new(&mut builder, &mut state, 64);
+
+    // Build the builder.
+    let mut usb = builder.build();
+
+    // Run the USB device.
+    let usb_fut = usb.run();
+
+    // Do stuff with the class!
+    let echo_fut = async {
+        loop {
+            class.wait_connection().await;
+            info!("Connected");
+            let _ = echo(&mut class).await;
+            info!("Disconnected");
+        }
+    };
+
+    // Run everything concurrently.
+    // If we had made everything `'static` above instead, we could do this using separate tasks instead.
+    join(usb_fut, echo_fut).await;
+}
+
+struct Disconnected {}
+
+impl From<EndpointError> for Disconnected {
+    fn from(val: EndpointError) -> Self {
+        match val {
+            EndpointError::BufferOverflow => panic!("Buffer overflow"),
+            EndpointError::Disabled => Disconnected {},
+        }
+    }
+}
+
+async fn echo<'d, T: Instance + 'd>(class: &mut CdcAcmClass<'d, Driver<'d, T>>) -> Result<(), Disconnected> {
+    let mut buf = [0; 64];
+    loop {
+        let n = class.read_packet(&mut buf).await?;
+        let data = &buf[..n];
+        info!("data: {:x}", data);
+        class.write_packet(data).await?;
+    }
+}
diff --git a/examples/stm32u5/Cargo.toml b/examples/stm32u5/Cargo.toml
index d88fdda50..2b02eda92 100644
--- a/examples/stm32u5/Cargo.toml
+++ b/examples/stm32u5/Cargo.toml
@@ -9,6 +9,7 @@ embassy-sync = { version = "0.1.0", path = "../../embassy-sync", features = ["de
 embassy-executor = { version = "0.1.0", path = "../../embassy-executor", features = ["defmt", "integrated-timers"] }
 embassy-time = { version = "0.1.0", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime", "tick-hz-32_768"] }
 embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "defmt", "unstable-pac", "stm32u585ai", "time-driver-any", "memory-x" ]  }
+embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt"] }
 
 defmt = "0.3"
 defmt-rtt = "0.4"
diff --git a/examples/stm32u5/src/bin/usb_serial.rs b/examples/stm32u5/src/bin/usb_serial.rs
new file mode 100644
index 000000000..c846836b0
--- /dev/null
+++ b/examples/stm32u5/src/bin/usb_serial.rs
@@ -0,0 +1,108 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::{panic, *};
+use defmt_rtt as _; // global logger
+use embassy_executor::Spawner;
+use embassy_stm32::rcc::*;
+use embassy_stm32::usb_otg::{Driver, Instance};
+use embassy_stm32::{interrupt, Config};
+use embassy_usb::class::cdc_acm::{CdcAcmClass, State};
+use embassy_usb::driver::EndpointError;
+use embassy_usb::Builder;
+use futures::future::join;
+use panic_probe as _;
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    info!("Hello World!");
+
+    let mut config = Config::default();
+    config.rcc.mux = ClockSrc::PLL1R(PllSrc::HSI16, PllM::Div2, PllN::Mul10, PllClkDiv::NotDivided);
+    //config.rcc.mux = ClockSrc::MSI(MSIRange::Range48mhz);
+    config.rcc.hsi48 = true;
+
+    let p = embassy_stm32::init(config);
+
+    // Create the driver, from the HAL.
+    let irq = interrupt::take!(OTG_FS);
+    let mut ep_out_buffer = [0u8; 256];
+    let driver = Driver::new_fs(p.USB_OTG_FS, irq, p.PA12, p.PA11, &mut ep_out_buffer);
+
+    // Create embassy-usb Config
+    let mut config = embassy_usb::Config::new(0xc0de, 0xcafe);
+    config.manufacturer = Some("Embassy");
+    config.product = Some("USB-serial example");
+    config.serial_number = Some("12345678");
+
+    // Required for windows compatiblity.
+    // https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/kconfig/CONFIG_CDC_ACM_IAD.html#help
+    config.device_class = 0xEF;
+    config.device_sub_class = 0x02;
+    config.device_protocol = 0x01;
+    config.composite_with_iads = true;
+
+    // Create embassy-usb DeviceBuilder using the driver and config.
+    // It needs some buffers for building the descriptors.
+    let mut device_descriptor = [0; 256];
+    let mut config_descriptor = [0; 256];
+    let mut bos_descriptor = [0; 256];
+    let mut control_buf = [0; 64];
+
+    let mut state = State::new();
+
+    let mut builder = Builder::new(
+        driver,
+        config,
+        &mut device_descriptor,
+        &mut config_descriptor,
+        &mut bos_descriptor,
+        &mut control_buf,
+        None,
+    );
+
+    // Create classes on the builder.
+    let mut class = CdcAcmClass::new(&mut builder, &mut state, 64);
+
+    // Build the builder.
+    let mut usb = builder.build();
+
+    // Run the USB device.
+    let usb_fut = usb.run();
+
+    // Do stuff with the class!
+    let echo_fut = async {
+        loop {
+            class.wait_connection().await;
+            info!("Connected");
+            let _ = echo(&mut class).await;
+            info!("Disconnected");
+        }
+    };
+
+    // Run everything concurrently.
+    // If we had made everything `'static` above instead, we could do this using separate tasks instead.
+    join(usb_fut, echo_fut).await;
+}
+
+struct Disconnected {}
+
+impl From<EndpointError> for Disconnected {
+    fn from(val: EndpointError) -> Self {
+        match val {
+            EndpointError::BufferOverflow => panic!("Buffer overflow"),
+            EndpointError::Disabled => Disconnected {},
+        }
+    }
+}
+
+async fn echo<'d, T: Instance + 'd>(class: &mut CdcAcmClass<'d, Driver<'d, T>>) -> Result<(), Disconnected> {
+    let mut buf = [0; 64];
+    loop {
+        let n = class.read_packet(&mut buf).await?;
+        let data = &buf[..n];
+        info!("data: {:x}", data);
+        class.write_packet(data).await?;
+    }
+}