stm32: add USB driver.

examples/stm32f1/Cargo.toml

@@ -8,6 +8,8 @@ resolver = "2"
 [dependencies]
 embassy = { version = "0.1.0", path = "../../embassy", features = ["defmt", "defmt-timestamp-uptime", "time-tick-32768hz"] }
 embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "defmt", "stm32f103c8", "unstable-pac", "memory-x", "time-driver-any"]  }
+embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt"] }
+embassy-usb-serial = { version = "0.1.0", path = "../../embassy-usb-serial", features = ["defmt"] }
 
 defmt = "0.3"
 defmt-rtt = "0.3"

examples/stm32f1/src/bin/usb_serial.rs

@@ -0,0 +1,117 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::panic;
+use defmt::*;
+use defmt_rtt as _; // global logger
+use embassy::executor::Spawner;
+use embassy::time::Duration;
+use embassy::time::Timer;
+use embassy_stm32::gpio::Level;
+use embassy_stm32::gpio::Output;
+use embassy_stm32::gpio::Speed;
+use embassy_stm32::interrupt;
+use embassy_stm32::time::Hertz;
+use embassy_stm32::usb::{Driver, Instance};
+use embassy_stm32::{Config, Peripherals};
+use embassy_usb::driver::EndpointError;
+use embassy_usb::Builder;
+use embassy_usb_serial::{CdcAcmClass, State};
+use futures::future::join;
+use panic_probe as _;
+
+fn config() -> Config {
+    let mut config = Config::default();
+    config.rcc.hse = Some(Hertz(8_000_000));
+    config.rcc.sys_ck = Some(Hertz(48_000_000));
+    config.rcc.pclk1 = Some(Hertz(24_000_000));
+    config
+}
+
+#[embassy::main(config = "config()")]
+async fn main(_spawner: Spawner, mut p: Peripherals) {
+    info!("Hello World!");
+
+    {
+        // BluePill board has a pull-up resistor on the D+ line.
+        // Pull the D+ pin down to send a RESET condition to the USB bus.
+        // This forced reset is needed only for development, without it host
+        // will not reset your device when you upload new firmware.
+        let _dp = Output::new(&mut p.PA12, Level::Low, Speed::Low);
+        Timer::after(Duration::from_millis(10)).await;
+    }
+
+    // Create the driver, from the HAL.
+    let irq = interrupt::take!(USB_LP_CAN1_RX0);
+    let driver = Driver::new(p.USB, irq, p.PA12, p.PA11);
+
+    // Create embassy-usb Config
+    let config = embassy_usb::Config::new(0xc0de, 0xcafe);
+    //config.max_packet_size_0 = 64;
+
+    // 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; 7];
+
+    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?;
+    }
+}