Initial Commit with polling

.cargo/config

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+[target.thumbv7m-none-eabi]
+runner = "arm-none-eabi-gdb -q -x openocd.gdb"
+rustflags = [
+  "-C", "linker=rust-lld",
+  "-C", "link-arg=-Tlink.x",
+]
+
+[build]
+target = "thumbv7m-none-eabi"

.gitignore

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+target/
+Cargo.lock
+
+.gdb_history

Cargo.toml

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+[package]
+name = "stm32-usbd-usart"
+version = "0.1.0"
+authors = ["Sebastian Schumb <sebastian@sebastians-site.de>"]
+edition = "2018"
+
+[dependencies]
+cortex-m = "0.6"
+cortex-m-rt = "0.6"
+stm32f1xx-hal = { version = "0.5", features = ["stm32f103", "stm32-usbd", "rt"] }
+panic-semihosting = "0.5"
+usb-device = "0.2.4"
+usbd-serial = "0.1"
+embedded-hal = "0.2.3"

build.rs

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+use std::env;
+use std::fs;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put the linker script somewhere the linker can find it
+    let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
+    fs::File::create(out_dir.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out_dir.display());
+    println!("cargo:rerun-if-changed=memory.x");
+}

memory.x

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+/* STM32F103C8T6 */
+MEMORY
+{
+    FLASH : ORIGIN = 0x08000000, LENGTH = 64K
+    RAM   : ORIGIN = 0x20000000, LENGTH = 20K
+}

openocd.gdb

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+set history save on
+set confirm off
+target extended-remote :3333
+set print asm-demangle on
+monitor arm semihosting enable
+monitor reset halt
+load
+# monitor verify
+# monitor reset
+# quit
+continue

openocd.sh

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+#!/bin/bash
+openocd -f interface/stlink-v2.cfg -f target/stm32f1x.cfg

src/main.rs

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+#![no_std]
+#![no_main]
+
+extern crate panic_semihosting;
+
+use cortex_m::asm::delay;
+use cortex_m_rt::entry;
+use embedded_hal::digital::v2::OutputPin;
+use stm32f1xx_hal::usb::{Peripheral, UsbBus};
+use stm32f1xx_hal::{prelude::*, stm32};
+use usb_device::prelude::*;
+use usbd_serial::{SerialPort, USB_CLASS_CDC};
+
+#[entry]
+fn main() -> ! {
+    let dp = stm32::Peripherals::take().unwrap();
+
+    let mut flash = dp.FLASH.constrain();
+    let mut rcc = dp.RCC.constrain();
+
+    let clocks = rcc
+        .cfgr
+        .use_hse(8.mhz())
+        .sysclk(48.mhz())
+        .pclk1(24.mhz())
+        .freeze(&mut flash.acr);
+
+    assert!(clocks.usbclk_valid());
+
+    // Configure the on-board LED (PC13, green)
+    let mut gpioc = dp.GPIOC.split(&mut rcc.apb2);
+    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
+    led.set_high().ok(); // Turn off
+
+    let mut gpioa = dp.GPIOA.split(&mut rcc.apb2);
+
+    // 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 mut usb_dp = gpioa.pa12.into_push_pull_output(&mut gpioa.crh);
+    usb_dp.set_low().ok();
+    delay(clocks.sysclk().0 / 100);
+
+    let usb = Peripheral {
+        usb: dp.USB,
+        pin_dm: gpioa.pa11,
+        pin_dp: usb_dp.into_floating_input(&mut gpioa.crh),
+    };
+    let usb_bus = UsbBus::new(usb);
+
+    let mut serial = SerialPort::new(&usb_bus);
+
+    let mut usb_dev = UsbDeviceBuilder::new(&usb_bus, UsbVidPid(0x16c0, 0x27dd))
+        .manufacturer("Fake company")
+        .product("Serial port")
+        .serial_number("TEST")
+        .device_class(USB_CLASS_CDC)
+        .build();
+
+    loop {
+        if !usb_dev.poll(&mut [&mut serial]) {
+            continue;
+        }
+
+        let mut buf = [0u8; 64];
+
+        match serial.read(&mut buf) {
+            Ok(count) if count > 0 => {
+                led.set_low().ok(); // Turn on
+
+                // Echo back in upper case
+                for c in buf[0..count].iter_mut() {
+                    if 0x61 <= *c && *c <= 0x7a {
+                        *c &= !0x20;
+                    }
+                }
+
+                let mut write_offset = 0;
+                while write_offset < count {
+                    match serial.write(&buf[write_offset..count]) {
+                        Ok(len) if len > 0 => {
+                            write_offset += len;
+                        }
+                        _ => {}
+                    }
+                }
+            }
+            _ => {}
+        }
+
+        led.set_high().ok(); // Turn off
+    }
+}