usb_serial_rtic.rs

//! CDC-ACM serial port example using cortex-m-rtic.
//! Target board: Blue Pill
#![no_main]
#![no_std]
#![allow(non_snake_case)]
#![deny(unsafe_code)]

use panic_semihosting as _;

#[rtic::app(device = stm32f1xx_hal::pac)]
mod app {
    use cortex_m::asm::delay;
    use stm32f1xx_hal::prelude::*;
    use stm32f1xx_hal::usb::{Peripheral, UsbBus, UsbBusType};
    use usb_device::prelude::*;

    #[shared]
    struct Shared {
        usb_dev: UsbDevice<'static, UsbBusType>,
        serial: usbd_serial::SerialPort<'static, UsbBusType>,
    }

    #[local]
    struct Local {}

    #[init(local = [usb_bus: Option<usb_device::bus::UsbBusAllocator<UsbBusType>> = None])]
    fn init(cx: init::Context) -> (Shared, Local, init::Monotonics) {
        let mut flash = cx.device.FLASH.constrain();
        let rcc = cx.device.RCC.constrain();

        let clocks = rcc
            .cfgr
            .use_hse(8.MHz())
            .sysclk(48.MHz())
            .pclk1(24.MHz())
            .freeze(&mut flash.acr);

        assert!(clocks.usbclk_valid());

        let mut gpioa = cx.device.GPIOA.split();

        // 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();
        delay(clocks.sysclk().raw() / 100);

        let usb_dm = gpioa.pa11;
        let usb_dp = usb_dp.into_floating_input(&mut gpioa.crh);

        let usb = Peripheral {
            usb: cx.device.USB,
            pin_dm: usb_dm,
            pin_dp: usb_dp,
        };

        cx.local.usb_bus.replace(UsbBus::new(usb));
        let usb_bus = cx.local.usb_bus.as_ref().unwrap();

        let serial = usbd_serial::SerialPort::new(usb_bus);
        let usb_dev = UsbDeviceBuilder::new(usb_bus, UsbVidPid(0x16c0, 0x27dd))
            .device_class(usbd_serial::USB_CLASS_CDC)
            .strings(&[StringDescriptors::default()
                .manufacturer("Fake Company")
                .product("Serial port")
                .serial_number("TEST")])
            .unwrap()
            .build();

        (Shared { usb_dev, serial }, Local {}, init::Monotonics())
    }

    #[task(binds = USB_HP_CAN_TX, shared = [usb_dev, serial])]
    fn usb_tx(cx: usb_tx::Context) {
        let mut usb_dev = cx.shared.usb_dev;
        let mut serial = cx.shared.serial;

        (&mut usb_dev, &mut serial).lock(|usb_dev, serial| {
            super::usb_poll(usb_dev, serial);
        });
    }

    #[task(binds = USB_LP_CAN_RX0, shared = [usb_dev, serial])]
    fn usb_rx0(cx: usb_rx0::Context) {
        let mut usb_dev = cx.shared.usb_dev;
        let mut serial = cx.shared.serial;

        (&mut usb_dev, &mut serial).lock(|usb_dev, serial| {
            super::usb_poll(usb_dev, serial);
        });
    }
}

fn usb_poll<B: usb_device::bus::UsbBus>(
    usb_dev: &mut usb_device::prelude::UsbDevice<'static, B>,
    serial: &mut usbd_serial::SerialPort<'static, B>,
) {
    if !usb_dev.poll(&mut [serial]) {
        return;
    }

    let mut buf = [0u8; 8];

    match serial.read(&mut buf) {
        Ok(count) if count > 0 => {
            // Echo back in upper case
            for c in buf[0..count].iter_mut() {
                if 0x61 <= *c && *c <= 0x7a {
                    *c &= !0x20;
                }
            }

            serial.write(&buf[0..count]).ok();
        }
        _ => {}
    }
}