longan-nano: Add serial example

example-longan-nano-board/Cargo.toml

@@ -7,7 +7,9 @@ edition = "2018"
 [dependencies]
 riscv = "0.6.0"
 riscv-rt = "0.11.0"
+embedded-hal = "0.2.7"
 gd32vf103xx-hal = "0.5.0"
 panic-halt = "0.2.0"
 usb-device = "0.2.9"
+usbd-serial = "0.1.1"
 synopsys-usb-otg = { version = "0.3.2", features = ["riscv", "fs"] }

example-longan-nano-board/examples/serial.rs

@@ -0,0 +1,88 @@
+#![no_std]
+#![no_main]
+
+use panic_halt as _;
+
+use gd32vf103xx_hal::pac;
+use gd32vf103xx_hal::prelude::*;
+use riscv_rt::entry;
+
+use example_longan_nano_board::{UsbBus, USB};
+use usb_device::prelude::*;
+use usbd_serial::{SerialPort, USB_CLASS_CDC};
+
+use embedded_hal::digital::v2::OutputPin;
+
+#[entry]
+fn main() -> ! {
+    let dp = pac::Peripherals::take().unwrap();
+
+    // Configure clocks
+    let mut rcu = dp
+        .RCU
+        .configure()
+        .ext_hf_clock(8.mhz())
+        .sysclk(96.mhz())
+        .freeze();
+
+    assert!(rcu.clocks.usbclk_valid());
+
+    let gpioc = dp.GPIOC.split(&mut rcu);
+    let mut led = gpioc.pc13.into_push_pull_output();
+    led.set_high().unwrap(); // Turn off
+
+    let gpioa = dp.GPIOA.split(&mut rcu);
+    let usb = USB {
+        usb_global: dp.USBFS_GLOBAL,
+        usb_device: dp.USBFS_DEVICE,
+        usb_pwrclk: dp.USBFS_PWRCLK,
+        pin_dm: gpioa.pa11,
+        pin_dp: gpioa.pa12,
+        hclk: rcu.clocks.hclk(),
+    };
+
+    static mut EP_MEMORY: [u32; 1024] = [0; 1024];
+    let usb_bus = UsbBus::new(usb, unsafe { &mut EP_MEMORY });
+
+    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().unwrap(); // 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().unwrap(); // Turn off
+    }
+}