completed UART HAL, added first example

va416xx-hal/examples/uart.rs

@@ -0,0 +1,48 @@
+//! UART example application. Sends a test string over a UART and then enters
+//! echo mode
+#![no_main]
+#![no_std]
+
+use cortex_m_rt::entry;
+use embedded_io::{Read, Write};
+use panic_rtt_target as _;
+use rtt_target::{rprintln, rtt_init_print};
+use va416xx_hal::time::{Hertz, MegaHertz};
+use va416xx_hal::{gpio::PinsG, pac, uart};
+
+#[entry]
+fn main() -> ! {
+    rtt_init_print!();
+    rprintln!("-- VA416xx UART example application--");
+
+    // SAFETY: Peripherals are only stolen once here.
+    let mut dp = unsafe { pac::Peripherals::steal() };
+
+    let gpiob = PinsG::new(&mut dp.sysconfig, Some(dp.ioconfig), dp.portg);
+    let tx = gpiob.pg0.into_funsel_1();
+    let rx = gpiob.pg1.into_funsel_1();
+
+    let uartb = uart::Uart::uart0(
+        dp.uart0,
+        (tx, rx),
+        Hertz::from_raw(115200),
+        &mut dp.sysconfig,
+        Hertz::from_raw(MegaHertz::from_raw(20).to_Hz()),
+    );
+    let (mut tx, mut rx) = uartb.split();
+    let mut recv_buf: [u8; 32] = [0; 32];
+    writeln!(tx, "Hello World").unwrap();
+    loop {
+        // Echo what is received on the serial link.
+        match rx.read(&mut recv_buf) {
+            Ok(recvd) => {
+                if let Err(e) = tx.write(&recv_buf[0..recvd]) {
+                    rprintln!("UART TX error: {:?}", e);
+                }
+            }
+            Err(e) => {
+                rprintln!("UART RX error {:?}", e);
+            }
+        }
+    }
+}