Add basic examples

examples/serial.rs

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+//! Serial interface echo server example
+//!
+//! In this example every received byte will be sent back to the sender. You can test this
+//! example with serial terminal emulator like `minicom`.
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_rt::entry;
+//use cortex_m_semihosting::hprintln;
+use hal::block;
+use hal::prelude::*;
+use hal::serial::{config::Config as SerialConfig, Serial};
+
+#[entry]
+fn main() -> ! {
+    let device = hal::stm32::Peripherals::take().unwrap();
+
+    let rcc = device.RCC.constrain();
+    let clocks = rcc.cfgr.sysclk(48.mhz()).freeze();
+
+    let gpioa = device.GPIOA.split();
+    let tx = gpioa.pa2.into_alternate_af7();
+    let rx = gpioa.pa3.into_alternate_af7();
+    let config = SerialConfig::default().baudrate(9_600.bps());
+
+    let serial = Serial::usart2(device.USART2, (tx, rx), config, clocks).unwrap();
+    let (mut tx, mut rx) = serial.split();
+
+    loop {
+        let byte = block!(rx.read()).unwrap();
+        //hprintln!("in: {}", byte).unwrap();
+        block!(tx.write(byte)).ok();
+    }
+}

examples/spi.rs

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+//! Accelerometer via SPI example
+//!
+//! This example reads all axes from the accelerometer and outputs it via semihosting
+//! debug output.
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_rt::entry;
+use cortex_m_semihosting::hprintln;
+//use hal::block;
+use hal::prelude::*;
+use hal::spi::{Mode, Phase, Polarity, Spi};
+
+#[entry]
+fn main() -> ! {
+    let device = hal::stm32::Peripherals::take().unwrap();
+
+    let rcc = device.RCC.constrain();
+    let clocks = rcc.cfgr.freeze();
+
+    let gpioa = device.GPIOA.split();
+    let sck = gpioa.pa5.into_alternate_af5();
+    let miso = gpioa.pa6.into_alternate_af5();
+    let mosi = gpioa.pa7.into_alternate_af5();
+    let mode = Mode {
+        polarity: Polarity::IdleHigh,
+        phase: Phase::CaptureOnSecondTransition,
+    };
+    let mut spi = Spi::spi1(device.SPI1, (sck, miso, mosi), mode, 100.hz(), clocks);
+
+    let gpioe = device.GPIOE.split();
+    let mut cs = gpioe.pe3.into_push_pull_output();
+
+    // Init
+    cs.set_low();
+    let mut commands = [0x20, 0b01000111];
+    let _ = spi.transfer(&mut commands[..]).unwrap();
+    cs.set_high();
+
+    loop {
+        // Read
+        cs.set_low();
+        let mut commands = [(1 << 7) | (1 << 6) | 0x29, 0x0, 0x0, 0x0, 0x0, 0x0];
+        let result = spi.transfer(&mut commands[..]).unwrap();
+        let acc_x = result[1] as i8;
+        let acc_y = result[3] as i8;
+        let acc_z = result[5] as i8;
+        cs.set_high();
+        hprintln!("{}, {}, {}", acc_x, acc_y, acc_z).unwrap();
+    }
+}