Add button example

Author: romancardenas

hifive1-examples/.cargo/config.toml

@@ -1,7 +1,7 @@
 [target.'cfg(all(target_arch = "riscv32", target_os = "none"))']
 runner = "qemu-system-riscv32 -machine sifive_e,revb=true -nographic -semihosting-config enable=on,target=native -kernel" # Uncomment for QEMU
-# runner = "riscv64-unknown-elf-gdb -q -x hifive1-examples/gdb_init" # Uncomment for hardware (no semihosting)
-# runner = "riscv64-unknown-elf-gdb -q -x hifive1-examples/gdb_init_sh" # Uncomment for hardware (semihosting)
+# runner = "riscv64-unknown-elf-gdb -q -x gdb_init" # Uncomment for hardware (no semihosting)
+# runner = "riscv64-unknown-elf-gdb -q -x gdb_init_sh" # Uncomment for hardware (semihosting)
 rustflags = [
     "-C", "link-arg=-Thifive1-link.x",
     "--cfg", "portable_atomic_target_feature=\"zaamo\"",

hifive1-examples/Cargo.toml

@@ -15,6 +15,7 @@ rust-version = "1.72"
 [dependencies]
 critical-section = { version = "1.1.3" }
 hifive1 = { path = "../hifive1", version = "0.13.0", features = ["board-hifive1-revb"] } # Change to your board
+riscv = { version = "0.11.0" }
 riscv-rt = { version = "0.12.2", features = ["single-hart"] }
 panic-halt = "0.2.0"
 semihosting = { version = "0.1",  features = ["stdio", "panic-handler"], optional = true }

hifive1-examples/examples/button_poll.rs

@@ -0,0 +1,54 @@
+//! Example of polling a button and turning on a LED when the button is pressed.
+
+#![no_std]
+#![no_main]
+
+use hifive1::{
+    clock,
+    hal::{delay::Sleep, prelude::*, DeviceResources},
+    pin, sprintln, Led,
+};
+extern crate panic_halt;
+
+#[riscv_rt::entry]
+fn main() -> ! {
+    let dr = DeviceResources::take().unwrap();
+    let p = dr.peripherals;
+    let pins = dr.pins;
+
+    // Configure clocks
+    let clocks = clock::configure(p.PRCI, p.AONCLK, 320.mhz().into());
+
+    // Configure UART for stdout
+    hifive1::stdout::configure(
+        p.UART0,
+        pin!(pins, uart0_tx),
+        pin!(pins, uart0_rx),
+        115_200.bps(),
+        clocks,
+    );
+
+    // Configure button pin as pull-up input
+    let mut button = pins.pin9.into_pull_up_input();
+
+    // get blue LED pin
+    let pin = pin!(pins, led_blue);
+    let mut led = pin.into_inverted_output();
+
+    // Get the sleep struct from CLINT
+    let clint = dr.core_peripherals.clint;
+    let mut sleep = Sleep::new(clint.mtimecmp, clocks);
+
+    const STEP: u32 = 1000; // 1s
+    loop {
+        if button.is_low().unwrap() {
+            sprintln!("Button pressed");
+            led.on();
+        } else {
+            sprintln!("Button released");
+            led.off();
+        }
+        sprintln!("LED is on: {}", led.is_on());
+        sleep.delay_ms(STEP);
+    }
+}

hifive1-examples/examples/hello_world.rs

@@ -31,5 +31,7 @@ fn main() -> ! {
     );
 
     println!("Hello, world!");
-    loop {}
+    loop {
+        riscv::asm::wfi();
+    }
 }

hifive1-examples/examples/led_blink.rs

@@ -29,7 +29,7 @@ fn main() -> ! {
         clocks,
     );
 
-    // get all 3 led pins in a tuple (each pin is it's own type here)
+    // get blue LED pin
     let pin = pin!(pins, led_blue);
     let mut led = pin.into_inverted_output();
 

hifive1/CHANGELOG.md

@@ -6,7 +6,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
-- Add examples based on semihosting
+- Fix Led implementation, as pins are configured as inverted outputs
 - Adapt to embedded-hal 1.0
 - Replace static muts with Mutexes
 - Apply clippy changes

hifive1/src/led.rs

@@ -66,15 +66,15 @@ macro_rules! led_impl {
         $(
             impl Led for $LEDTYPE {
                 fn is_on(&mut self) -> bool {
-                    self.is_set_high().unwrap()
+                    self.is_set_low().unwrap()
                 }
 
                 fn off(&mut self) {
-                    self.set_low().unwrap();
+                    self.set_high().unwrap();
                 }
 
                 fn on(&mut self) {
-                    self.set_high().unwrap();
+                    self.set_low().unwrap();
                 }
             }
         )+