Add RTC example code

Author: timokroeger

examples/rtc-demo/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "rtc-demo"
+version = "0.1.0"
+authors = ["Timo Kröger"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+cortex-m = "0.6.2"
+cortex-m-rt = "0.6.12"
+rtt-target = {version = "0.2.0", features = ["cortex-m"] }
+nrf52840-hal = { features = ["rt"], path = "../../nrf52840-hal" }
+
+[dependencies.embedded-hal]
+version = "0.2.3"
+features = ["unproven"]

examples/rtc-demo/Embed.toml

@@ -0,0 +1,63 @@
+[default.probe]
+# USB vendor ID
+# usb_vid = "1337"
+# USB product ID
+# usb_pid = "1337"
+# Serial number
+# serial = "12345678"
+# The protocol to be used for communicating with the target.
+protocol = "Swd"
+# The speed in kHz of the data link to the target.
+# speed = 1337
+
+[default.flashing]
+# Whether or not the target should be flashed.
+enabled = true
+# Whether or not the target should be halted after reset.
+# DEPRECATED, moved to reset section
+halt_afterwards = false
+# Whether or not bytes erased but not rewritten with data from the ELF
+# should be restored with their contents before erasing.
+restore_unwritten_bytes = false
+# The path where an SVG of the assembled flash layout should be written to.
+# flash_layout_output_path = "out.svg"
+
+[default.reset]
+# Whether or not the target should be reset.
+# When flashing is enabled as well, the target will be reset after flashing.
+enabled = true
+# Whether or not the target should be halted after reset.
+halt_afterwards = false
+
+[default.general]
+# The chip name of the chip to be debugged.
+chip = "nRF52840_xxAA"
+# A list of chip descriptions to be loaded during runtime.
+chip_descriptions = []
+# The default log level to be used. Possible values are one of:
+#   "OFF", "ERROR", "WARN", "INFO", "DEBUG", "TRACE" 
+log_level = "WARN"
+
+[default.rtt]
+# Whether or not an RTTUI should be opened after flashing.
+# This is exclusive and cannot be used with GDB at the moment.
+enabled = true
+# A list of channel associations to be displayed. If left empty, all channels are displayed.
+channels = [
+    # { up = 0, down = 0, name = "name", format = "String" }
+]
+# The duration in ms for which the logger should retry to attach to RTT.
+timeout = 3000
+# Whether timestamps in the RTTUI are enabled
+show_timestamps = true
+# Whether to save rtt history buffer on exit.
+log_enabled = false
+# Where to save rtt history buffer relative to manifest path.
+log_path = "./logs"
+
+[default.gdb]
+# Whether or not a GDB server should be opened after flashing.
+# This is exclusive and cannot be used with RTT at the moment.
+enabled = false
+# The connection string in host:port format wher the GDB server will open a socket.
+# gdb_connection_string

examples/rtc-demo/README.md

@@ -0,0 +1,18 @@
+# RTC demo
+
+This example shows how to use the compare functionality of the real-time counter peripheral.
+Runs on the nRF52840_DK but can easily be adapted for other hardware.
+
+## Set up with `cargo-embed`
+
+Install `cargo-embed` if you don't have it already:
+
+```console
+$ cargo install cargo-embed
+```
+
+Then just `cd` to the example folder and run
+
+```console
+$ cargo embed --target thumbv7em-none-eabihf
+```

examples/rtc-demo/src/main.rs

@@ -0,0 +1,50 @@
+#![no_main]
+#![no_std]
+
+use nrf52840_hal as hal;
+
+use hal::rtc::{Rtc, RtcCompareReg, RtcInterrupt};
+use rtt_target::{rprintln, rtt_init_print};
+
+#[panic_handler] // panicking behavior
+fn panic(_: &core::panic::PanicInfo) -> ! {
+    loop {
+        cortex_m::asm::bkpt();
+    }
+}
+
+#[cortex_m_rt::entry]
+fn main() -> ! {
+    rtt_init_print!();
+
+    let p = hal::pac::Peripherals::take().unwrap();
+
+    // Enable LfClk which is required by the RTC.
+    let clocks = hal::clocks::Clocks::new(p.CLOCK);
+    let clocks = clocks.start_lfclk();
+
+    // Run RTC for 1 second
+    let mut rtc = Rtc::new(p.RTC0);
+    rtc.set_compare(RtcCompareReg::Compare0, 32_768).unwrap();
+    rtc.enable_event(RtcInterrupt::Compare0);
+
+    rprintln!("Starting RTC");
+    let rtc = rtc.enable_counter();
+
+    rprintln!("Waiting for compare match");
+    while !rtc.is_event_triggered(RtcInterrupt::Compare0) {}
+    rtc.reset_event(RtcInterrupt::Compare0);
+
+    rprintln!("Compare match, stopping RTC");
+    let rtc = rtc.disable_counter();
+
+    rprintln!("Counter stopped at {} ticks", rtc.get_counter());
+
+    // Stop LfClk when RTC is not used anymore.
+    rtc.release();
+    clocks.stop_lfclk();
+
+    loop {
+        cortex_m::asm::nop();
+    }
+}

xtask/src/lib.rs

@@ -28,6 +28,7 @@ pub static EXAMPLES: &[(&str, &[&str])] = &[
     ),
     ("pwm-demo", &[]),
     ("qdec-demo", &[]),
+    ("rtc-demo", &[]),
     ("rtic-demo", &["51", "52810", "52811", "52832", "52840"]),
     ("spi-demo", &[]),
     ("spis-demo", &[]),