refine panic handler and add some logging info

CHANGELOG.md

@@ -16,7 +16,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 * Const generics, bumping the MSRV to 1.51.0
 * `lockin-internal` and `lockin-external` have been merged into `lockin`
-* Default target CPU is cortex-m7, effective bumping the MSRV to 1.52.0
+* Set target CPU to cortex-m7, effectively bumping the MSRV to 1.52.0
 
 ### Fixed
 

README.md

@@ -10,7 +10,7 @@
 
 ## Applications
 
-This firmware offers a library of hardware and software functionality targeting the use of the Stabilizer hardware in various digital signal processing applications commonly occurring in Quantum Technology applications.
+This firmware offers a library of hardware and software functionality targeting the use of the Stabilizer hardware in various digital signal processing applications commonly occurring in Quantum Technology.
 It provides abstractions over the fast analog inputs and outputs, time stamping, Pounder DDS interfaces and a collection of tailored and optimized digital signal processing algorithms (IIR, FIR, Lockin, PLL, reciprocal PLL, Unwrapper, Lowpass, Cosine-Sine, Atan2).
 An application can compose and configure these hardware and software components to implement different use cases.
 Several applications are provides by default:

src/hardware/configuration.rs

@@ -157,7 +157,7 @@ pub fn setup(
         log::set_logger(&LOGGER)
             .map(|()| log::set_max_level(log::LevelFilter::Trace))
             .unwrap();
-        log::info!("Starting...");
+        log::info!("starting...");
     }
 
     // Set up the system timer for RTIC scheduling.
@@ -537,6 +537,7 @@ pub fn setup(
         &mut eeprom_i2c,
         &mut delay,
     ));
+    log::info!("EUI48: {}", mac_addr);
 
     let network_devices = {
         // Configure the ethernet controller
@@ -673,6 +674,7 @@ pub fn setup(
     let pounder_pgood = gpiob.pb13.into_pull_down_input();
     delay.delay_ms(2u8);
     let pounder = if pounder_pgood.is_high().unwrap() {
+        log::info!("Found Pounder");
         let ad9959 = {
             let qspi_interface = {
                 // Instantiate the QUADSPI pins and peripheral interface.
@@ -935,6 +937,7 @@ pub fn setup(
     // info!("Version {} {}", build_info::PKG_VERSION, build_info::GIT_VERSION.unwrap());
     // info!("Built on {}", build_info::BUILT_TIME_UTC);
     // info!("{} {}", build_info::RUSTC_VERSION, build_info::TARGET);
+    log::info!("setup() complete");
 
     // Enable the instruction cache.
     core.SCB.enable_icache();

src/hardware/mod.rs

@@ -59,15 +59,22 @@ pub use configuration::{setup, PounderDevices, StabilizerDevices};
 fn panic(info: &core::panic::PanicInfo) -> ! {
     use core::{
         fmt::Write,
-        sync::atomic::{compiler_fence, Ordering::SeqCst},
+        sync::atomic::{AtomicBool, Ordering},
     };
-    use cortex_m::interrupt;
+    use cortex_m::asm;
     use rtt_target::{ChannelMode, UpChannel};
 
-    interrupt::disable();
+    cortex_m::interrupt::disable();
+
+    // Recursion protection
+    static PANICKED: AtomicBool = AtomicBool::new(false);
+    while PANICKED.load(Ordering::Relaxed) {
+        asm::bkpt();
+    }
+    PANICKED.store(true, Ordering::Relaxed);
 
-    let gpiod = unsafe { &*hal::stm32::GPIOD::ptr() };
     // Turn on both red LEDs, FP_LED_1, FP_LED_3
+    let gpiod = unsafe { &*hal::stm32::GPIOD::ptr() };
     gpiod.odr.modify(|_, w| w.odr6().high().odr12().high());
 
     // Analogous to panic-rtt-target
@@ -76,10 +83,10 @@ fn panic(info: &core::panic::PanicInfo) -> ! {
         writeln!(channel, "{}", info).ok();
     }
 
-    loop {
-        // Halt
-        compiler_fence(SeqCst);
-    }
+    // Abort
+    asm::udf();
+    // Halt
+    // loop { core::sync::atomic::compiler_fence(Ordering::SeqCst); }
 }
 
 #[cortex_m_rt::exception]