Crate ep_dwt

EmbeddedProfiler implementation based on DWT.

This profiler depends on the DWT hardware which is not available on cortex-M0. The profiler’s resolution is the same as the core clock. The cycle count clock is free-running, so overflows are likely if you have long running functions to profile. To mitigate this, one can use the extended feature, which extends the resolution of the counter from u32 to u64 using the DebugMonitor exception. It is set to expire just before overflow, so you can expect an exception to fire every 2**32 clock cycles.

Snapshots are logged using log::info!, so having a logger installed is required if you want to use embedded_profiling::log_snapshot or functions that call it (like embedded_profiling::profile_function).

Example Usage

 let mut core = CorePeripherals::take().unwrap();
 // (...)
 let dwt_profiler = cortex_m::singleton!(: ep_dwt::DwtProfiler::<CORE_FREQ> =
     ep_dwt::DwtProfiler::<CORE_FREQ>::new(&mut core.DCB, core.DWT, CORE_FREQ))
 .unwrap();
 unsafe {
     embedded_profiling::set_profiler(dwt_profiler).unwrap();
 }
 // (...)
 embedded_profiling::profile("print_profile", || println!("Hello, world"));

Features

extended

Extends the DWT cycle counter’s native resolution from 32 bit to 64 bit using the cycle compare functionality and the DebugMonitor exception. The exception will fire every 2**32 clock cycles. Enables the embedded-profiling feature container-u64.

proc-macros

enables the proc-macros feature in embedded-profiling. Enables the embedded_profiling::profile_function procedural macro.

Structs

DwtProfiler

DWT trace unit implementing EmbeddedProfiler.