294: use the safe DWT::unlock API r=korken89 a=japaric

instead of a unsafe write_volatile call

Co-authored-by: Jorge Aparicio <jorge@japaric.io>
This commit is contained in:
bors[bot] 2020-01-24 15:45:14 +00:00 committed by GitHub
commit 60c14ef680
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2 changed files with 5 additions and 3 deletions

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@ -47,7 +47,7 @@ name = "types"
required-features = ["__v7"]
[dependencies]
cortex-m = "0.6.0"
cortex-m = "0.6.2"
cortex-m-rtfm-macros = { path = "macros", version = "0.5.0" }
rtfm-core = "0.3.0"
cortex-m-rt = "0.6.9"

View file

@ -1,9 +1,11 @@
//! examples/schedule.rs
#![deny(unsafe_code)]
#![deny(warnings)]
#![no_main]
#![no_std]
use cortex_m::peripheral::DWT;
use cortex_m_semihosting::hprintln;
use panic_halt as _;
use rtfm::cyccnt::{Instant, U32Ext as _};
@ -15,8 +17,8 @@ const APP: () = {
fn init(mut cx: init::Context) {
// Initialize (enable) the monotonic timer (CYCCNT)
cx.core.DCB.enable_trace();
// required on devices that software lock the DWT (e.g. STM32F7)
unsafe { cx.core.DWT.lar.write(0xC5ACCE55) }
// required on Cortex-M7 devices that software lock the DWT (e.g. STM32F7)
DWT::unlock();
cx.core.DWT.enable_cycle_counter();
// semantically, the monotonic timer is frozen at time "zero" during `init`