From 60639b3a9ca22b89067124651ff86ab3c81756c1 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge@japaric.io>
Date: Tue, 21 Jan 2020 22:13:23 +0100
Subject: use the safe DWT::unlock API

instead of a unsafe write_volatile call
---
 examples/schedule.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'examples')

diff --git a/examples/schedule.rs b/examples/schedule.rs
index 97818e3..8dbe4ab 100644
--- a/examples/schedule.rs
+++ b/examples/schedule.rs
@@ -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`
-- 
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