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add a safe method to software unlock the DWT #173

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Oct 16, 2019
Merged

add a safe method to software unlock the DWT #173

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9 changes: 9 additions & 0 deletions src/peripheral/dwt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -75,4 +75,13 @@ impl DWT {
// NOTE(unsafe) atomic read with no side effects
unsafe { (*Self::ptr()).cyccnt.read() }
}

/// Removes the software lock on the DWT
///
/// Some devices, like the STM32F7, software lock the DWT after a power cycle.
#[cfg(not(armv6m))]
pub fn unlock() {
// NOTE(unsafe) atomic write to a stateless, write-only register
unsafe { (*Self::ptr()).lar.write(0xC5ACCE55) }
}
}