diff options
Diffstat (limited to 'src/peripheral/syst.rs')
| -rw-r--r-- | src/peripheral/syst.rs | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/src/peripheral/syst.rs b/src/peripheral/syst.rs index e02275d..ddffcde 100644 --- a/src/peripheral/syst.rs +++ b/src/peripheral/syst.rs @@ -39,8 +39,7 @@ const SYST_CALIB_NOREF: u32 = 1 << 31; impl SYST { /// Clears current value to 0 /// - /// After calling `clear_current()`, the next call to `has_wrapped()` - /// will return `false`. + /// After calling `clear_current()`, the next call to `has_wrapped()` will return `false`. pub fn clear_current(&mut self) { unsafe { self.cvr.write(0) } } @@ -56,6 +55,17 @@ impl SYST { } /// Enables counter + /// + /// *NOTE* The reference manual indicates that: + /// + /// "The SysTick counter reload and current value are undefined at reset, the correct + /// initialization sequence for the SysTick counter is: + /// + /// - Program reload value + /// - Clear current value + /// - Program Control and Status register" + /// + /// The sequence translates to `self.set_reload(x); self.clear_current(); self.enable_counter()` pub fn enable_counter(&mut self) { unsafe { self.csr.modify(|v| v | SYST_CSR_ENABLE) } } @@ -153,6 +163,8 @@ impl SYST { /// Sets reload value /// /// Valid values are between `1` and `0x00ffffff`. + /// + /// *NOTE* To make the timer wrap every `N` ticks set the reload value to `N - 1` pub fn set_reload(&mut self, value: u32) { unsafe { self.rvr.write(value) } } |