Asymmetric Single Pulse Timer

Asymmetric Single Pulse Timer

The Asymmetric Single Pulse Timer produces a signal consisting of one highstate semiperiod and one lowstate semiperiod or one lowstate semiperiod and one highstate semiperiod. At the end of the first semiperiod, it raises an AsymmetricSinglePulseTimerSemiperiodExpired flag and at the end of the second semiperiod it raises AsymmetricSinglePulseTimerExpired flag.

This timer can be used to make easier to implement some logic constructions, where a time interval should start after an initial delay or AsymmetricSinglePulseTimerExpired should be raised after some delay after the time interval has finished. These tasks can be solved using regular Single Shot timers however they require additional logic from the application.

The two variants of the output are:

         +--------+
  first  | second |
+--------+        +
         ^ AsymmetricSinglePulseTimerSemiperiodExpired(tag) raised here

or

+--------+
| first  | second
+        +--------+
                  ^ AsymmetricSinglePulseTimerExpired(tag) raised here

Declaration.

Macro	Description
DEFINE_ASYMMETRIC_SINGLE_PULSE_TIMER(tag,ttype)	Declare a ASPT timer in .c file by decalring its variables. tag is the tag of the timer, and ttype is its type.
EXTERN_ASYMMETRIC_SINGLE_PULSE_TIMER(tag,ttype)	Define external definitions in .h file. tag is the tag of the timer, and ttype is its type.

Variables.

Variable	Description
AsymmetricSinglePulseTimerSettingFirst(tag)	Setting of the first semiperiod. It can be used as lvalue.
AsymmetricSinglePulseTimerSettingSecond(tag)	Setting of the second semiperiod. It can be used as lvalue.
AsymmetricSinglePulseTimerCounter(tag)	Counter of the timer. It is not good idea to access this avriable directly.
AsymmetricSinglePulseTimerFlag(tag)	This flag, when true, indicates active, working timer. When false the flag indicates a stopped timer.
AsymmetricSinglePulseTimerSemiperiod(tag)	This variable indicates which semiperiod is measured at the moment. false means first and true means second one.
AsymmetricSinglePulseTimerState(tag)	This variable holds the state of the timer output - lowstate or highstate.
AsymmetricSinglePulseTimerSemiperiodExpired(tag)	This flag is raised when the first semiperiod has expired.
AsymmetricSinglePulseTimerExpired(tag)	This flag is raised when the second semiperiod has expired.

Manipulation macros.

Macro	Description
SetAsymmetricSinglePulseTimer(tag,first,second,istate)	This macro starts a timer with tag tag. The arguments first and second are the times for the first and second interval. istate is the initial state - lowstate or highstate. It is possible one of the two times to be zero. Then this timer acts similarly to the Single Pulse timers. If first is zero, then AsymmetricSinglePulseTimerSemiperiodExpired(tag) is raised and AsymmetricSinglePulseTimerState(tag) is set to !istate. The macro disables the interrupts and enables them at the end.
SetAsymmetricSinglePulseTimerI(tag,first,second,istate)	This macro starts a timer with tag tag. The arguments first and second are the times for the first and second interval. istate is the initial state - ASPT_STATE_HIGH or ASPT_STATE_LOW. It is possible one of the two times to be zero. Then this timer acts similarly to the Single Pulse timers. If first is zero, then AsymmetricSinglePulseTimerSemiperiodExpired(tag) is raised and AsymmetricSinglePulseTimerState(tag) is set to !istate. The macro does not touch the interrupts and thus it is convenient to be used with previously disabled interrupts.
StopAsymmetricSinglePulseTimer(tag)	This macro stops a timer with tag tag. It clears AsymmetricSinglePulseTimerState(tag), AsymmetricSinglePulseTimerSemiperiodExpired(tag) and AsymmetricSinglePulseTimerExpired(tag)'. Also, it sets AsymmetricSinglePulseTimerState(tag)toASPT_STATE_LOWandAsymmetricSinglePulseTimerSemiperiod(tag)tofalse`. This macro disables the interrupts and enables them at the end.
ResetAsymmetricSinglePulseTimer(tag)	This macro stops a timer with tag tag. It clears AsymmetricSinglePulseTimerState(tag), AsymmetricSinglePulseTimerSemiperiodExpired(tag) and AsymmetricSinglePulseTimerExpired(tag)'. Also, it sets AsymmetricSinglePulseTimerState(tag)toASPT_STATE_LOWandAsymmetricSinglePulseTimerSemiperiod(tag)tofalse`. The macro does not touch the interrupts and thus it is convenient to be used with previously disabled interrupts.
ClearAsymmetricSinglePulseTimer(tag)	This macro clears all variable of the timer. The macro does not touch the interrupts and thus it is convenient to be used with previously disabled interrupts.
TickAsymmetricSinglePulseTimer(tag)	This macro decrements by one AsymmetricSinglePulseTimerCounter(tag). When the counter becomes zero, the current semiriod is finished. If this was the first semiperiod, AsymmetricSinglePulseTimerSemiperiodExpired(tag) is raised and the counter is loaded it AsymmetricSinglePulseTimerSettingSecond(tag). If the second period has finised, then AsymmetricSinglePulseTimerExpired(tag) is raised and the timer is stopped by clearing StopAsymmetricSinglePulseTimer(tag).