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Discussion Groups | 68HC12 | Re: How to use HC12's ECT as a general purpose Timer?
Join our technical discussions about Freescale Microcontrollers: M68HC12. (Freescale Semiconductor is a Subsidiary of Motorola).
Re: How to use HC12's ECT as a general purpose Timer? - Michael Elphick - May 18 6:56:00 2005
Amr,
From the expression 'general purpose timer', it is
is difficult to know what it is you are after.
The RTI can operate several timers, but what
period and resolution do you require? Are you
timing external events etc.?
Mike.
> OK Mike, but will this provide eight different channels?
>
> Amr
> --- In 68HC12@68HC..., "Michael Elphick" <mike.elphick@d...>
> wrote:
>>
>> On Wednesday, May 18, 2005 9:27 AM (BST),
>> "Amr M. Adel" <amradel_79@h...> wrote: -
>>
>>
>> > Hi all,
>> > I am a new member in this group. I hope to gain new knowledge and
>> > share my konwledge with you.
>> >
>> > I need to implement a general purpose timer on HC12
> microcontroller
>> > and as U know it is not provided in HC12. ECT, Enhanced Capture
>> > Timer, is the only thing that can be used for this purpose.
>> >
>> > I have an idea to use ECT as a General Purpose Timer. This can be
>> > achieved by changing the value of the comparator of a channel each
>> > time a it finishs its period. The main disadvantage of this
> technique
>> > is that periods may be irrigular because of the adjustement of the
>> > comparator is depending on ISR which may ba masked or delayed!
>> >
>> > Any Suggestion or documentation describing how to achieve this?
>> >
>> > Thanx for your interest,
>> > Amr
>>
>> Why not use the Real Time Interrupt (RTI), which is part of the
> Clock
>> and Reset Generator (CRG)? This is derived from OSCCLK via a
>> divisor register. To get this to work with a seconds time-base you
> may
>> need a non-standard crystal frequency or an adjustment in your
>> interrupt routine.
>>
>> Mike. >
>
> Yahoo! Groups Links
______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )
From the expression 'general purpose timer', it is
is difficult to know what it is you are after.
The RTI can operate several timers, but what
period and resolution do you require? Are you
timing external events etc.?
Mike.
> OK Mike, but will this provide eight different channels?
>
> Amr
> --- In 68HC12@68HC..., "Michael Elphick" <mike.elphick@d...>
> wrote:
>>
>> On Wednesday, May 18, 2005 9:27 AM (BST),
>> "Amr M. Adel" <amradel_79@h...> wrote: -
>>
>>
>> > Hi all,
>> > I am a new member in this group. I hope to gain new knowledge and
>> > share my konwledge with you.
>> >
>> > I need to implement a general purpose timer on HC12
> microcontroller
>> > and as U know it is not provided in HC12. ECT, Enhanced Capture
>> > Timer, is the only thing that can be used for this purpose.
>> >
>> > I have an idea to use ECT as a General Purpose Timer. This can be
>> > achieved by changing the value of the comparator of a channel each
>> > time a it finishs its period. The main disadvantage of this
> technique
>> > is that periods may be irrigular because of the adjustement of the
>> > comparator is depending on ISR which may ba masked or delayed!
>> >
>> > Any Suggestion or documentation describing how to achieve this?
>> >
>> > Thanx for your interest,
>> > Amr
>>
>> Why not use the Real Time Interrupt (RTI), which is part of the
> Clock
>> and Reset Generator (CRG)? This is derived from OSCCLK via a
>> divisor register. To get this to work with a seconds time-base you
> may
>> need a non-standard crystal frequency or an adjustment in your
>> interrupt routine.
>>
>> Mike. >
>
> Yahoo! Groups Links
______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.
(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )