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setup_timer_2( )

 
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samuel yap



Joined: 15 Feb 2012
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setup_timer_2( )
PostPosted: Fri Feb 17, 2012 10:33 am     Reply with quote
Who can explain ?


Quote:
setup_timer_2 ( T2_DIV_BY_4, 0xc0, 2);

// At 20Mhz, the timer will increment every 800ns,

// will overflow every 154.4us,

// and will interrupt every 308.8us.


1. How to get the value of 800ns, 154.4us, and 308.8us ?
2. 20MHz oscillator means what? What is the use to have oscillator?
Lemosek



Joined: 15 Oct 2011
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PostPosted: Fri Feb 17, 2012 11:46 am     Reply with quote
Hello,
At this link:
http://www.ccsinfo.com/forum/viewtopic.php?t=44557&highlight=timer2
Mr. Ttelmah explain how to set timer2.

Best regards
R.L.
samuel yap



Joined: 15 Feb 2012
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PostPosted: Mon Feb 20, 2012 1:05 am     Reply with quote
He only explain about 154.4us, what about 800ns and 308.8us ?
Ttelmah



Joined: 11 Mar 2010
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PostPosted: Mon Feb 20, 2012 6:01 am     Reply with quote
Look again.
Think for a moment. Master clock/(4*prescaler), gives a clock rate of 1.25MHz feeding the counter. What is 1/1.25E6?
Then what is 154.4*2. Given the last number says 'how many times the timer must loop between interrupts', what do you think this implies?....

Best Wishes
samuel yap



Joined: 15 Feb 2012
Posts: 11

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PostPosted: Mon Feb 20, 2012 7:31 am     Reply with quote
Ttelmah wrote:
Look again.
Think for a moment. Master clock/(4*prescaler), gives a clock rate of 1.25MHz feeding the counter. What is 1/1.25E6?
Then what is 154.4*2. Given the last number says 'how many times the timer must loop between interrupts', what do you think this implies?....

Best Wishes


thx, very clear. may i know what is mean by overflow ?
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