2008-12-01 12:33:09     gptimer questions...

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2008-12-01 12:33:09     gptimer questions...

John Doe (UNITED STATES)

Message: 66098   

 

what is the finest resolution that i can get with /dev/timer[0-7] ?

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2008-12-01 13:32:53     Re: gptimer questions...

Robin Getz (UNITED STATES)

Message: 66101   

 

Dustin:

 

You can get 1/SCLK.

 

-Robin

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2008-12-01 13:43:01     Re: gptimer questions...

John Doe (UNITED STATES)

Message: 66103   

 

how can i find out what my sysclock is exactly or to set it myself?

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2008-12-01 14:02:48     Re: gptimer questions...

Mike Frysinger (UNITED STATES)

Message: 66107   

 

you should know this already considering you must define it for your u-boot port

 

if you're using a development board, then just look at the u-boot output or /proc/cpuinfo under Linux

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2008-12-01 14:44:20     Re: gptimer questions...

John Doe (UNITED STATES)

Message: 66109   

 

now i have a few questions:

 

does the timer automatically roll over to zero?

 

if it does is there some way from userspace that i can check this?

 

if it is 1/sclk then should i be getting more than ~1910 on the isr count every second?

 

I am trying to get to nano seconds using the timers under /dev. The file the I have been using to work from is the bfin_simple_timer.c. The resolution doesnt seem to finite enough for our project. is there anything that i can do to make the resolution in that file in nano seconds? Also, is there a way that i can clear or reset the timer?

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2008-12-01 17:00:51     Re: gptimer questions...

Mike Frysinger (UNITED STATES)

Message: 66111   

 

the HRM already describes the full behavior of the gptimer

 

the manual explains that the finesnt you can do with any peripheral is 1/SCLK

 

the driver source for bfin_simple_timer.c is pretty simple ... read the ioctl() function to see what it can do

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2008-12-02 01:41:26     Re: gptimer questions...

Wolfgang Muees (GERMANY)

Message: 66120   

 

It's a bit questionable to want to get the current time with a precision of 1 ns, if the code which retrieves this information has a much longer inaccuracy. You will never know how fast the code is executed due to cache and interupt behaviour.

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