On Fri, 2 Dec 2011, sunnyliu2005 wrote:
> How resolution about to call usleep? Is it in micro-second?
> Does the GPIO can create digital pulse with usleep?
> Are there have any limitation?
This is an FAQ.
The problem is generic for linux.
The basic interval timing provided by linux has traditionally been based on
the timing interval used to count jiffies, typically 100Hz. This clock tick
is used for scheduling etc, and effectively restricts the minimum usleep
etc wait to 10millisec. In a loop using 2 such waits, one to send the
signal low and one to send it high, you can generate a 50Hz signal.
For higher frequencies you usually need to resort to using any spare timer
that may be available in the processor core, (I believe there is one in the
ts7250 board) and writing some sort of interrupt driven kernel driver.
>
>
> My TS-7250 run origin release version Linux version :
>
> Linux version 2.4.26-ts11 (gcc version 3.3.4) #3 Tue Jun 6
> 14:13:14 MST 2006
>
> CPU: Arm920Tid(wb) revision 0
>
> Machine: ep9301
>
> Build AP toolchain : crosstool-cygwin-gcc-3.3.4-glibc-2.3.2.tar.bz2
>
> Please help me! That is my second post message. The first one is disappear
> here!
>
> Best regards,
>
> Sunny Liu
>
>
------------------------------------
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/ts-7000/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/ts-7000/join
(Yahoo! ID required)
<*> To change settings via email:
<*> To unsubscribe from this group, send an email to:
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
|