Hi,
Anouk Ahamitet <> [20080619 14:17:59 -0000]:
>
> --- In "charliem_1216" <>
> wrote:
>
> >... Better to fix your A/D code so it is insensitive to system load.
>
> We're working on it, but since ts-linux doesn't have very accurate
> timers (minimum usleep() appears to be almost 10 MILLISECONDS and the
> min nanosleep() is about 3.5 MILLISECONDS) we're stuck doing a busy wait
> on the built-in microsecond timer on the TS-7800 in order to get
> accurate (and fast) enough timing on our A/D operations (note: we're
> using a 3rd party A/D, not one of Technologic's because the TS A/Ds
> don't support the input voltage ranges we require and/or don't have
> enough resolution).
>
> We wish that Technologic had altered their custom kernel to use their
> high resolution (microsecond) timer on the TS-7800 or at least offered a
> customer HRT device that used it to offer precision delays. As it is,
> we either need to add learning to write linux device drivers to our
> schedule, or stick with the busy waits while reading the current
> microsecond from their timer that we are doing now. If the timer
> could've been used as a precision count-down timer that generated a
> signal (or interrupt or whatever) we use it that way to keep our app
> from spending 99.9% of its time from spinning while reading the next
> microsecond. Maybe the 7800 Mark II will have that... (I can dream,
> right?)
>
<shameless_plug>
with my vanilla (orion5x) patch, having just solved the RTC, random entropy
gatherer and NAND HW ECC I was looking at the remaining low hanging fruit.
The timer is one of them.
</shameless_plug>
The disadvantage, no DMA NAND access and of course no SD card access with my
kernel...that might be the killer for you? I was going to look at the other
UART's and the cute LED's and the LCD however if someone actually is keen on
the timer support...
The driver's would not be portable to the regular TS kernel though.
Cheers
Alex
> > Of course, stopping un-needed process like you are doing is always
> > good in any case.
>
> Agreed. [:)]
>
> > What kernel version are you using?
>
> From the login prompt, /etc/issue, and /proc/version (respectively):
>
> Debian GNU/Linux 3.1 ts7800
>
> Debian GNU/Linux 3.1 \n \l
>
> Linux version 2.6.21-ts (gcc version 3.4.4
> (release) (CodeSourcery ARM 2005q3-2)) #4 PREEMPT Tue Jun 10 17:13:00
> MST 2008
>
>
>
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