On Fri, Jul 09, 1999 at 02:37:05PM -0700, Alexander Mikhailov wrote:
>
> > (Actually, now that I think about it, the 3com 3c905b has such a
> > counter, and is ~USD 60. What a bargain. What a hack. But hey,
> > if it works...)
>
> What a good idea ;) is it then possible for the NIC to work as a NIC
> too? Could you provide more details?
>
I'm pretty sure its possible to use it as a NIC at the same time.
However, that means that you will have to make your network interrupt
real-time, and write a real-time interrupt routine that checks for a
timer interrupt. If it's not a timer interrupt, then trigger
a Linux interrupt. Under heavy network load, this means you'll get
*lots* of RT interrupts, which is exactly the opposite of the purpose
of RTLinux. *I* wouldn't rely on it...
Upon looking at the docs, the 3c905b has a 16 bit countdown timer
that does not have a reload register. It can count at a rate of 3.2 us
or 320 ns. It also has a free-running, non-programmable 16 bit
counter, and another similar 24 bit counter that counts at 800 ns.
The 24 bit counter can be used for scheduling packet transmit. I
suppose it could be hacked to send a packet of known size, and
interrupt when done... *shudder*.
So this board is only slightly better than the ISA 8254, because its
on the PCI bus. However, I wouldn't be surprised if there are other
cheap boards that have better timers.
dave...
--- [rtl] ---
To unsubscribe:
echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR
echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED]
----
For more information on Real-Time Linux see:
http://www.rtlinux.org/~rtlinux/
