looking for an embedded linux hw.

[Erez D]

On Wed, Oct 5, 2011 at 10:18 AM, Baruch Siach <baruch at tkos.co.il> wrote:

> Hi Erez,
>
> On Wed, Oct 05, 2011 at 09:53:02AM +0200, Erez D wrote:
> > In the sheevaplug (actually i tested the dockstar).
> > i got the dockstar for 50USD in israel (used it as an eval board)
> > it has a 1GB ethernet, i read reports saying it is able to acheve actual
> > around 320Mbps rates as a router.
> > i was able to utilize it's serial port at 16Mbps. it is not the 30Mbps i
> > wanted, but will do for now.
>
> Wow. I didn't know that these rates are at all possible with a regular
> serial
> port. Did you do any special kernel modifications for this? Or is the
> BOTHER
> thing from include/asm-generic/termbits.h enough to make it just work?
>
> What limitation prevented you from doing 30Mbps, if I may ask?
>
> The serial baud rates are derived from a clock, which is divided by a
divider (and then usually divided again by 4).
you can set the baud rate to any tandard one (if supported by hardware).
however you can simply supply the divide_by value (if hardware supports
that, not all hw does, many usb-serial e.g. pl2303 based , does not support
that).
with setserial, you first set the baud to 38400, then enable speed_cust,
then set the divider to a value you want
with divider=1 i got around 13 or 16 Mbps.
as serial port usually uses a clock divided by 4 ( in addition to be divided
by the divider),
i guess the clk speed is around 13*4= about 50 Mhz.

so it seems the maximum speed should be around 13Mbps. full duplex of
course.

The problem with the dockstart (i think it is with any sheevaplug) is that
the hardware flow control pins are unavailable (without soldering + updating
the driver) so i work with xon/xoff.

erez.

> baruch
>
> --
>                                                     ~. .~   Tk Open Systems
> =}------------------------------------------------ooO--U--Ooo------------{=
>   - baruch at tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -
>
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