[Arm-netbook] Doubt about USB in EOMA-68.

[Luke Kenneth Casson Leighton]

On Fri, Jun 13, 2014 at 8:40 AM, Miguel Garcia <gacuest at gmail.com> wrote:
> Hi all,
> I've been looking at this:
> http://elinux.org/Embedded_Open_Modular_Architecture/EOMA-68#Table_of_EOMA-68_pinouts
>
> Are all EOMA-68 obliged to have 2 USB 2.0 (the first on pin 30 and 64,

*correction*  ....and optionally 20, 21, 54 and 55:

* 20 ---- not used ---- / USB3 StdA_SSRX-* 54 ---- not used ---- /
USB3 StdA_SSRX+
* 21 ---- not used ---- / USB3 StdA_SSTX-* 55 ---- not used ---- /
USB3 StdA_SSTX+
* 30 1st USB2 (Data+)* 64 1st USB2 (Data−)

....

> the second on pin 34 and 68)?

 ... which is the 2nd USB port and will remain absolutely at the
maximum of up to USB 2.0 because there are only 2 pins available:

* 34 2nd USB2 (Data+)* 68 2nd USB2 (Data−)


 answer: you misunderstand the spec.

 there must be 2 USB ports *of any type*, absolute minimum is USB 1.0,
with upward-compatibility *required* up to the absolute maximum
possible capability of the card's hardware.

 so the TI OMAP35xx series *MAY NOT* be used (directly) because they
ONLY support USB 2.0 480mbit/sec.


> If in the future there is a EOMA-68 compatible with USB 3.0, would
> this USB 3.0 be associated with the first USB 2.0 or the second USB
> 2.0?

 first.  always and only the first.  that should be clear in the spec.
it is at least implicitly clear because the first port pins (6of) are
only available for USB3, whereas the 2nd is only 2 pins (USB2)

> We want to use the USB 3.0 to create a USB 3.0 port (with the current
> EOMA-68 only be compatible with USB 2.0, but we want to be compatible
> in the future with USB 3.0) and use the other USB 2.0 to connect
> internally the WIFI, the BT, the USB IC audio .... And we do not want
> that, in the future, some new EOMA-68 be incompatible with this
> because we have chosen the wrong USB.

 ... which is exactly why it won't change.  basically once the first
hardware is out, the spec is "nailed" for ... well... forever.  which
is why it's good to have caught the things we have in the past couple
of months.

l.