Wish for 2nd generation Neo: USB 2.0

[michael at michaelshiloh.com]

On Sun, 21 Jan 2007, Koen Kooi wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Harald Welte schreef:
>> On Thu, Jan 18, 2007 at 10:23:24AM +0100, Sven Neuhaus wrote:
>>> Since everyone is drooling about the next iteration of the Neo which is
>>> exptected to include WiFi, I figured I'd add a request for USB 2.0. This
>>> allows us to use a USB VGA adapter
>>> (http://www.tomshardware.com/2005/06/08/add_a_monitor_using_usb/ - Linux
>>> driver available!). A VGA port enables the Neo2 to replace a laptop for
>>> doing presentations (in some cases) and you could even watch movies stored
>>> on its microSD card (or streamed by a BluOnyx) on a battery powered HMD! :-)
>>
>> Thanks, this has actually already been on our wishlist for a future
>> generation of our phones.
>>
>> The main problem (with more powerful SoC) is not to provide a USB2.0
>> host port in the device.  The main problem is power.  You need a pretty
>> powerful DC/DC step-up converter to provide the 5V power supply to the
>> USB bus.  And you have to provide at least up to 100mA - but to support
>> all devices, 500mA.
>
> Newer SoCs like the omap2 series feature a charge pump for +5V to get at least detection
> working. That would simplify things a lot since the hub doesn't have to provide power
> 'upstream' anymore.
>
> Another thing to keep in mind: with 500mA you'll drain your 1200mAh batter in little over
> 2 hours with USB *alone*.

Of course in the case of VGA, we presume you have AC power nearby and can
provide external power to the USB device via something like a powered USB hub.
No, it's not super elegant, but it works. Trying to find the right balance
between low power/long battery life vs. fancy power-hungry USB devices
requires this sometimes.

Michael