Multiple USB 1.1 devices in USB 2 Hub speed ?

On Thu, 17 Jul 2008 14:59:05 +0200, lowcost <die.spam@invalid.com>
wrote:

>Anton Erasmus ha scritto:
>> If I have a number of USB 1.1 devices plugged into a USB 2 Hub, can I
>> get the full 12MB/s  of each USB 1.1 device via the USB 2 link to a
>> host ?
>
>yes, if the hub is " _multiple_ Transaction Translator"
>
> > Or does the USB 2 link fall back to a 1.1 compatible mode ?
>
>yes, if the hub is " _single_ Transaction Translator"
>

I have never seen this on the spec sheet of a USB Hub. Not that one
get much in the way of documentation with these type of products.
Are there any reputable manufacturers of USB hubs which gives these
sort of specs, and which wil operate from -20 deg C to 85 deg C ?

Regards
  Anton Erasmus

On Jul 17, 3:54 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:
>
> Thanks, I did not think of this. Is an internal USB hub the norm for
> PCs, or is it normally more than one host controller ?
>
> Regards
>   Anton Erasmus

Usually, computers have more than one USB controllers. You can see
this in Device Manager, under USB Controllers section. The host
controllers are listed there, as well as the root hubs, normally one
per controller. Have to find the link between connectors and
controllers.
However, the other answers are correct, a 2.0 Hub will convert the
speed from Full to High. (Sorry for misinformation, what I was saying
is true for Full speed hubs, they use the actual speed of the device.
I didn't play too much with 2.0 hubs. My bad.) In this case looks like
you can use a hub and do not worry about speed because it is
translated to High speed. Not sure if you can find a 2.0 hub with 6
ports, and I'm not sure if the hub has a host controller for each port
or uses one for all (which will give you the same bandwidth problem).
But, if you use 2 hubs with 3 devices on each, that would be ok.

Anton Erasmus ha scritto:
> I have never seen this on the spec sheet of a USB Hub. Not that one
> get much in the way of documentation with these type of products.
> Are there any reputable manufacturers of USB hubs which gives these
> sort of specs, and which wil operate from -20 deg C to 85 deg C ?

google (all words): usb hub multi TT

regards

In article <109v74hdgrm1k8vfp1ngmpagp5c4tcanhu@4ax.com>, 
nobody@spam.prevent.net says...
> On Thu, 17 Jul 2008 14:59:05 +0200, lowcost <die.spam@invalid.com>
> wrote:
> 
> >Anton Erasmus ha scritto:
> >> If I have a number of USB 1.1 devices plugged into a USB 2 Hub, can I
> >> get the full 12MB/s  of each USB 1.1 device via the USB 2 link to a
> >> host ?
> >
> >yes, if the hub is " _multiple_ Transaction Translator"
> >
> > > Or does the USB 2 link fall back to a 1.1 compatible mode ?
> >
> >yes, if the hub is " _single_ Transaction Translator"
> >
> 
> I have never seen this on the spec sheet of a USB Hub. Not that one
> get much in the way of documentation with these type of products.
> Are there any reputable manufacturers of USB hubs which gives these
> sort of specs, and which wil operate from -20 deg C to 85 deg C ?
 
Not that difficult to do your own!

Look at NXP ISP1520 4 port Multiple transaction USB2.0 hub in ONE device.
They also do a SEVEN port device. This would suit person with 6 x FTDI 
devices. You would have to check temp specs, myu spec says -40 to +70, 
but find out if they do an industrial/automotive grade part.

ISP1520 can be used with no EEPROM or anything much else. Made a 3 port 
one from it for one design where it was on board with rest of circuitry.
One of the ports was a permanently connected FTDI device.

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