Reply by Paul Carpenter ●July 17, 20082008-07-17
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.

-- 
Paul Carpenter          | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/>    PC Services
<http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font
<http://www.gnuh8.org.uk/>  GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
<http://www.badweb.org.uk/> For those web sites you hate
Reply by lowcost ●July 17, 20082008-07-17
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
Reply by Adrian ●July 17, 20082008-07-17
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.
Reply by Anton Erasmus ●July 17, 20082008-07-17
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
Reply by Anton Erasmus ●July 17, 20082008-07-17
On Thu, 17 Jul 2008 09:23:42 +0200, "Peter Petersen" <pp@on-time.de>
wrote:


>Hello Anton,
>
>> 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
>
>Yes.
>
>> Or does the USB 2 link fall back to a 1.1 compatible mode ?
>
>No. It would do that with a full speed Hub, but not with a high speed
>(2.0) Hub.
>
>All the other posts in this thread are wrong. A USB 2.0 hub is an
>intelligent device which will repack the high speed communication coming
>from the host and resend it as full/low speed on its downstream ports.
>
>If you want to read about the details, see sections 11.1.1 and 11.14 of the
>USB 2.0 Spec (Hub Transaction Translator). USB 2.0 Hubs must be able to
>translate between high speed hosts and low/full speed donwstream devices.
>
>> So if I need to combine 6 full speed devices into one High speed
>> channel, I would need something with 6 1.1 host ports and one 2.0
>> device port.
>
>You need one high speed port on your host and one high speed Hub with 6
>downstream ports.


This is good news. 

Thanks for the info.

Regards
  Anton Erasmus
Reply by Anton Erasmus ●July 17, 20082008-07-17
On Wed, 16 Jul 2008 16:55:14 -0700 (PDT), Adrian
<adrianbica@yahoo.com> wrote:


>On Jul 16, 5:41 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:
>> Thanks, this what I needed to know. So if I need to combine 6 full
>> speed devices into one High speed channel, I would need something with
>> 6  1.1 host ports and one 2.0 device port.
>
>Basically, yes, but you need 2 host controllers to take care of those
>this devices, one would not be enough, because of the high bandwidth
>( 6 x 3Mbps). This should be two independent controllers, not a
>controller with 2 ports, those just have an internal (root) hub. And
>be sure the 2.0 device controller is a real 2.0, many controllers
>pretend they are 2.0 but limited to full speed.
>
>> available that does this kind of thing? I have six USB 1.1 devices
>> (FTDI chips in FIFO mode) each needing to send data at 3 Mbps to
>> a host PC. The PC has 6 USB ports, but I need to take these through a
>> sealed bulkhead, and the connectors I can get is to big to fit 6 of
>> them. So I either need to get smaller IP-67 sealed USB connectors, or
>> a way to combine the data into a single channel. I might be able to
>> fit 2 USB connectors in which case the Full Speed limit per channel
>> should be OK.
>>
>
>The PC also should have more than one internal USB host controllers,
>if it is just a hub, it won't do the job.


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
Reply by lowcost ●July 17, 20082008-07-17
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"

regards
Reply by Peter Petersen ●July 17, 20082008-07-17
Hello Anton,


> 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


Yes.


> Or does the USB 2 link fall back to a 1.1 compatible mode ?


No. It would do that with a full speed Hub, but not with a high speed
(2.0) Hub.

All the other posts in this thread are wrong. A USB 2.0 hub is an
intelligent device which will repack the high speed communication coming
from the host and resend it as full/low speed on its downstream ports.

If you want to read about the details, see sections 11.1.1 and 11.14 of the
USB 2.0 Spec (Hub Transaction Translator). USB 2.0 Hubs must be able to
translate between high speed hosts and low/full speed donwstream devices.


> So if I need to combine 6 full speed devices into one High speed
> channel, I would need something with 6 1.1 host ports and one 2.0
> device port.


You need one high speed port on your host and one high speed Hub with 6
downstream ports.

Peter
Reply by Adrian ●July 16, 20082008-07-16
On Jul 16, 5:41 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:

> Thanks, this what I needed to know. So if I need to combine 6 full
> speed devices into one High speed channel, I would need something with
> 6  1.1 host ports and one 2.0 device port.


Basically, yes, but you need 2 host controllers to take care of those
this devices, one would not be enough, because of the high bandwidth
( 6 x 3Mbps). This should be two independent controllers, not a
controller with 2 ports, those just have an internal (root) hub. And
be sure the 2.0 device controller is a real 2.0, many controllers
pretend they are 2.0 but limited to full speed.


> available that does this kind of thing? I have six USB 1.1 devices
> (FTDI chips in FIFO mode) each needing to send data at 3 Mbps to
> a host PC. The PC has 6 USB ports, but I need to take these through a
> sealed bulkhead, and the connectors I can get is to big to fit 6 of
> them. So I either need to get smaller IP-67 sealed USB connectors, or
> a way to combine the data into a single channel. I might be able to
> fit 2 USB connectors in which case the Full Speed limit per channel
> should be OK.
>


The PC also should have more than one internal USB host controllers,
if it is just a hub, it won't do the job.


> Regards
>   Anton Erasmus
Reply by Anton Erasmus ●July 16, 20082008-07-16
On Wed, 16 Jul 2008 21:18:30 +0100, "Peter Dickerson"
<firstname.lastname@REMOVE.tesco.net> wrote:


>"Adrian" <adrianbica@yahoo.com> wrote in message 
>news:c11ebd15-e7d7-4b6c-9a72-fac71de01b70@m3g2000hsc.googlegroups.com...
>> On Jul 16, 12:07 pm, Anton Erasmus <nob...@spam.prevent.net> wrote:
>>> Hi,
>>>
>>> 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 ? Or does the USB 2 link fall back to a 1.1 compatible mode ?
>>>
>>
>> Not sure what's your question, it is a bit confusing. The two
>> statements around the OR are equivalent.
>>
>> Briefly:
>> High speed = 480 Mbps (USB 2.0)
>> Full Speed = 12Mbps (USB 1.1)
>> Low Speed = 1.5Mbps (USB 1.1)
>> USB 2.0 is backward compatible, so is the hub. It should support a mix
>> of devices.
>>
>> So, yes, you get the 12Mbps full speed AND yes, the USB 2 link falls
>> back  to 1.1.
>
>And No, you don't get the 12 MB/s for each device. You still get 12 MB/s to 
>share.


Thanks, this what I needed to know. So if I need to combine 6 full
speed devices into one High speed channel, I would need something with
6  1.1 host ports and one 2.0 device port. Are there any chipsets
available that does this kind of thing? I have six USB 1.1 devices
(FTDI chips in FIFO mode) each needing to send data at 3 Mbps to
a host PC. The PC has 6 USB ports, but I need to take these through a
sealed bulkhead, and the connectors I can get is to big to fit 6 of
them. So I either need to get smaller IP-67 sealed USB connectors, or
a way to combine the data into a single channel. I might be able to
fit 2 USB connectors in which case the Full Speed limit per channel
should be OK.

Regards
  Anton Erasmus