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USB ID-pin missing -.no host in the system?

 
 
kturunen
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      01-17-2012, 12:29 PM
I'm relatively new with embedded systems and electronics so I might b
trying something above my skill level:
I have a Nokia N95 cellphone and an ARM mini-STM32 eval board wit
mini-USB-socket. The problem seems to be that I can use only 4 wires (ID i
floating on the board). What can I do to get my ARM-board and Noki
connected? Would a USB hub make either one of these devices a host?



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Tim Wescott
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      01-17-2012, 05:39 PM
On Tue, 17 Jan 2012 06:29:13 -0600, kturunen wrote:

> I'm relatively new with embedded systems and electronics so I might be
> trying something above my skill level: I have a Nokia N95 cellphone and
> an ARM mini-STM32 eval board with mini-USB-socket. The problem seems to
> be that I can use only 4 wires (ID is floating on the board). What can I
> do to get my ARM-board and Nokia connected? Would a USB hub make either
> one of these devices a host?


No. A host is a host from coast to coast. There are devices (Android
tablets come to mind, but I'm not sure how ubiquitous the scheme is) that
will autodetect and magically turn into hosts when necessary -- but for
the most part a device is either build with the functionality to be a
host, or the functionality to be a slave, and there ain't no in-between.

You probably have a better chance with your eval board, if the USB goes
straight to the processor. But it'd be a case of playing with the
software, and probably the hardware, to make it all go.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
 
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langwadt@fonz.dk
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      01-17-2012, 11:55 PM
On 17 Jan., 18:39, Tim Wescott <(E-Mail Removed)> wrote:
> On Tue, 17 Jan 2012 06:29:13 -0600, kturunen wrote:
> > I'm relatively new with embedded systems and electronics so I might be
> > trying something above my skill level: I have a Nokia N95 cellphone and
> > an ARM mini-STM32 eval board with mini-USB-socket. The problem seems to
> > be that I can use only 4 wires (ID is floating on the board). What can I
> > do to get my ARM-board and Nokia connected? Would a USB hub make either
> > one of these devices a host?

>
> No. *A host is a host from coast to coast. *There are devices (Android
> tablets come to mind, but I'm not sure how ubiquitous the scheme is) that
> will autodetect and magically turn into hosts when necessary -- but for
> the most part a device is either build with the functionality to be a
> host, or the functionality to be a slave, and there ain't no in-between.
>
> You probably have a better chance with your eval board, if the USB goes
> straight to the processor. *But it'd be a case of playing with the
> software, and probably the hardware, to make it all go.
>


some STM32s are usb-on-the-go and can be both host and device on the
fly,
there's protocols to agree on who gets to act as the host when you
plug
things together

but you could also just decide that you stm will be the host/device
and take it from there, it should backward compatible with

-Lasse
 
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kturunen
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      01-18-2012, 08:46 AM
This link below is to the board
http://www.kanebebe.com/download/min...2-V3.0_SCH.pdf

Can I solder the ID pin to something or am I just missing the hos
hardware?


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Robert Wessel
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      01-18-2012, 09:38 AM
On Wed, 18 Jan 2012 02:46:16 -0600, "kturunen"
<kturunen@n_o_s_p_a_m.gmail.com> wrote:

>This link below is to the board
>http://www.kanebebe.com/download/min...2-V3.0_SCH.pdf
>
>Can I solder the ID pin to something or am I just missing the host
>hardware?



ile the signaling is basically the same in both directions, a
peripheral and host have certain differences. For example, the host
supplies power, the peripheral does not. The host has pulldowns on
the signal lines, the peripheral has pullups to indicate function and
presence. Hosts that support high speed must also support full and
low speeds, a peripheral that supports high speed can not connect to a
low speed only host. The negotiation from full speed to high speed
also places certain roles on the two devices. The host runs the bus,
the peripheral (at the packet level is purely responsive). So there
are at least a few things to deal with. USB OTG, does provide help
here.

So with a bit of fiddling USB transceivers are capable of both roles.

But the real problem is the quite large software stack and functions
required on the host (often partially implemented in USB host chips).
A device designed as a peripheral simply has *none* of the stuff on
board needed to drive a USB bus. And while some might theoretically
be hackable, it is far from a small undertaking.

USB is *far* from being a simple connection like RS-232. While a
peripheral doesn't need too much intelligence (and easy to use USB
device/peripheral hardware is commonly available), the host has a very
large burden. If the device supports USB/OTG, it has a (slightly)
simplified host stack and can negotiate host mode when connected
point-to-point with a device.

And even if you have a proper USB host, it'll need an appropriate
driver to talk to the peripheral - for example, a number of tablets
can be USB hosts (usually USB/OTG), but only support mass storage
devices as peripherals (FWIW, many/most cameras can actually operate
in that mode). So you couldn't, for example, plug in your USB mouse,
and least not without getting HID-class support put on the host
system.
 
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kturunen
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      01-18-2012, 10:01 AM
...
>And even if you have a proper USB host, it'll need an appropriate
>driver to talk to the peripheral - for example, a number of tablets
>can be USB hosts (usually USB/OTG), but only support mass storage
>devices as peripherals (FWIW, many/most cameras can actually operate
>in that mode). So you couldn't, for example, plug in your USB mouse,
>and least not without getting HID-class support put on the host
>system.

OK, I get the picture - maybe I just plug the gsm modem and make it buz
with my ARM board. Yeah, thanks everybody.


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Anders.Montonen@kapsi.spam.stop.fi.invalid
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      01-18-2012, 10:48 AM
kturunen <kturunen@n_o_s_p_a_m.gmail.com> wrote:
> This link below is to the board
> http://www.kanebebe.com/download/min...2-V3.0_SCH.pdf
>
> Can I solder the ID pin to something or am I just missing the host
> hardware?


TheSTM32F103RB device used on that board only has a USB device interface.

-a
 
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