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

Discussion in 'Embedded' started by kturunen, Jan 17, 2012.

  1. kturunen

    kturunen Guest

    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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    kturunen, Jan 17, 2012
    #1
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  2. kturunen

    Tim Wescott Guest

    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
     
    Tim Wescott, Jan 17, 2012
    #2
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  3. kturunen

    Guest

    On 17 Jan., 18:39, Tim Wescott <> 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
     
    , Jan 17, 2012
    #3
  4. kturunen

    kturunen Guest

    kturunen, Jan 18, 2012
    #4
  5. 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/mini-stm32/MINI_STM32-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.
     
    Robert Wessel, Jan 18, 2012
    #5
  6. kturunen

    kturunen Guest

    ...
    >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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    kturunen, Jan 18, 2012
    #6
  7. kturunen

    Guest

    , Jan 18, 2012
    #7
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