Can an IEEE 1394 cable be plugged into a USB2 header?

Discussion in 'Motherboards' started by GTaudiophile, Nov 5, 2005.

  1. GTaudiophile

    GTaudiophile Lifer

    Joined:
    Oct 24, 2000
    Messages:
    29,768
    Likes Received:
    0
    I have this ECS 760GX-M motherboard in this Antec Minuet II case. The case has cables for the front panel: audio, IEEE 1394, and USB. The motherboard has the necessary audio headers and two USB 2.0 headers but no IEEE header. Of course the IEEE cable fits just fine onto the USB header. Can you still use the IEEE port at USB2.0 speeds?
     
  2. Tanclearas

    Tanclearas Senior member

    Joined:
    May 10, 2002
    Messages:
    345
    Likes Received:
    0
    No. You'll likely fry the board, but you'll at least fry the USB header.


    Edit: Posted prematurely. Damn my large hands! LOL!
     
  3. GTaudiophile

    GTaudiophile Lifer

    Joined:
    Oct 24, 2000
    Messages:
    29,768
    Likes Received:
    0
    Thanks. Just needed to be warned before I tried. Doesn't make sense that IEEE 1394 and USB cables are the same!
     
  4. evilharp

    evilharp Senior member

    Joined:
    Aug 19, 2005
    Messages:
    426
    Likes Received:
    0
    No.

    The standards are not compatible, and the pin-outs are very different. You could seriously mess up anything you plug into that port (the grounds and power pins are different).
     
  5. GTaudiophile

    GTaudiophile Lifer

    Joined:
    Oct 24, 2000
    Messages:
    29,768
    Likes Received:
    0
    Hmmm. They don't look different to me.
     
  6. GTaudiophile

    GTaudiophile Lifer

    Joined:
    Oct 24, 2000
    Messages:
    29,768
    Likes Received:
    0
    No additional comments on the picture I took? At the very least, teh fact these two cables are the same is confusing!
     
  7. mechBgon

    mechBgon Super Moderator<br>Elite Member

    Joined:
    Oct 31, 1999
    Messages:
    30,699
    Likes Received:
    0
    They look different to me... one says 1394 on it, the other says USB. :) You might as well add sugar to your car's gas tank, if you're going to plug the Firewire cable into the USB header.

    The wire pinout on the USB cable is undoubtedly the typical

    +5V . Data- . Data+ . Ground . Ground
    +5V . Data- . Data+ . Ground

    And the firewire cable would be

    DataA- . Ground . DataB- . +12V . Ground
    DataA+ . Ground . DataB+ . +12V


    So if you match 'em up, then if you plug a Firewire device into a Firewire port that's attached to a USB header, your iPod (or whatever) will get hot 5-volt power on its twisted-pair-A data lines (bad!), and grounds on one of its two twisted-pair data cables and its 12V lines. So I believe you'd probably ruin the iPod point-blank. Possibly the motherboard too.
     
  8. evilharp

    evilharp Senior member

    Joined:
    Aug 19, 2005
    Messages:
    426
    Likes Received:
    0

    As mechbgon indicated, they are similar but they are very different.

    Both use 10 pins, but the pins are assigned to different functions. Thankfully, both USB and 1394 have been standardized, so the pinouts are as follows:

    USB2

    1 - power
    2 - power
    3 - USB Dx-
    4 - USB Dy-
    5 - USB Dx+
    6 - USB Dy+
    7 - GND
    8 - GND
    9 - No Pin (cable usually plugged to prevent use on Firewire)
    10 - NC

    1394 (Firewire)

    1 - TPA2+
    2 - TPA2-
    3 - GND
    4 - GND
    5 - TPB2+
    6 - TPB2-
    7 - No Pin (cable usually plugged to prevent use on USB)
    8 - Power
    9 - Power
    10 - GND

    The odd cable manufacturer doesn't use "blocked" connectors to save on money, which causes headaches for the end user. As you can see, the signal, power and ground pins are all different, which is to be expected as the standards are very different.
     
Loading...