pcmcia cardbus not powering firewire.Help

Do you have a question? Post it now! No Registration Necessary.  Now with pictures!

Threaded View

I have a Skymaster Cardbus firewire 400 that's not providing power to my
firewire 410 audio device.
Can anyone offer any insight as to why its not powering the firewire device.

Ive tested on two laptops.
It works with external power supply on laptops and works on the desktop
pci card without dc adapter.

Device is M-Audio 410.

Thanks Heaps,,,,

Re: pcmcia cardbus not powering firewire.Help

hj wrote:
Quoted text here. Click to load it

There are two kinds of Firewire400 connectors. One kind has four pins and
one kind has six pins. The six pin one carries bus power. The four pin
does not. (If a four pin connector is used somewhere in the cabling
scheme, then the target device needs its own power adapter and a
separate input power connector.)


Examine the cabling scheme you are using. If the Skymaster Cardbus
has a four pin connector on it, then that is saying "we don't provide
bus power". If the Skymaster Cardbus has a six pin connector on it,
then you really don't know for sure whether there is sufficient or
any power on the extra pins or not.

The Cardbus pinout (part plugging into laptop) has two VCC pins,
a VPP1 pin and a VPP2 pin. I don't have a copy of the Cardbus spec,
and based on a FAQ entry on the pcmcia.org  site, the VPP1 and VPP2
are programmable. They can have 12V placed on them by the laptop
(power might even come right from the battery pack). If that was
connected to Firewire bus power, it might be a match for the 1.5 amps
max current flow.

Firewire allows a wide range of bus power voltages to be used. Apple
may have used the higher voltage level (allowing more total power
to flow) on some of their stuff. But for the most part, things
like desktop PCs use 12V on the bus power pins. So you'd have
about 12V @ 1.5A to play with perhaps.

What a laptop chooses to do, in terms of the voltage and current
available on VPP1 and VPP2, could be different for all I know.
Maybe the limitation is related to whatever scheme the laptop
uses, to provide power to VPP1 and VPP2. It might even be a failure
to switch to 12V mode when asked by the plugin Cardbus card.

According to the M-audio user manual, the thing comes with a
12V @ 1A wall adapter, to power the 410 if using a four wire
Firewire cable. That should give some idea of the max
power it might consume (it doesn't have to use the whole 1 amp).
The 410 also appears to have some kind of low power mode, and
you might use that fact to determine whether any power is
available from the laptop at all.


It could be, that the laptop is just providing 5V on VPP1
and VPP2, which might not be enough for bus power on Firewire.

I don't recommend probing for power with a multimeter, unless
you've taken strict precautions to prevent shorting while making
measurements. Even a momentary contact, between the VPP (12V or
higher) pin, and one of the four data pins on a Firewire connector,
could be instantly fatal to the devices on the cable at the time.
Instead, use the evidence you're seeing from the 410 itself, to
tell you whether some, a little, or no power is coming from the
laptop. (I don't even have the necessary insulated wire contact
needed here to make the measurement, and I have three or four
multimeters :-) )


Re: pcmcia cardbus not powering firewire.Help

Paul wrote:
Quoted text here. Click to load it
I'm using a 6 pin.
Quoted text here. Click to load it
Thanks for the link
Quoted text here. Click to load it
Could be laptop?

Quoted text here. Click to load it
No blue light (low power mode)

Quoted text here. Click to load it
RTFM, thanks.
That could explain it.

Quoted text here. Click to load it

No need for probing, I think your right that its only supplying 5 volt ,
waiting for answer from supplier.
If so it would be good to enable 12v if possible.

Funny how i couldn't find anyone mentioning this problem on any forums

Thanks so much Paul for all this useful information.

Re: pcmcia cardbus not powering firewire.Help

According tp the supplier the Firewire Cardbus 400 doesnt supply power.
Can anybody confirm or suggest a pcmcia firewire card that does?
hj wrote:
Quoted text here. Click to load it

Re: pcmcia cardbus not powering firewire.Help

hj wrote:
Quoted text here. Click to load it


One of the reviews says:

   "You may find, like I did, that the card is incapable of powering
    anything without a 12V DC wall wart (Adaptec's won't work, but I found
    a cheapie at K-Mart that is fine...center pin positive, outer shield


So that is an example of a product that doesn't support bus power,
unless an external adapter is connected.

This one has a power connector for fitting an adapter, on the front.



    "Normally, DV devices will function without a power adapter. If a power
     adapter is necessary, please use the Upgrade Kit Order Form in the package,
     or contact sales@siig.com and order the power adapter. The power adapter
     is part number NN-ADAP11, model number NN2623.

     Alternatively, you can use any power adapter that meets the following

     Output: +12V DC at 1A
     Connector: Positive inside, negative outside"

It is on the front of this IOGear one.


This one suspiciously bundles a 6 pin to 4 pin cable, and there are no
power adapter holes at all to be seen on the card. The manual makes
no mention of power at all.


OK, finally! This one lists 500mA per port. That is not enough power to
run a bus powered 3.5" hard drive. Check your Firewire device specs to
see if 500mA is enough.

http://trendnet.com/download_manager/?iFile=3223&File=D :\FTP\TFW-H2PC\DataSheet\EN_Spec_TFW-H2PC.pdf&Name=EN_Spec_TFW-H2PC.pdf&Size=210679
TRENDnet TFW-H2PC IEEE 1394 PCMCIA Card 2 x IEEE 1394 - Retail  $23

 From the Unibrain site:

    2) Why can't I charge my iPod from FireCard 400 even though it has
       a 6 pin port?

       The PCMCIA bus specification does not provide enough power to allow
       the PCMCIA cards to power external devices. Therefore, the PCMCIA
       Firewire cards do not provide enough power to the Firewire bus.

Which of course, begs the question, why put a six pin connector on the
stupid things, if they provide no bus power at all ? At least the
Trendnet people were clever enough to give a number for the power
level they think they can support, which is better than nothing.
For the ones that use a separate adapter, whatever the adapter limit
is, could limit the current available at a connector.

One deal is, the PCMCIA pins can only carry so much current. So if
any of these cards, really do use VPP1/VPP2 pins to get Firewire bus
power, they would be limited by the safe current carrying capacity
of those two pins. If the card is not properly fused, in fact you
could draw more power than is safe, and the pins could get burned in
the PCMCIA socket. Presumably, they use something like a Polyfuse
(a self-resetting fuse) to limit the current, as one of those is
cheap and does the job pretty well. If the bus power disappears suddenly,
that could be a Polyfuse opening up. When it cools off, it closes again.
It needs time to return to its original crystalline shape, and if used
immediately after it closes, may open a little easier the second
time. After a few hours, it should be more or less like it was before.


Site Timeline