iSight FireWire interference

Yesterday we revived coverage of problems with the iSight interfering with the operation of other FireWire devices. The problem affects a broad variety of devices, including IEEE 1394 drives, scanners, the iPod and others.

Bruce Nofrey has a particularly bad case of iPod/iSight interference "Like other users, I have also had problems updating my iPod with the iSight camera connected. The iPod would continue to have the "do not disconnect" sign displayed - then the iPod would freeze ( clock not being updated) and finally my G4 tower would freeze. I have replaced one iPod and have talked to tech support when the second one did the same thing. We could not get the RESTORE function of the iPod Updater to recognize the iPod. Unplugging the iSight firewire cable from the computer will allow the iPod to be updated correctly.

(As noted below, iSight Updater 1.0.2 fixes a number of the iPod vs. iSight issues)

Meanwhile, MacFixIt reader Richard has two interesting theories on what might be causing the iSight interference issue:

"Different Mac models have different power availability on their firewire ports: current portables around 7 W peak, iMac LCD around 8 W shared over all ports and PowerMac cases around 15 W shared over all ports, thus limiting particular models to ability to support numerous bus powered devices and certainly restricting the length of any attached chain to significantly less than the theoretical 63 devices, where a bus powered device is attached (in my experience). So available bus power could be an issue for some FireWire device users."

"The iSight could well be using up all the bandwidth on the bus. Apple describe its as a 640 x 480, 30 FPS (frames per second), 24 bit color device conforming to the IIDC/DCAM specification. Checking this table suggests that up to 96% of the bandwidth on a 400 MBps (megabits per second) FireWire connection would be consumed, if running at full specification."

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On or off For some users, the problem occurs whether the iSight is on or off - as long as it is connected and receiving a signal, problems occur. Mike Cowan writes: "I have issues with my iSight causing the FireWire HD on my PowerMac G4 to drop from the bus. The iSight is connected but the aperture is closed and the iChat software is off."

Mac OS 9.2.2 worse? Marie Capitanio reports that the problem occurs under Mac OS 9.2.x, but not under Mac OS X 10.3.x: "I have both OSX 10.3.3 and OS 9.2.2 installed on separate volumes on my internal hard drive. When I boot up using OS 9.2.2 my external Western Digital hard drive (which is plugged into the second firewire port on my computer) disappears from the desktop, but not when I boot up with OSX 10.3.3. Once I unplugged iSight from the firewire port on the external hard drive the problem was corrected."

Workarounds For those who are having serious system problems when FireWire drives and the iSight are in use simultaneously, simply disconnecting FireWire drives during iSight usage is a hassling but complete workaround.

And for a number of users, updating to to version 1.0.2 of the iSight software alleviates major issues:

Tom Schuman "Prior to the iSight 1.0.2 updater my three daisy-chained external firewire hard drives (plugged into one of the firewire ports on a dual 1.42 GHz Power Mac G4) disappeared when an iSight camera was plugged into a firewire hub that is plugged into the other firewire port on the Power Mac G4. After some hassle I was able to mount the drives again with the iSight unplugged; I did not lose any data on the hard drives. The only way to avoid the drives from disappearing when the iSight was plugged in was to dismount each firewire drive and disconnect the drives from the firewire port on the Power Mac G4 prior to plugging in the iSight camera. After installing the iSight 1.0.2 updater the problem did not occur again. However the first time I plugged in the iSight camera after I upgraded to 10.3.3 one of the three hard drives (the oldest, about 4 years old) disappeared. I was able to remount it and no data was lost. Until a new fix is released, I'm back to my prior procedure of dismounting and unplugging the external firewire drives before I plug in the iSight camera."

As documented by Knowledge Base article #93705, the iSight 1.0.2 software is highly recommended "if you also use iPod mini, or more than one FireWire drive, including an iPod."

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