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FireWire 400 Port

The 12-inch PowerBook G4 has one external FireWire 400 IEEE 1394a port. The FireWire 400 port

• supports serial I/O at 100, 200, and 400 Mbps (megabits per second)

• provides up to 7 watts of peak power when the computer system is on or the power adapter is connected.

• supports booting the system from a mass storage device

• supports target disk mode (TDM)

The FireWire 400 hardware and software provided with the 12-inch PowerBook G4 are capable of all asynchronous and isochronous transfers defined by IEEE standard 1394a.

In this section:

FireWire 400 Connector
FireWire Device Programming

FireWire 400 Connector

The FireWire 400 connector has six contacts, as shown in “Figure 3-2.” The connector pin assignments are shown in Table 3-2.

The FireWire power pin provides a maximum voltage of 12.6 V (no load) and up to 7 W peak power. Power is supplied to the FireWire port when

• the computer is awake or asleep with the power adapter connected

• the computer is awake on battery power with the power adapter not connected

Power is not supplied to the FireWire port when the computer is shutdown; or is asleep with the power adapter not connected.

The signal pairs are crossed in the cable itself so that pins 5 and 6 at one end of the cable connect with pins 3 and 4 at the other end. When transmitting, pins 3 and 4 carry data and pins 5 and 6 carry clock; when receiving, the reverse is true.

FireWire Device Programming

Mac OS X includes general support for the FireWire bus and specific support for various kinds of FireWire devices and protocols. Developers can use the built-in support or provide additional applications and drivers for use with their products.

The general FireWire services will configure the FireWire bus, scan the bus for new devices, and allow multiple drivers and devices to share a single FireWire interface cooperatively. The general services also publish information about the bus and the devices in the IO Registry, so that IO Kit can match protocols and drivers to each connected FireWire device.

The specific device and protocol support in Mac OS X as provided with the 12-inch PowerBook G4 includes the following:

• General services for Serial Bus Protocol 2 (SBP-2) and support for most mass storage devices using SBP-2, such as hard disk drives, optical drives, flash card readers, Target Disk Mode (see “Target Disk Mode,” and the iPod. Mac OS X can boot from most of these devices.

• General services for the Audio Video Control (AV/C) protocol and support for most digital video (DV) cameras and decks using this protocol, including video capture through standard QuickTime APIs.

• A QuickTime device driver for IIDC/DCAM type cameras such as the iSight.

• A network device driver supporting IP (Internet Protocol) over FireWire according to IEEE RFC 2734.

• Additional services for user-space and kernel access to all FireWire resources.

For information on writing FireWire drivers or applications, download the latest FireWire SDK from http://developer.apple.com/sdk/

For additional references, refer to “FireWire 400 Interface.”

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