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USB 2.0 Ports

The 12-inch PowerBook G4 has two external Universal Serial Bus (USB) 2.0 ports that can be used to connect additional I/O devices such as a USB mouse, printers, scanners, and storage devices.

For more information about USB on Macintosh computers, please refer to sources listed in “USB Interface.”

In this section:

USB Connectors
USB Technology
USB Device Programming

USB Connectors

The USB port uses a USB Type A connector, which has four pins. Two of the pins are used for power and two for data. Figure 3-1 is an illustration of a Type A USB port. Table 3-1 shows the pin assignments.

The 12-inch PowerBook G4 provides power for the USB ports at 5 V and up to 500 mA each.

The external USB 2.0 ports support low-speed (1.5 Mbps), full-speed (12 Mbps), and high-speed (480 Mbps) data transfers. High-speed operation requires the use of shielded cables.

The Macintosh USB system software that comes with the 12-inch PowerBook G4 supports all four data transfer types defined in the USB specification.

USB Technology

The USB ports include power saving modes, support of USB mass-storage devices, and an EHCI controller.

Wake on Connect and Resume

The Intrepid IC contains special circuitry that allows the computer to wake from sleep mode on connect, disconnect, and resume events. Compatible USB devices should support the USB-suspend mode defined in the USB specification.

USB Class Drivers

Class drivers are software components that are able to communicate with many USB devices of a particular kind. If the appropriate class driver is present, any number of compliant devices can be plugged in and start working immediately without the need to install additional software. For information about USB support on the Macintosh, see the references in “USB Interface.”

USB Controller

The 12-inch PowerBook G4 uses an Enhanced Host Controller Interface (EHCI) controller for USB communication. Some early USB devices (most notably keyboards) can’t interoperate with an OHCI controller. Those devices are not supported by the Macintosh USB system software.

USB Device Programming

Mac OS X includes support for a variety of USB Class Compliant devices and provides access to vendor specific devices. Developers can use the built-in support or provide additional applications and drivers.

In Mac OS X, The USB Family (IOUSBFamily) handles device plug and unplug andsupplies IOKit with a USB-specific matching method. The general services publish information about the bus and the devices in the IO Registry, so that IO Kit can match drivers to each connected USB device.

In the 12-inch PowerBook G4, Mac OS X provides the following USB class compliant drivers:

• Audio

• Bluetooth

• CDC (Communication Data Class)

  • modem (abstract control model only)

• HID (Human Interface Device)

  • boot protocol

  • report protocol

• HUB

• Mass storage

• MIDI

• Printer

• Still image/PTP (digital still cameras)

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

For information about USB support on the Macintosh, see the references in “USB Interface.”

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