User`s manual

DIGITAL-LOGIC AG MPC40/A/B/C, MPC41 Manual V1.4C

4.16 USB V2.0

USB Host controller functional description:

PIIX4 contains a USB Host Controller (HC). The Host Controller includes the root hub with two USB ports.

This permits connection of two USB peripheral devices directly to PIIX4 without an external hub. If more de-

vices are required, an external hub can be connected to either of the built-in ports. The USB’s PCI configura-

tion registers are located in function 2, PCI configuration space. The PIIX4 Host Controller completely sup-

ports the standard Universal Host Controller Interface (UHCI) and thus, takes advantage of the standard

software drivers written to be compatible with UHCI. Figure 9 shows a conceptual view of a USB system.

UHCI consists of two parts—Host Controller Driver (HCD) and Host Controller (HC). The Host Controller in-

terfaces to the USB system software in the host via the HCD. The HCD software manages the Host Control-

ler operation and is responsible for scheduling the traffic on USB by posting and maintaining transactions in

system memory. HCD is part of the system software and is typically provided by the operating system ven-

dor. HCD provides the software layer between the PIIX4’s Host Controller and the USBD software layer (also

located in the operating system). The UHCI’s HCD software interprets requests from the USBD and builds

Frame List, Transfer Descriptor, Queue Head, and data buffer data structures for the Host Controller. The

data structures are built in system memory and contain all necessary information to provide end-to-end

communication between client software in the host and devices on the USB. The PIIX4’s Host Controller

moves data between system memory and devices on the USB by processing these data structures and gen-

erating the transaction on USB. The Host Controller executes the schedule lists generated by HCD and re-

ports the status of transactions on the USB to HCD. Command execution includes generating serial bus to-

ken and data packets based on the command and initiating transmission on USB. For commands that re-

quire the Host Controller to receive data from the USB device, the Host Controller receives the data and then

transfers it to the system memory pointed to by the command. The UHCI’s HCD provides sufficient com-

mands and data to keep ahead of the Host Controller execution and analyzes the results as the commands

are completed.

For additional information on the functionality of PIIX4 USB Host Controller, refer to the Universal Host Con-

troller Interface (UHCI) Design Guide, Revision 1.1 available from Intel Literature Center with order number

297650- 002. Note that the UHCI Design Guide refers to USB ports 1 and 2. The PIIX4 USB ports are ports

0 and 1 respectively. Additions to the PIIX4 USB interface beyond UHCI, revision 1.1 include support for

over-current detection on USB ports 0 and 1. If an over-current condition is detected on a USB port, that port

will be disabled. Bits 10:11 in each Port Status and Control register are used to report over-current condi-

tions.

4.17 PCMCIA / PC-Card (only MPC40B)

Remark:

You can use only one 32Bit PCMCIA card in the MPC40B system.

That means, only one slot of the MPC40B supports 32Bit CardBUS. The second slot can be used with a

16Bit PCMCIA card