MPC8280 datasheet(821/1386 Pages) FREESCALE

821 / 1386 page

Universal Serial Bus Controller

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

27-5

Figure 27-2. USB Function Block Diagram

27.4.1

USB Function Controller Transmit/Receive

After reset condition, the USB function is addressable at the default address (0x00). During the

enumeration process the USB function is assigned by the host with a unique address. The USB slave

address register (refer to Section 27.5.7.2, “USB Slave Address Register (USADR)”) should be

programmed with the assigned address. The USB function controller supports four independent endpoints.

Each endpoint can be configured to support either control, interrupt, bulk, or isochronous transfers modes.

This is done by programming the endpoint registers (refer to Section 27.5.7.3, “USB Endpoint Registers

(USEP1–USEP4)”).

NOTE

It is mandatory that endpoint 0 be configured as a control transfer type. This

endpoint is used by the USB system software as a control pipe. Additional

control pipes may be provided by other endpoints.

Once enabled, the USB function controller looks for valid token packets. Figure 27-3 and Table 27-2

describe the behavior of the USB controller for each token. Tokens that are not valid (that is, PID check

fails or CRC check fails or packet length is not 3 bytes) are ignored by the USB function controller.

Mode register

Peripheral bus

U-bus

Command register

Port control

Transmitter

Receiver

USB function

DPLL/

Bus Interface

Rx FIFO

Tx data FIFO

mode register

Endpoint

registers

Address

Port configuration

External transceiver

state machine

16-byte

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