MPC8280 datasheet(825/1386 Pages) FREESCALE

825 / 1386 page

Universal Serial Bus Controller

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

27-9

When USMOD[TEST] is programmed, both the host state machine and function state machine are active.

End points 2-4 receive/transmit data according to tokens received from host. The programming model and

functional description are described in Section 27.5.7, “USB Function Programming Model.”

Figure 27-5. USB Controller Operating Modes

27.5.1.1

Packet-Level Interface

If USEP1[RTE] is 0, the USB host controller uses a packet-level interface to communicate with the user.

Each transmit packet is prepared in a buffer and referenced by a TxBD as described in Section 27.6.3,

“USB Transmit Buffer Descriptor (Tx BD) for Host.” Each receive packet is stored in a buffer referenced

by a RxBD as described in Section 27.6.1, “USB Receive Buffer Descriptor (Rx BD) for Host and

Function.” A SETUP or OUT transaction requires at least two TxBDs, one for the token and one or more

for the data packet. An IN transaction requires one TxBD for the token and one or more RxBDs for the

data packet. Tokens are not checked for validity and are transmitted as is. The user is responsible for token

validity as well as CRC5 generation.

27.5.1.2

Transaction-Level Interface

NOTE

The transaction-level interface described in this section is available only on

.13

µm (HiP7) Revision A.0 and future devices.

Reset

IDLE

Setup

Transmit

Receive

SETUP

token

OUT

token

PREAMBLE

Low Speed

Full

Speed

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