MPC8280 datasheet(940/1386 Pages) FREESCALE

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Fast Communications Controllers (FCCs)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

30-2

Freescale Semiconductor

Ethernet Controller,” and Chapter 31, “ATM Controller and AAL0, AAL1, and AAL5.” The FCCs are

independent from the physical interface, but FCC logic formats and manipulates data from the physical

interface. That is why the interfaces are described separately.

The FCC is described in terms of the protocol that it is chosen to run. When an FCC is programmed to a

certain protocol, it implements a certain level of functionality associated with that protocol. For most

protocols, this corresponds to portions of the link layer (layer 2 of the seven-layer OSI model). Many

functions of the FCC are common to all of the protocols. These functions are described in the FCC

description. Following that, the implementation details that differentiate protocols from one another are

discussed, beginning with the transparent protocol. Thus, the reader should read from this point to the

transparent protocol and then skip to the appropriate protocol. Since the FCCs use similar data structures

across all protocols, the reader's learning time decreases dramatically after understanding the first protocol.

Each FCC supports a number of protocols—Ethernet, HDLC/SDLC, ATM, and totally transparent

operation. Although the selected protocol usually applies to both the FCC transmitter and receiver, half of

one FCC can run transparent operation while the other runs HDLC/SDLC protocol. The internal clocks

(RCLK, TCLK) for each FCC can be programmed with either an external or internal source. The internal

clocks originate from one of the baud-rate generators or one of the external clock signals. The limitation

of the internal clocks frequency depends on the protocol being used, see Table 30-1. See Chapter 15,

“Serial Interface with Time-Slot Assigner.” However, the FCC’s ability to support a sustained bit stream

depends on the protocol as well as on other factors.

Each FCC can be connected to its own set of pins on the MPC8280. This configuration, the nonmultiplexed

serial interface, or NMSI, is described in Chapter 15, “Serial Interface with Time-Slot Assigner.” In this

configuration, each FCC can support the standard modem interface signals (RTS, CTS, and CD) through

the appropriate port pins and the interrupt controller. Additional handshake signals can be supported with

additional parallel I/O lines. The FCC block diagram is shown in Figure 30-1.

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