Motorola PowerQUICC II MPC8280 Series Reference Manual page 992

Freescale Semiconductor, Inc.
Overview
30.1 Overview
MPC8280 FCCs can be configured independently to implement different protocols.
Together, they can be used to implement bridging functions, routers, and gateways, and to
interface with a wide variety of standard WANs, LANs, and proprietary networks. FCCs
have many physical interface options such as interfacing to TDM buses, ISDN buses,
standard modem interfaces, fast Ethernet interface (MII), and ATM interfaces (UTOPIA);
see Chapter 15, "Serial Interface with Time-Slot Assigner," Chapter 36, "Fast 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.
30-2 MPC8280 PowerQUICC II Family Reference Manual MOTOROLA
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