MPC8280 datasheet(585/1386 Pages) FREESCALE

585 / 1386 page

Serial Interface with Time-Slot Assigner

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

15-7

program the receive routing. SIx RAMs can be used to define the number of bits/bytes to be routed to the

MCC, FCC, SCC, or SMC and determine when external strobes are to be asserted and negated.

The size of the SIx RAM available for time-slot programming depends on the user’s configuration. The

user defines how many of the 256 entries are related to each TDM. The resolution of the division is by

fractions of 32. If on-the-fly changes are allowed, the SIx RAM entries are reduced according to the user’s

programming. The maximum frame length that can be supported in any configuration is 16,384 bits.

The maximum external serial clock that may be an input to the TSA is CPM CLK/3.

The SI supports two testing modes—echo and loopback.

•

The echo mode provides a return signal from the physical interface by retransmitting the signal it

has received. The physical interface echo mode differs from the individual FCC or SCC echo mode

in that it can operate on the entire TDM signal rather than just on a particular serial channel.

•

Loopback mode causes the physical interface to receive the same signal it is sending. The SI

loopback mode checks more than the individual serial loopback; it checks both the SI and the

internal channel routes.

NOTE

The flexibility described in the preceding section can be applied to each of

the four TDM channels and to all serial interfaces independently.

15.3

Enabling Connections to TSA

Each serial interface can be independently enabled to connect to one of the following: TSA, UTOPIA, MII,

or dedicated external pins. Note the following:

•

Each FCC can be connected to a dedicated MII or one of four TDMs. FCC1 can also be connected

to a 8-/16-bit UTOPIA level-2 interface; FCC2 can also be connected to an 8-bit UTOPIA level-2

interface.

•

Each SCC or SMC can be connected to one of four TDMs or to its own set of pins.

•

The MCC can be connected to one of the four TDMs with different numbers of channels.

The four TDMs are connected to four independent TDM interfaces. Figure 15-4 illustrates the connection

between the TSA and the serial interfaces. The connection is made by programming the CPM mux. See

Chapter 16, “CPM Multiplexing.” Once the connections are made, the exact routing decisions are made in

the SIx RAM.

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