Freescale Semiconductor MPC8260 - Manual (Page 583)

Serial Interface with Time-Slot Assigner
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 15-7
to 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.