Motorola MPC8260 - Manual (Page 491)

MOTOROLA Chapter 15. CPM Multiplexing 15-1
Chapter 15
CPM Multiplexing
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150
The CPM multiplexing logic (CMX) connects the physical layerÑUTOPIA, MII, modem
lines, TDM lines and proprietary serial lines to the FCCs, SCCs and SMCs. The CMX
features the following two modes:
¥ In NMSI mode, the CMX allows all serial devices to be connected to their own set
of individual pins. Each serial device that connects to the external world in this way
is said to connect to a nonmultiplexed serial interface (NMSI). In the NMSI
conÞguration, the CMX provides a ßexible clocking assignment for each FCC, SCC
and SMC from a bank of external clock pins and/or internal BRGs.
¥ In TDM mode, the CMX performs the connection of the serial devices to the SIs for
using the time-slot assigner (TSA). This allows any combination of MCCs, FCCs,
SCCs, and SMCs to multiplex data on any of the eight TDM channels. The CMX
connects the serial device only to the TSA in the SIx. The actual multiplexing of the
TDM is made by programming the SIx RAM. In TDM mode, all other pins used in
NMSI mode are available for other purposes. See Chapter 14, ÒSerial Interface with
Time-Slot Assigner.Ó
The CMX also allows the user to route the multiple-PHY address to FCC1 or to FCC2 in
various combinations, allowing the use of both FCCs in multiple-PHY mode.
NOTE
The CMX serves both SI1 and SI2. When the user programs the
CMX to connect a serial device to the SI, the CMX connects
that serial device to both SIs. Programming both SIs to use one
serial device in the same time slot causes erratic behavior.
Figure 15-1 shows a block diagram of the CMX.