Freescale Semiconductor PowerQUICC MPC885 Reference Manual page 610

Serial Interface
The NMSI, discussed in
• Each SCC and SMC can be programmed independently to work with its own set of
non-multiplexed signals.
• Each SCC can have its own set of modem control signals.
• Each SMC can have its own set of four signals.
• Each SCC and SMC can derive clocks externally from a bank of eight clock signals or a bank of
four baud-rate generators.
20.2 TSA Implementation
The TSA implements both internal route selection and time-division multiplexing (TDM) for multiplexed
serial channels. The TSA supports the serial bus rate and format for most standard TDM buses, including
the T1 and CEPT highways, pulse code modulation (PCM) highway, and ISDN buses in both basic and
primary rates. The two popular ISDN basic rate buses interchip digital link (IDL) and general circuit
interface (GCI, also known as IOM-2) are supported. With two TDM channels, the TSA can
simultaneously support two different TDM frame formats.
TSA programming is independent of the protocol used by the SCC or SMC. The SCCs and SMCs can be
programmed for any synchronous protocol without affecting TSA programming. The TSA simply routes
programmed portions of the received data frame from the TDM pins to the target SCCs and SMCs, while
the target SCC or SMC handles the received data in the actual protocol.
In its simplest mode, the TSA identifies both Rx and Tx frames using one sync pulse and a single clock
signal provided by the user externally. This mode can be enhanced to allow independent routing of Tx and
Rx data on the TDM channel. The user defines the length of a time slot, which need not be limited to 8 bits
or even to a single contiguous position within the frame. For more flexibility, the user can also provide
separate Rx and Tx syncs as well as independent clocks.
ranging from the simplest to the most complex.
20-4
Section 20.3, "NMSI Configuration,"
MPC885 PowerQUICC Family Reference Manual, Rev. 2
features the following:
Figure 20-2 shows example TSA configurations
Freescale Semiconductor