Smc Features - Freescale Semiconductor MPC850 User Manual

SMC Features

The receive data source can be L1RXDa if the SMC is connected to the TDM channel of
the SI or SMRXD if it is connected to the NMSI. Likewise, the transmit data source can be
L1TXDa if using the TDM or SMTXD if using the NMSI. However, if SMC2 is connected
to the NMSI, the TDM channel is unavailable since SMC2 shares its dedicated pins with
L1TXDa and L1RXDa.
If the SMC is connected to the TDM, the SMC receive and transmit clocks can be
independent from each other, as defined in Chapter 20, "Serial Interface." However, if the
SMC is connected to the NMSI, receive and transmit clocks must be connected to a single
clock source (SMCLK), an internal signal name for a clock generated from the bank of
clocks. SMCLK originates from an external pin or one of the four internal BRGs. See
Section 20.3, "NMSI Configuration."
An SMC connected to the TDM derives a synchronization pulse from the TSA. An SMC
connected to the NMSI using transparent protocol can use SMSYN for synchronization to
determine when to start a transfer. SMSYN is not used when the SMC is in UART mode.
30.1 SMC Features
The following is a list of the SMC's main features:
• Each SMC can implement the UART protocol on its own pins
Each SMC can implement a totally transparent protocol on a multiplexed (TDM) or
nonmultiplexed (NMSI) line. The transparent mode can also be used for a fast connection
between MPC850s. However, if SMC2 is connected to the NMSI, the TDM channel is
unavailable.
• Each SMC channel fully supports the C/I and monitor channels of the GCI (IOM-2)
in ISDN applications
U Bus
Control
Registers
Peripheral Bus
Rx
Data
Register
RXD
Shifter
Figure 30-1. SMC Block Diagram
MPC850 Family User's Manual
SYNC
Control
Logic
CLK
Tx
Data
Register
TXD
Shifter