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Communication Processor Module
MOTOROLA
MPC823 USER’S MANUAL
16-399
SMC
COMMUNICATION
16
PROCESSOR
MODULE
16.11.7 The SMC in Transparent Mode
The SMC in Transparent mode is also referred to as the SMC Transparent controller. The
following is a list of the features that the SMC Transparent controller does not support:
Independent transmit and receive clocks, unless connected to a TDM channel of the
serial interface
CRC generation and checking
Full RTS, CTS, and CD pins. Instead, there is a SMSYN pin for each SMC.
Ability to transmit data on demand using the TODR
Receiver/transmitter in transparent mode while executing another protocol
4-, 8-, or 16-bit Sync recognition
Internal DPLL support
The SMC in Transparent mode provides one feature that the SCC2 in Transparent mode did
not. The serial management controllers allow a data character length option of 4 to 16 bits,
whereas the SCC2 provides 8 or 32 bits, depending on how the RFW bit is set in the
16.11.7.1 FEATURES. The following list summarizes the features of the SMC in
Transparent mode:
Flexible data buffers
Connects to a TDM bus using the time-slot assigner in the serial interface
Transmits and receives transparently on its own set of pins using a sync pin to
synchronize the beginning of transmission and reception to an external event
Programmable character length (4-16)
Reverse data mode
Continuous transmission and reception modes
Four commands
16.11.7.2 SMC TRANSPARENT CHANNEL TRANSMISSION PROCESS. The SMC
Transparent transmitter is designed to work with almost no intervention from the core. When
the core enables the SMC transmitter in transparent mode, it starts transmitting idles. The
serial management controllers immediately poll the first buffer descriptor in the transmit
channel buffer descriptor ring and once every character time, depending on the character
length (every 4 to 16 serial clocks). When there is a message to transmit, a serial
management controller fetches the data from memory and starts transmitting the message
once synchronization is achieved.