Motorola PowerQUICC II MPC8280 Series Reference Manual page 923

• Independent transmit and receive clocks, unless connected to a TDM channel of an
SIx
• CRC generation and checking
• Full RTS, CTS, and CD signals (supports only one SMSYN signal)
• 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
However, the SMC in transparent mode provides a data character length option of 4 to 16
bits, whereas the SCCs provide 8 or 32 bits, depending on GSMR[RFW]. The SMC in
transparent mode is also referred to as the SMC transparent controller.
28.4.1 Features
The following list summarizes the features of the SMC in transparent mode:
• Flexible data buffers
• Connects to a TDM bus using the TSA in an SIx
• Transmits and receives transparently on its own set of signals using a sync signal 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
28.4.2 SMC Transparent Channel Transmission Process
The transparent transmitter is designed to work with almost no core intervention. When the
core enables the SMC transmitter in transparent mode, it starts sending idles. The SMC
immediately polls the first BD in the transmit channel BD table and once every character
time, depending on the character length (every 4 to 16 serial clocks). When there is a
message to transmit, the SMC fetches the data from memory and starts sending the message
when synchronization is achieved.
Synchronization can be achieved in two ways. First, when the transmitter is connected to a
TDM channel, it can be synchronized to a time slot. Once the frame sync is received, the
transmitter waits for the first bit of its time slot before it starts transmitting. Data is sent only
during the time slots defined by the TSA. Secondly, when working with its own set of
signals, the transmitter starts sending when SMSYNx is asserted.
MOTOROLA
Freescale Semiconductor, Inc.
Chapter 28. Serial Management Controllers (SMCs)
For More Information On This Product,
Go to: www.freescale.com
SMC in Transparent Mode
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