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Serial Management Controllers (SMCs)
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MC68360 USER’S MANUAL
BD pointed to by the RBPTR if the Rx BD E-bit is set.
7.11.5.4 SMC RECEIVER SHORTCUT SEQUENCE. A shorter sequence is possible if the
user desires to reinitialize the receive parameters to the state they had after reset. This se-
quence is as follows:
1. Clear the REN bit in the SMCMR.
2. INIT RX PARAMETERS command. Any additional modifications may now be made.
3. Set the REN bit in the SMCMR.
7.11.5.5 SWITCHING PROTOCOLS. Sometimes the user desires to switch the protocol
that the SMC is executing (for instance, UART to Transparent) without resetting the board
or affecting any other SMC. This can be accomplished using only one command and a short
number of steps:
1. Clear the TEN and REN bits in the SMCMR.
2. INIT TX AND RX PARAMETERS command. This one command initializes both trans-
mit and receive parameters. Any additional modifications may now be made in the SM-
CMR to change the protocol, etc.
3. Set the SMCMR TEN and REN bits. The SMC is enabled with the new protocol.
7.11.6 Saving Power
When the TEN and REN bits of an SMC are cleared, that SMC consumes a minimal amount
of power.
7.11.7 SMC as a UART
The following paragraphs describe the use of the SMC as a UART.
7.11.7.1 SMC UART KEY FEATURES. The SMC UART contains the following key fea-
tures:
Flexible Message-Oriented Data Structure
Programmable Data Length (5–14 Bits)
Programmable 1 or 2 Stop Bits
Even/Odd/No Parity Generation and Checking
Frame Error, Break, and IDLE Detection
Transmit Preamble and Break Sequences
Received Break Character Length Indication
Continuous Receive and Transmit Modes
7.11.7.2 SMC UART COMPARISON. As compared to the UART modes supported by the
SCCs, the SMCs generally offer less functionality and performance. This fits with their pur-
pose of providing simple debug/monitor ports rather than full-featured UARTs. The SMC
UARTs do not support the following features:
RTS, CTS, and CD Pins
Receive and Transmit Sections Being Clocked at Different Rates
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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