Communication Processor Module
MOTOROLA
MPC823e REFERENCE MANUAL
16-393
SMC
COMMUNICATION
16
PROCESSOR MODULE
A serial management controller in UART mode has one feature that an SCCx in UART mode
does not. Data length on an SMCx can be a maximum of 14 bits, whereas, a serial
communication controller only allows 8 bits. A serial management controller in UART mode
is also referred to as a SMCx UART controller.
16.11.6.1 FEATURES.
The following list summarizes the main features of the SMCx in
UART mode:
• 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
16.11.6.2 SMCx UART CHANNEL TRANSMISSION PROCESS.
The UART transmitter is
designed to work with almost no intervention from the core. When the core enables the
SMCx transmitter, it starts transmitting idles. The SMCx UART controller immediately polls
the first buffer descriptor in the transmit channel buffer descriptor ring and once every
character time after that, depending on the character length. When there is a message to
transmit, the SMCx UART controller fetches the data from memory and starts transmitting
the message.
Figure 16-117. SMCx UART Frame Format
SMTXD
SMCLK
16
×
START
BIT
5 TO 14 DATA BITS WITH THE
LEAST-SIGNIFICANT BIT FIRST
PAR.
BIT
OPTIONAL
1 OR 2
STOP BITS
CLOCK NOT TO SCALE
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