MPC823 datasheet(12/74 Pages) MOTOROLA

12 / 74 page

Communication Processor Module

16-390

MPC823 REFERENCE MANUAL

MOTOROLA

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 16-115. SMCx UART Frame Format

SMTXD

SMCLK

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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