Motorola MPC823e Reference Manual page 636

Communication Processor Module
16.9.7 SCCx Parameter RAM Memory Map
The serial communication controller parameter RAM area begins at an offset from the SCCx
base area. The protocol-specific portions of the SCCx parameter RAM are discussed in the
specific protocol descriptions and the part that is common to all serial communication
controller protocols is shown in Table 16-24.
You must initialize certain parameter RAM values before enabling the serial communication
controllers. Other values are initialized or written by the communication processor module.
Once initialized, most parameter RAM values do not need to be accessed in your software
because most of the activity is centered around the transmit and receive buffer descriptors,
not the parameter RAM. However, if you do access the parameter RAM, the following
regulations must be noted:
• The parameter RAM can be read at any time.
• The parameter time values related to the SCCx transmitter can only be written
whenever the transmitter is disabled after a STOP TRANSMIT command and before a
RESTART TRANSMIT command or after the buffer/frame finishes transmitting as a
result of the execution of a GRACEFUL STOP TRANSMIT command and before a
RESTART TRANSMIT command is executed.
• The parameter RAM values related to the SCCx receiver can only be written when the
receiver is disabled.
Refer to Section 16.9.14 Disabling the SCCs On-the-Fly for more information.
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