Communication Processor Module
16-390
MPC823e REFERENCE MANUAL
MOTOROLA
SMC
COMMUNICATION
16
PROCESSOR MODULE
• Other General Parameters—You do not need to access these parameters during
normal operation. They are only listed because they provide helpful debugging
information. Additional parameters are listed in Table 16-33 (page 16-357). The RX and
TX internal data pointers are updated by the SDMA channels to show the next address
in the buffer to be accessed. TCNT is a down-count value that is initialized with the
DATA LENGTH field of the TX buffer descriptor and decremented with every byte read
by the SDMA channels. RCNT is a down-count value that is initialized with the MRBLR
value and decremented with every byte written by the SDMA channels. RSTATE,
TSTATE, RTEMP, TTEMP, and the reserved areas are only used by the RISC
microcontroller.
16.11.5 Disabling the SMCs On-the-Fly
If you do not need a serial management controller, it can be disabled and reenabled later.
In which case, you must follow a particular sequence of steps to ensure that the buffers are
properly closed and that new data is transferred to or from a new buffer. This sequence is
required if the parameters you want to change are not dynamic. If the register or bit
description states that dynamic or on-the-fly changes are allowed, you do not have to follow
the sequence and the register or bit can can be changed immediately.
Note:
To extract data from a partially full receive buffer, use the
CLOSE RX BD
command.
Note:
A serial management controller does not have to be fully disabled for you to
modify the parameter RAM. Refer to the parameter RAM description for details
about modifying the parameter RAM values. If you want to disable the SCCs,
USB, SMCs, SPI, and I
2
C, use the CPM command register (described in
Section 16.2.6.1 CPM Command Register
) to reset the communication
processor module with a single command.
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