MPC823 datasheet(9/74 Pages) MOTOROLA

9 / 74 page

Communication Processor Module

MOTOROLA

MPC823 REFERENCE MANUAL

16-387

• 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 16-354). 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 I2C, 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.

MPC823 데이터시트(PDF) 9 Page - Motorola, Inc