16.13.6 The I
C Buffer Descriptor Ring
2
The data associated with the I
buffer descriptors organized in a buffer descriptor ring located in the dual-port RAM. This
ring has the same basic configuration as the serial communication and serial management
controllers.
The buffer descriptor ring forms a circular queue that helps you organize the buffers you
want to transmit or receive. Using the buffer descriptors, the communication processor
module confirms reception and transmission or indicates error conditions so that the
processor knows the buffers have been serviced. The actual buffers can reside in either
external or internal memory and the data buffers can reside in the parameter RAM area of
another controller if it is not enabled.
DUAL-PORT RAM
TX DATA BUFFER
POINTER TO I2C
TX RING
POINTER TO I2C
RX RING
MOTOROLA
2
C controller is stored in buffers, which are referenced by
TX BUFFER DESCRIPTOR RING
FRAME STATUS
DATA LENGTH
DATA POINTER
RX BUFFER DESCRIPTOR RING
FRAME STATUS
DATA LENGTH
DATA POINTER
2
Figure 16-132. I
C Memory Format
MPC823e REFERENCE MANUAL
Communication Processor Module
EXTERNAL MEMORY
TX DATA BUFFER
RX DATA BUFFER
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