RM0319 datasheet(145/368 Pages) STMICROELECTRONICS

tên linh kiện	RM0319

Giải thích chi tiết về linh kiện	SPEAr320S architecture and functionality

PDF	368 Pages

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RM0319

Fast Ethernet port (MII0)

Doc ID 022640 Rev 3

145/368

Figure 45.

DMA descriptor list: ring structure (left) and chain structure (right).

Note:

The descriptor addresses must be aligned to the bus-width used (32/64/128 bit buses).

Transmit descriptors

As shown in Figure 46, there are four different transmit descriptors:

●

Transmit Descriptor 0, TDES0 (Table 44): it contains the status of the transmitted frame

and the descriptor ownership information along with control bits for controlling the

descriptor structure and the frame being transferred.

●

Transmit Descriptor 1, TDES1 (Table 45): it contains the data buffer sizes.

●

Transmit Descriptor 2, TDES2 (Table 46): it contains the address pointer to the first

data buffer in the descriptor.

●

Transmit Descriptor 3, TDES3 (Table 47): it contains the address pointer to the second

data buffer in the descriptor or the next descriptor (in case of chained structure).

Buffer 1

Descriptor 0

Descriptor 1

Descriptor 2

Descriptor n

Buffer 2

Buffer 1

Buffer 2

Buffer 1

Descriptor 0

Descriptor 1

Descriptor 2

Next Descriptor

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