Buffer 1 Address Pointer
These bits indicate the physical address of Buffer 1. There are no limitations on the buffer address alignment except for the following condition: The DMA uses the configured value for its address generation when the RDES2 value is used to store the start of frame. Note that the DMA performs a write operation with the RDES2[2:0] bits as 0 during the transfer of the start of frame but the frame data is shifted as per the actual Buffer address pointer. The DMA ignores RDES2[2:0] (corresponding to bus width of 64) if the address pointer is to a buffer where the middle or last part of the
frame is stored.
Receive Descriptor 3 (RDES3)
RDES3 contains the address pointer either to the second data buffer in the descriptor or to the next descriptor.
Table 41-6 Receive Descriptor 3
Bit
Description
31:0
Buffer 2 Address Pointer (Next Descriptor Address)
These bits indicate the physical address of Buffer 2 when a descriptor ring structure is used. If the Second Address Chained (RDES1[24]) bit is set, this address contains the pointer to the physical memory where the
Next Descriptor is present.
If RDES1[24] is set, the buffer (Next Descriptor) address pointer must be bus
width-aligned (RDES3[2:0] = 0, corresponding to a bus width of 64. LSBs are ignored internally.) However, when
RDES1[24] is reset, there are no limitations on the RDES3 value, except for the following condition: The DMA uses the configured value for its buffer address generation when the RDES3 value is used to store the start of frame. The DMA ignores RDES3[2:0] (corresponding to a bus width of 64) if the address pointer is to a buffer
where the middle or last part of the frame is stored.
