DS3134 datasheet(118/203 Pages) DALLAS

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DS3134

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- HOST MUST CONFIGURE -

dword 2; Bits 1 & 2 / Buffer Size Select. These bits are controlled by the host to select the manner in

which the Receive DMA will store incoming packet data.

00 = use large size data buffers only

01 = use small size data buffers only

10 = fill a small buffer first followed then by large buffers as needed

11 = illegal state and should not be selected

- HOST MUST CONFIGURE -

dword 2; Bits 3 to 6 / Buffer Offset. These 4 bits are controlled by the host to determine if the packet

data written into the first data buffer should be offset by up to 15 bytes. This allows the host complete

control over the manner in which data will be written into main memory.

0000 (0h) = 0 byte offset from the data buffer address of the first data buffer

0001 (1h) = 1 byte offset from the data buffer address of the first data buffer

1111 (Fh) = 15 byte offset from the data buffer address of the first data buffer

- HOST MUST CONFIGURE -

dword 2; Bits 7 to 9 / Threshold. These 3 bits are controlled by the host to determine when the DMA

should write into the Done Queue that data is available for processing.

000 = DMA should write to the Done Queue only after packet reception is complete

001 = DMA should write to the Done Queue after 1 data buffer has been filled

010 = DMA should write to the Done Queue after 2 data buffers have been filled

011 = DMA should write to the Done Queue after 3 data buffers have been filled

100 = DMA should write to the Done Queue after 4 data buffers have been filled

101 = DMA should write to the Done Queue after 5 data buffers have been filled

110 = DMA should write to the Done Queue after 6 data buffers have been filled

111 = DMA should write to the Done Queue after 7 data buffers have been filled

- FOR DMA USAGE ONLY / HOST CAN ONLY READ THIS FIELD -

dword 2; Bits 10 to 14 / DMA Reserved. Could be any value when read. Should be set to zero when

written to by the Host.

- FOR DMA USAGE ONLY / HOST CAN ONLY READ THIS FIELD -

dword 2; Bit 15 / First Buffer Fill (FBF). This bit will be set to a one by the Receive DMA when it is in

the process of filling the first buffer of a packet. This bit is used by the DMA to know when to switch to

Large Buffers when the Buffer Size Select field is set to 10.

- FOR DMA USAGE ONLY / HOST CAN ONLY READ THIS FIELD -

dword 2; Bits 16 to 28 / Byte Count. The DMA uses these 13 bits to keep track of the number of bytes

stored in the data buffer. Maximum is 8191 bytes (0000h =0 bytes / 1FFFh = 8191 bytes).

DS3134 Datasheet(PDF) 118 Page - Dallas Semiconductor