DS31256_V01 datasheet(96/183 Pages) MAXIM

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DS31256 256-Channel, High-Throughput HDLC Controller

96 of 183

RDMAQ

Receive DMA Queues Control

0780h

Bit #

Name

n/a

RDQF

RDQFE

RFQSF

RFQLF

n/a

RFQFE

Default

Bit #

Name

n/a

RDQT2

RDQT1

RDQT0

Default

Note: Bits that are underlined are read-only; all other bits are read-write.

Bit 0/Receive Free-Queue FIFO Enable (RFQFE). To enable the DMA to burst read descriptors from the free

queue, this bit must be set to 1. If this bit is set to 0, descriptors are read one at a time.

0 = free-queue burst read disabled

1 = free-queue burst read enabled

Bit 2/Receive Free-Queue Large Buffer FIFO Flush (RFQLF). When this bit is set to 1, the internal large

buffer free-queue FIFO is flushed (currently loaded free-queue descriptors are lost). This bit must be set to 0 for

proper operation.

0 = FIFO in normal operation

1 = FIFO is flushed

Bit 3/Receive Free-Queue Small Buffer FIFO Flush (RFQSF). When this bit is set to 1, the internal small

buffer free-queue FIFO is flushed (currently loaded free-queue descriptors are lost). This bit must be set to 0 for

proper operation.

0 = FIFO in normal operation

1 = FIFO is flushed

Bit 4/Receive Done-Queue FIFO Enable (RDQFE). See Section 9.2.4 for details.

Bit 5/Receive Done-Queue FIFO Flush (RDQF). See Section 9.2.4 for details.

Bits 8 to 10/Receive Done-Queue Status Bit Threshold Setting (RDQT0 to RDQT2). See Section 9.2.4 for

details.

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