Sundance Spas ST201 manual Txdmaburstthresh

Sundance Technology

ST201

PRELIMINARY draft 2

TXDMABURSTTHRESH

Class	I/O Registers, DMA
Base Address	IoBaseAddress register value
Address Offset	0x08
Access Mode	Read/Write
Width	8 bits

TxDMABurstThresh determines the threshold for when the ST201 makes TxDMA bus master requests, based upon the available space in the TxFIFO. The value in TxDMABurstThresh represents free space in the TxFIFO in multiples of 32 bytes. When the free space exceeds the threshold, the ST201 may make a TxDMA request. However, if the free space exceeds the current TxDMAFragLen, ST201 will make TxDMA bus request regardless of whether the free space exceeds the TxDMABurstThresh or not. TxDMABurst- Thresh may be overridden by the TxDMAUrgentThresh mechanism. See the PCI Bus Master Operation section for information about the relationship between TxDMABurstThresh and TxDMAUrgentThresh. A value of zero is invalid. TxDMABurstThresh defaults to 8, a threshold of 256 bytes.

BIT

4..0

7..5

BIT NAME

TxDMABurst- Thresh

Unused

BIT DESCRIPTION

The number of 32-byte words which must be available in the TxFIFO prior to assertion of a TxDMA Burst Request.

These bits are ignored.

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