LAN9420 Datasheet, PDF (106/171 Pages) SMSC Corporation – Single-Chip Ethernet Controller with HP Auto-MDIX Support and PCI Interface

4.3.2
Single-Chip Ethernet Controller with HP Auto-MDIX Support and PCI Interface
Datasheet
Transmit Poll Demand Register (TX_POLL_DEMAND)
Offset:
0004h
Size:
32 bits
This register enables the TX DMA engine to check for new descriptors.
BITS
31:0
DESCRIPTION
Transmit Poll Demand (TPD)
When written with any value, the DMAC will check for frames to be
transmitted. If no descriptor is available, the transmit process returns to the
suspended state and bit 2 of the DMAC_STATUS register (transmit buffer
unavailable - TU) is not asserted. A write to this register is only effective if
the transmit process is in the suspended state. A Read of this register will
timeout and invalid data will be returned.
TYPE
WO
DEFAULT
-
Revision 1.6 (07-18-11)
106
DATASHEET
SMSC LAN9420/LAN9420i