Network Card User Manual

www.ti.com Ethernet Media Access Controller (EMAC) Registers
5.46 Transmit Channel 0-7 DMA Head Descriptor Pointer Register (TXnHDP)
The transmit channel 0-7 DMA head descriptor pointer register (TXnHDP) is shown in Figure 85 and
described in Table 83.
Figure 85. Transmit Channel n DMA Head Descriptor Pointer Register (TXnHDP)
31 16
TXnHDP
R/W-x
15 0
TXnHDP
R/W-x
LEGEND: R/W = Read/Write; -n = value after reset; -x = value is indeterminate after reset
Table 83. Transmit Channel n DMA Head Descriptor Pointer Register (TXnHDP)
Field Descriptions
Bit Field Value Description
31-0 TXnHDP 0-FFFF FFFFh Transmit channel n DMA Head Descriptor pointer. Writing a transmit DMA buffer descriptor
address to a head pointer location initiates transmit DMA operations in the queue for the
selected channel. Writing to these locations when they are nonzero is an error (except at reset).
Host software must initialize these locations to 0 on reset.
5.47 Receive Channel 0-7 DMA Head Descriptor Pointer Register (RXnHDP)
The receive channel 0-7 DMA head descriptor pointer register (RXnHDP) is shown in Figure 86 and
described in Table 84.
Figure 86. Receive Channel n DMA Head Descriptor Pointer Register (RXnHDP)
31 16
RXnHDP
R/W-x
15 0
RXnHDP
R/W-x
LEGEND: R/W = Read/Write; -n = value after reset; -x = value is indeterminate after reset
Table 84. Receive Channel n DMA Head Descriptor Pointer Register (RXnHDP)
Field Descriptions
Bit Field Value Description
31-0 RXnHDP 0-FFFF FFFFh Receive channel n DMA Head Descriptor pointer. Writing a receive DMA buffer descriptor
address to this location allows receive DMA operations in the selected channel when a channel
frame is received. Writing to these locations when they are nonzero is an error (except at reset).
Host software must initialize these locations to 0 on reset.
121
SPRUFI5B–March 2009–Revised December 2010 Ethernet Media Access Controller (EMAC)/Management Data Input/Output
(MDIO)
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