
EMAC Registers
1017
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Ethernet Controller
15.6.55 EMACTXPOLLD Register (Offset = 0xC04) [reset = 0x0]
Ethernet MAC Transmit Poll Demand (EMACTXPOLLD)
The MAC Transmit Poll Demand (EMACTXPOLLD) register enables the TX DMA to check whether or not
the DMA owns the current descriptor. The Transmit Poll Demand command is given to wake up the TX
DMA if it is in the suspend mode. The TX DMA can go into the SUSPEND mode because of an underflow
error in a transmitted frame or the unavailability of descriptors owned by it. This Transmit Poll Demand
command can be given at any time and the TX DMA resets this command when it again starts fetching
the current descriptor from host memory.
EMACTXPOLLD is shown in
and described in
Return to
Figure 15-70. EMACTXPOLLD Register
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
TPD
W-0x0
Table 15-80. EMACTXPOLLD Register Field Descriptions
Bit
Field
Type
Reset
Description
31-0
TPD
W
0x0
Transmit Poll Demand. When these bits are written with any value,
the DMA reads the current descriptor pointed to by the MAC Current
Host Transmit Descriptor (EMACHOSTXDESC) register. If that
descriptor is not available (owned by the Host), the transmission
returns to the SUSPEND state and the TU bit of the EMACDMARIS
is asserted. If the descriptor is available, the transmission resumes.