NUC970 Technical Reference Manual
Publication Release Date: Dec. 15, 2015
- 586 -
Revision V1.30
NUC97
0
T
E
CHNIC
A
L
RE
F
E
RE
N
CE
MA
NUA
L
48-bit MAC address defined by registers EMACn_CAM0M and EMACn_CAM0L.
The MGP_WAKE (EMACn_MCMDR[6]) controls if the Magic packet parsing engine enabled. If
MGP_WAKE (EMACn_MCMDR[6]) is high, EMAC will set bit MGPR (EMACn_MISTA[15]) high to
indicate Magic packet received. At the same time, EMAC generates an event to wake system up
from power-down mode. If WOLIEN (EMACn_MIEN[15]) is high, EMAC generates an RX interrupt
to CPU simultaneously.
5.21.6 DMA Descriptors Data Structure
A link-list data structure named as descriptor is used to keep the control, status and data
information of each frame. Through the descriptor, CPU and EMAC exchange the information for
frame reception and transmission.
Two different descriptors defined in EMAC. One named as RXDMA descriptor for frame reception
and the other named as TXDMA descriptor for frame transmission. Each RXDMA or TXDMA
descriptor consists of four words. The descriptor keeps the much control, status information and
the details of descriptor are described below.
RXDMA Descriptor Data Structure
5.21.6.1
The RXDMA descriptor consists of four 32-bit words. The data structure of RXDMA descriptor
shown in figure below.
0
15
31
Reserved
Receive Frame Buffer Starting Address / Time Stamp Least Significant 32-Bit
Receive Frame Status
Receive Frame Byte Count
Next RxDMA Descriptor Starting Address / Time Stamp Most Significant 32-Bit
O
W
N
RXDES 0
RXDES 1
RXDES 2
RXDES 3
Figure 5.21-4 RXDMA Descriptor Data Structure