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Field
Name
R/W
Description
4:2
CR
R/W
Clock Range
The selection of CR clock range determines the frequency of HCLK and
is used to determine the frequency of MDC clock:
Select HCLK MDC clock
000
:
60-100 MHz-HCLK/42
001
:
100-150 MHz-HCLK / 62
010
:
20-35 MHz-HCLK/16
011
:
35-60 MHz-HCLK/26
100
:
150-168 MHz-HCLK/102
101, 110, 111: Reserved
5
Reserved
10:6
MR
R/W
MII Register
These bits select the required register in the selected PHY devices.
15:11
PA
R/W
Physical Layer Address
It indicates which of the 32 possible PHY devices are being accessed.
31:16
Reserved
MII data register (MAC_DATA)
Offset address: 0x14
Reset value: 0x0000 0000
Field
Name
R/W
Description
15:0
MD
R/W
MII Data
The 16-bit data value read from PHY after performing the management
of read operation, or the 16-bit data value written to PHY before
performing the management of write operation.
31:16
Reserved
Receive flow control register (MAC_FCTRL)
Offset address: 0x18
Reset value: 0x0000 0000
Field
Name
R/W
Description
0
FCTRLB/BPA
R/W
Flow Control Busy/Back Pressure Activate
When a pause control frame is initiated in full-duplex mode, this bit
should be read as 0 before it is written to the flow control register.
Only when the application program sets this bit to 1, can a pause
control frame be initialized. During the transmission of the control
frame, this bit continues to be set to indicate that the frame
transmission is in progress. After the transmission of the pause
control frame is completed, the MAC will reset this bit to 0. It cannot
be written to the flow control register before this bit is cleared.
In half-duplex mode, if the TXFCTRLEN bit is set, the back pressure
function will be activated. When this bit is set (and TXFCTRLEN is
set), the back pressure will be declared by the MAC core. During
back pressure period, when the MAC receives a new frame, the
transmitter starts to transmit JAM mode, which causes collision.
When MAC is configured as full-duplex mode, BPA will be
automatically disabled.