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AT32F435/437
Series Reference Manual
2022.11.11
Page 614
Rev 2.03
0110, 0111: Reserved
Bit 1
MW
0x0
rw
MII Write
When this bit is set, it indicates that the EMAC_MACMIIDT
register is used for a write operation to the PHY.
When this bit is not set, it is a read operation, and the data
is loaded to the EMAC_MACMIIDT register.
Bit 0
MB
0x0
rw
MII Busy
This bit should read a logic 0 before writing to the
EMAC_MACMIIADDR and EMAC_MACMIIDT register.
During a PHY register access, this bit is set to 1’b1 by
software, indicating that a read or write access is in
progress.
The EMAC_MACMIIDT register is invalid before this bit
is cleared by the MAC. Thus, the MII data should be kept
valid until this bit is cleared by the MAC during a PHY write
operation. Similarly, the EMAC_MACMIIDT value is invalid
until this bit is cleared by the MAC during a PHY read
operation.
The previous operation must be completed before
performing subsequent read or write operations. This is
because that there will be no acknowledgement from PHY
to MAC after the completion of a read or write operation,
the function of this bit will not change even if the PHY is
not present.
26.3.6 Ethernet MAC MII data register (EM AC_MACMIIDT)
The Ethernet MAC MII data register stores data to be written to the PHY register located at the address
specified in the EMAC_MACMIIADDR register. EMAC_MACMIIDT register also stores data read out
from the PHY registers.
Bit
Register
Reset value
Type
Description
Bit 31: 16 Reserved
0x0000
resd
Kept at its default value.
Bit 15: 0
MD
0x0000
rw
MII Data
This field contains the 16-bit value from the PHY after a
read operation, or the 16-bit value to be written to the PHY
before a write operation.
26.3.7 Ethernet MAC flow control register (EMAC_MACFCTRL)
The Ethernet MAC flow control register controls the generation and reception of the control frames by
the MAC flow control block. Writing 1 to the Busy bit triggers the flow control block to generate a Pause
frame. The field of the control frame is selected as defined in the 802.3x specification, and the Pause
Time value from this register is used in the Pause Time field of the control frame. The Busy bit remains
set before the control frame is transferred onto the cable. The host must make sure that the Busy bit is
cleared before writing to the register.
Bit
Register
Reset value
Type
Description
Bit 31: 16 PT
0x0000
rw
Pause Time
This field contains the value to be used in the Pause Time
field of the control frame. If the Pause Time bit is
configured to be double-synchronized to the MII clock
domain, then consecutive write operations to this register
should be performed only after at least four clock cycles in
the destination clock domain.
Bit 15: 8
Reserved
0x00
resd
Kept at its default value.
Bit 7
DZQP
0x0
rw
Disable Zero-Quanta Pause
When this bit is set, it disables the automatic generation of
Zero-quanta Pause frame while the flow control signal of
the FIFO layer is disabled.
When this bit is cleared, normal operation resumes. The
automatic generation of Zero-quanta Pause frame is
enabled.
Bit 6
Reserved
0x0
resd
Kept at its default value.
Bit 5: 4
PLT
0x0
rw
Pause Low Threshold