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AT32F435/437
Series Reference Manual
2022.11.11
Page 610
Rev 2.03
mode. The MII receive clock input (clk_rx_i) is required for
the loopback mode to work normally, for the transmit clock
is not looped-back internally.
Bit 11
DM
0x0
rw
Duplex Mode
When this bit is set, the MAC operates in full-duplex mode,
in which it can transmit and receive simultaneously.
Bit 10
IPC
0x0
rw
IPv4 Checksum
When this bit is set, the MAC calculates the 16-bit
complement sum of all received Ethernet frames and
enables IPv4 header checksum (assuming it is bytes 26-
26 or 29-30 (VLANtagged)) for received frames, and gives
the status in the receive status information.
The MAC also appends the 16-bit checksum of the
calculated IP header packets (bytes after the
IPv4header ), and adds it to the Ethernet frame that has
been sent out to the application (when Type 2 COE is
deselected).
When this bit is cleared, this feature is disabled.
When this bit is set, IPv4 header checksum feature and
IPv4 or IPv6 TCP, UDP or ICMP payload checksum
feature is enabled while the Type 2 COE is selected. When
this bit is cleared, the COE function in the receiver is
disabled, and the corresponding PCE and IP HCE status
bits are always 0. This bit is reserved (with default value
RO) if the IP checksum mechanism is disabled during the
core configuration.
Bit 9
DR
0x0
rw
Disable Retry
When this bit is set, the MAC attempts only 1 transmission.
When a collision occurs on the MII interface, the MAC will
ignore the current frame transmission and report a frame
abort because of excessive collision error in the transmit
frame status.
When this bit is cleared, the MAC attempts retries based
on the settings of BL ([6: 5]). This bit is applicable only in
half-duplex mode. It is reserved (with default value RO) in
“For full-duplex mode only” mode.
Bit 8
Reserved
0x0
resd
Kept at its default value.
Bit 7
ACS
0x0
rw
Automatic pad/CRC Stripping
When this bit is set, the MAC strips the pad/FCS field on
received frames only when the frame length is shorter than
1536 bytes. All received frame with length field greater
than or equal to 1536 bytes are passed on to the
application without stripping the Pad or FCS field.
When this bit is cleared, the MAC will forward all received
frames to the master without changing its contents.
Bit 6: 5
BL
0x0
rw
Back-off Limit
The Back-off limit defines the random integer number (r)
of slot time delays (512 bit times for 10/100 Mbps) the
MAC waits before retries after a collision. This field is
applicable only in the half-duplex mode. It is reserved (RO)
in “For full-duplex mode only” mode.
00: k= min (n, 10)
01: k = min (n, 8)
10: k = min (n, 4)
11: k = min (n, 1)
Where n = the number of slot time delays for
retransmission attempt, and r takes the random integer
value in the range 0 ≤ r < 2k.
Bit 4
DC
0x0
rw
Deferral Check
When this bit is set, the deferral check function is enabled
in the MAC. The MAC issues a frame abort status and sets
the excessive deferral error flag bit in the transmit frame
status when the transmit state machine is delayed for
more than 24288 bit times in 10/100 Mbit/s mode.
If the Jumbo frame mode is enabled in 10/100 Mbps mode,