User Manual

AT75C220
38
• MPE
Management port enable. Set to one to enable the management port. When zero forces MDIO to high impedance
state.
• CSR
Clear statistics registers. This bit is write-only. Writing a one clears the statistics registers.
• ISR
Increment statistics registers. This bit is write-only. Writing a one increments all the statistics registers by one for test
purposes.
• WES
Write enable for statistics registers. Setting this bit to one makes the statistics registers writable for functional test
purposes.
• BP
Back pressure. If this field is set, then in half-duplex mode collisions are forced on all received frames by transmitting
64 bits of data (default pattern).
MAC Network Configuration Register
Register Name: ETH_CFG
Access Type: Read/write
Reset Value: 0x8
• SPD
Speed. Set to 1 to indicate 100Mbit/sec. operation, 0 for 10Mbit/sec. Has no other functional effect.
• FD
Full duplex. If set to 1, the transmit block ignores the state of collision and carrier sense and allows receive while
transmitting.
• BR
Bit rate. Optional.
• CAF
Copy all frames. When set to 1, all valid frames will be received.
• NBC
No broadcast. When set to 1, frames addressed to the broadcast address of all ones will not be received.
• MTI
Multicast hash enable, when set multicast frames will be received when six bits of the CRC of the destination address
point to a bit that is set in the hash register.
• UNI
Unicast hash enable. When set, unicast frames will be received when six bits of the CRC of the destination address
point to a bit that is set in the hash register.
31 30 29 28 27 26 25 24
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23 22 21 20 19 18 17 16
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15 14 13 12 11 10 9 8
–––RTY CLK EAE BIG
76543210
UNI MTI NBC CAF – BR FD SPD