8.2.166 GMAC Express MAC Network Configuration Register

GRXER has no effect on the GMAC's operation when GRXDV is low. Set this bit when using the RGMII wrapper in Half Duplex mode.

Rejects frames with non-standard preamble.

Accepts frames with non-standard preamble.

The transmit IPG cannot be increased.

The transmit IPG can be increased above 96 bit times depending on the previous frame length using the IPG Stretch Register.

Normal operation, frames with FCS/CRC errors are rejected.

Frames with FCS/CRC errors are rejected. FCS error statistics are still collected for frames with bad FCS and FCS status is recorded in frame’s DMA descriptor.

Disables frames to be received in Half Duplex mode while transmitting.

Enables frames to be received in Half Duplex mode while transmitting.

Disables the receive checksum engine. Frames with bad IP, TCP or UDP checksums are accepted.

Enables the receive checksum engine. Frames with bad IP, TCP or UDP checksums are discarded.

Copies pause frames to the system memory.

Prevents valid pause frames being copied to memory. Pause frames are not copied to memory regardless of the state of the Copy All Frames bit, whether a hash match is found or whether a type ID match is identified. If a destination address match is found, the pause frame will be copied to memory. Note that valid pause frames received will still increment pause statistics and pause the transmission of frames as required.

MCK divided by 8 (MCK up to 20 MHz)

MCK divided by 16 (MCK up to 40 MHz)

MCK divided by 32 (MCK up to 80 MHz)

MCK divided by 48 (MCK up to 120 MHz)

MCK divided by 64 (MCK up to 160 MHz)

MCK divided by 96 (MCK up to 240 MHz)

Includes the received frame check sequence (last 4 bytes) when writing to memory.

Excludes the received frame check sequence (last 4 bytes) when writing to memory. The frame length indicated will be reduced by four bytes in this mode.

Accepts frames with a measured length shorter than the extracted length field

Discards frames with a measured length shorter than the extracted length field (as indicated by bytes 13 and 14 in a non-VLAN tagged frame). This only applies to frames with a length field less than 0x0600.

Does not pause the transmission when a non-zero 802.3 classic pause frame is received.

Pauses transmission when a non-zero 802.3 classic pause frame is received and PFC has not been negotiated.

Normal operation.

The backoff between collisions will always be one slot time and helps test the too many retries condition. Also used in the pause frame tests to reduce the pause counter's decrement time from 512 bit times, to every GRXCK cycle.

Operates in 10/100 Mbps mode.

Operates in Gigabit mode.

Rejects frame sizes above 1518 bytes.

Accepts frames up to 1536 bytes in length. Normally the GMAC would reject any frame above 1518 bytes.

Rejects unicast frames.

Accepts unicast frames when the 6-bit hash function of the destination address points to a bit that is set in the Hash register.

Rejects multicast frames.

Accepts multicast frames when the 6-bit hash function of the destination address points to a bit that is set in the Hash register.

Accepts broadcast frames.

Rejects frames addressed to the broadcast address of all ones.

Discards invalid frames.

Accepts all valid frames.

Disables jumbo frames.

Enables jumbo frames up to 16383 bytes to be accepted. The default length is 10240 bytes.

Passes all frames to address matching logic

Passes only VLAN tagged frames to the address matching logic.

Half-duplex mode.

The transmit block ignores the state of collision and carrier sense and allows receive while transmitting.

MAC operates at 10 Mbps.

MAC operates at 100 Mbps.