MAC configuration register 2.
| FULLDUPLEX | When enabled (set to 1), the MAC operates in Full-Duplex mode. When disabled, the MAC operates in Half-Duplex mode. |
| FLC | FRAMELENGTH CHECKING. When enabled (set to 1), both transmit and receive frame lengths are compared to the Length/Type field. If the Length/Type field represents a length then the check is performed. Mismatches are reported in the StatusInfo word for each received frame. |
| HFEN | HUGE FRAME ENABLEWhen enabled (set to 1), frames of any length are transmitted and received. |
| DELAYEDCRC | DELAYED CRC. This bit determines the number of bytes, if any, of proprietary header information that exist on the front of IEEE 802.3 frames. When 1, four bytes of header (ignored by the CRC function) are added. When 0, there is no proprietary header. |
| CRCEN | CRC ENABLESet this bit to append a CRC to every frame whether padding was required or not. Must be set if PAD/CRC ENABLE is set. Clear this bit if frames presented to the MAC contain a CRC. |
| PADCRCEN | PAD CRC ENABLE. Set this bit to have the MAC pad all short frames. Clear this bit if frames presented to the MAC have a valid length. This bit is used in conjunction with AUTO PAD ENABLE and VLAN PAD ENABLE. See Table 153 - Pad Operation for details on the pad function. |
| VLANPADEN | VLAN PAD ENABLE. Set this bit to cause the MAC to pad all short frames to 64 bytes and append a valid CRC. Consult Table 153 - Pad Operation for more information on the various padding features. Note: This bit is ignored if PAD / CRC ENABLE is cleared. |
| AUTODETPADEN | AUTODETECTPAD ENABLE. Set this bit to cause the MAC to automatically detect the type of frame, either tagged or un-tagged, by comparing the two octets following the source address with 0x8100 (VLAN Protocol ID) and pad accordingly. Table 153 - Pad Operation provides a description of the pad function based on the configuration of this register. Note: This bit is ignored if PAD / CRC ENABLE is cleared. |
| PPENF | PURE PREAMBLE ENFORCEMEN. When enabled (set to 1), the MAC will verify the content of the preamble to ensure it contains 0x55 and is error-free. A packet with an incorrect preamble is discarded. When disabled, no preamble checking is performed. |
| LPENF | LONG PREAMBLE ENFORCEMENT. When enabled (set to 1), the MAC only allows receive packets which contain preamble fields less than 12 bytes in length. When disabled, the MAC allows any length preamble as per the Standard. |
| RESERVED | Reserved. Read value is undefined, only zero should be written. |
| NOBACKOFF | When enabled (set to 1), the MAC will immediately retransmit following a collision rather than using the Binary Exponential Backoff algorithm as specified in the Standard. |
| BP_NOBACKOFF | BACK PRESSURE / NO BACKOFF. When enabled (set to 1), after the MAC incidentally causes a collision during back pressure, it will immediately retransmit without backoff, reducing the chance of further collisions and ensuring transmit packets get sent. |
| EXCESSDEFER | When enabled (set to 1) the MAC will defer to carrier indefinitely as per the Standard. When disabled, the MAC will abort when the excessive deferral limit is reached. |
| RESERVED | Reserved. Read value is undefined, only zero should be written. |