MPC8280 datasheet(805/1386 Pages) FREESCALE

805 / 1386 page

SCC Ethernet Mode

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

25-17

Data length and buffer pointer fields are described in Section 20.2, “SCC Buffer Descriptors (BDs).” Data

length includes the total number of frame octets (including four bytes for CRC).

Last in frame. The Ethernet controller sets this bit when this buffer is the last one in a frame, which

occurs when the end of a frame is reached or an error is received. In the case of error, one or more

of the CL, OV, CR, SH, NO, and LG bits are set. The Ethernet controller writes the number of frame

octets to the data length field.

0 The buffer is not the last one in a frame.

1 The buffer is the last one in a frame.

First in frame. The Ethernet controller sets this bit when this buffer is the first one in a frame.

0 The buffer is not the first one in a frame.

1 The buffer is the first one in a frame.

—

Reserved, should be cleared.

Miss. (valid only if L = 1) The Ethernet controller sets M for frames that are accepted in promiscuous

mode, but are flagged as a miss by internal address recognition. Thus, in promiscuous mode, M

determines whether a frame is destined for this station.

0 The frame is received because of an address recognition hit.

1 The frame is received because of promiscuous mode.

8–9

—

Reserved, should be cleared.

Rx frame length violation. Set when a frame length greater than the maximum defined for this

channel has been recognized. Only the maximum number of bytes allowed is written to the buffer.

Rx nonoctet-aligned frame. Set when a frame containing a number of bits not divisible by eight is

received. Also, the CRC check that occurs at the preceding byte boundary generated an error.

Short frame. Set if a frame smaller than the minimum defined for this channel was recognized.

Occurs if PSMR[RSH] = 1.

Rx CRC error. set when a frame contains a CRC error.

Overrun. Set when a receiver overrun occurs during frame reception.

Collision. This frame is closed because a collision occurred during frame reception. CL is set only if

a late collision occurs or if PSMR[RSH] is enabled. Late collisions are better defined in PSMR[LCW].

Table 25-7. SCC Ethernet RxBD Status and Control Field Descriptions (continued)

Bits

Name

Description

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