MPC8280 datasheet(1254/1386 Pages) FREESCALE

1254 / 1386 page

Fast Ethernet Controller

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

36-20

Freescale Semiconductor

Table 36-8 describes FPSMR fields.

Field HBC

SBT

LPB

LCW FDE MON

—

PRO

FCE

RSH

—

RMII

—

Reset

0000_0000_0000_0000

R/W

Addr

0x11304 (FPSMR1), 0x11324 (FPSMR2)

Field

—

CAM BRO

—

CRC

—

Reset

0000_0000_0000_0000

R/W

Addr

0x11306 (FPSMR1), 0x11326 (FPSMR2)

Figure 36-6. FCC Ethernet Mode Registers (FPSMR

Table 36-8. FPSMR Ethernet Field Descriptions

Bits

Name

Description

HBC

Heartbeat checking

0 No heartbeat checking is performed. Do not wait for a collision after transmission.

1 Wait 40 transmit serial clocks for a collision asserted by the transceiver after transmission.

TxBD[HB] is set if the heartbeat is not heard within 40 transmit serial clocks.

Force collision

0 Normal operation

1 The channel forces a collision on transmission of every transmit frame. The MPC8280 should

be configured in loopback operation when using this feature, which allows the user to test the

MPC8280 collision logic. It causes the retry limit to be exceeded for each transmit frame.

SBT

Stop backoff timer

0 The backoff timer functions normally.

1 The backoff timer (for the random wait after a collision) is stopped whenever carrier sense is

active. In this method, the retransmission is less aggressive than the maximum allowed in the

IEEE 802.3 standard. The persistence (P_PER) feature in the parameter RAM can be used in

combination with the SBT bit (or in place of the SBT bit).

LPB

Local protect bit.

0 Receiver is blocked when transmitter sends (default).

1 Receiver is not blocked when transmitter sends. Must set for full-duplex operation. For external

loopback, GFMR[DIAG] must be programmed also; see Section 30.2, “General FCC Mode

Registers (GFMRx)."

LCW

Late collision window

0 A late collision is any collision that occurs at least 64 bytes from the preamble.

1 A late collision is any collision that occurs at least 56 bytes from the preamble.

FDE

Full duplex Ethernet

0 Disable full-duplex

1 Enable full-duplex. Must be set if FSMR[LPB] is set or external loopback is performed.

MON

RMON mode

0 Disable RMON mode

1 Enable RMON mode

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