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Serial Communication Controllers (SCCs)
MC68360 USER’S MANUAL
HBC—Heartbeat Checking
0 = No heartbeat checking is performed. Do not wait for a collision after transmission.
1 = Wait 20 transmit clocks (2
s) for a collision asserted by the transceiver after trans-
mission. The HB bit in the Tx BD is set if the heartbeat is not heard within 20 trans-
mit clocks.
FC—Force Collision
0 = Normal operation.
1 = Force collision. The channel forces a collision on transmission of every transmit
frame. The QUICC should be configured in loopback operation when using this
feature, which allows the QUICC collision logic to be tested by the user. It will result
in the retry limit being exceeded for each transmit frame.
RSH—Receive Short Frames
0 = Discard short frames (less than MINFLR in length)
1 = Receive short frames
IAM—Individual Address Mode
0 = Normal operation. A single 48-bit physical address stored in PADDR1 is checked
on receive.
1 = The individual hash table is used to check all individual addresses that are re-
ceived.
CRC—CRC Selection
00 = Reserved.
01 = Reserved.
10 = 32-Bit CCITT-CRC (Ethernet). (X32 + X26 + X23 + X22 + X16 + X12 + X11 + X10
+ X8 + X7 + X5 + X4 + X2 + X1 +1). Select this to comply with Ethernet specifica-
tions.
11 = Reserved.
PRO—Promiscuous
0 = Check the destination address of the incoming frames.
1 = Receive the frame regardless of its address, unless the RRJCT pin is asserted dur-
ing the frame reception.
BRO—Broadcast Address
0 = Receive all frames containing the broadcast address.
1 = Reject all frames containing the broadcast address unless PRO = 1.
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 max-
imum allowed in the IEEE 802.3 standard. The persistence (P_Per) feature in the
parameter RAM may be used in combination with the SBT bit (or in place of the
SBT bit), if desired.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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