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Serial Communication Controllers (SCCs)
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MC68360 USER’S MANUAL
Figure 7-68. QUICC Ethernet Serial CAM Interface
The CAM control logic uses RSTRT, in combination with the RXD and RCLK signals, to
store the destination address, source address, etc. and generate writes to the CAM for
address recognition. In addition, the RENA signal supplied from the EEST may be used to
abort the comparison if a collision occurs on the receive frame.
After the comparison occurs, the CAM control logic asserts the receive reject (RRJCT) pin,
if the current receive frame should be rejected. The QUICC Ethernet controller will then
immediately stop writing data to system memory and will reuse the buffer(s) for the next
frame. If the CAM wishes to accept the frame, the CAM control logic does nothing (RRJCT
is not asserted). If RRJCT is asserted, it must be asserted prior to the end of the receive
frame.
QUICC
SCC
TENA (RTS)
TCLK (CLKx)
RxD
RENA (CD)
RCLK (CLKx)
CLSN (CTS)
RSTRT
RRJCT
PARALLEL I/O
TX
TENA
TCLK
RX
RENA
RCLK
CLSN
LOOP
PASSIVE
EEST
MC68160
TO MEDIA
SHIFT REGISTER
AND
CAM CONTROL
CAM
BUFFERS
NOTE: The receive data is sent directly from the EEST serial interface to the CAM using RXD and RCLK. RSTRT is asserted
at the beginning of the destination address. RRJCT should be asserted during the frame to cause the frame to be rejected.
The system bus is used for CAM initialization and maintenance.
SYSTEM BUS
PREAMBLE
FRAME
CHECK
SEQUENCE
START
FRAME
DELIMITER
7 BYTES
46–1500 BYTES
DEST.
ADDR.
SOURCE
ADDR.
6 BYTES
2 BYTES
TYPE/
LENGTH
6 BYTES
RSTRT
RRJCT
RXD
FRAME REJECTED IF ASSERTED DURING FRAME RECEPTION.
FURTHER TRANSMISSIONS ON SYSTEM BUS CEASE, AND
BUFFER DESCRIPTORS ARE REUSED.
PB15–PB8
DATA
OPTIONAL
FRAME TAG
BYTE
ASSERTED ON SECOND DESTINATION
ADDRESS BIT FOR A DURATION OF ONE
BIT TIME.
SDACK2–SDACK1
1 BYTE
4 BYTES
TxD
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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