Motorola MPC823e Reference Manual page 776

Communication Processor Module
Figure 16-108 illustrates the basic components and pins required to make the Ethernet
connection between the MPC823e and EEST.
MPC823e
MPC823
SCCx TXDx
TENA (RTSx)
TCLK (CLKx)
RENA (CDx)
RCLK (CLKx)
CLSN (CTSx)
PARALLEL I/O
START
PREAMBLE FRAME
DELIMITER
7 BYTES 1 BYTE
NOTE: The MPC82x automatically pads the short transmit frames.
Figure 16-107. Connecting the MPC823e to Ethernet
The following pins function differently when a serial communication controller is in Ethernet
mode than when it is in other protocols:
• Transmit Enable (TENA)—The RTSx pin changes to TENA when a serial
communication controller is in Ethernet mode. The polarity of TENA is active high,
whereas the polarity of RTSx is active low.
• Receive Enable (RENA)—The CDx pin changes to RENA when a serial communication
controller is in Ethernet mode. The polarity of RENA is active high, whereas the polarity
of CDx is active low.
• Collision (CLSN)—The CTSx pin changes to CLSN when a serial communication
controller is in Ethernet mode. The polarity of CLSN is active high, whereas the polarity
of CTSx is active low.
Note: The carrier sense signal is referenced in Ethernet descriptions because it
indicates when the LAN is being used. Carrier sense is defined as RENA OR'ed
with CLSN.
16-322
EEST
MC68160
TX
TENA
TCLK
RXDx RX
RENA
RCLK
CLSN
LOOP
DEST SOURCE TYPE/
ADDR LENGTH
ADDR
6 BYTES 6 BYTES 2 BYTES
STORED IN TRANSMIT BUFFER
STORED IN RECEIVE BUFFER
MPC823e REFERENCE MANUAL
RJ-45
TWISTED PAIR
D-15
AUI
FRAME
CHECK
DATA
SEQUENCE
46–1500 BYTES 4 BYTES
MOTOROLA