Communication Processor Module
MOTOROLA MPC823e REFERENCE MANUAL 16-347
COMMUNICATION
16
PROCESSOR MODULE
SCCs
TXB—TX Buffer
This bit indicates that a buffer has been transmitted on the Ethernet channel.
RXB—RX Buffer
This bit indicates that a buffer that was not a complete frame was received on the Ethernet
channel.
Figure 16-110. Ethernet Interrupt Events Example
LINE IDLE
STORED IN RX BUFFER
FRAME
RECEIVED IN ETHERNET
TIME
RXD
LINE IDLE
LINE IDLE
STORED IN
TX BUFFER
CLSN
LINE IDLE
TXD
TENA
RXB
TXB
NOTES:
1. RXB event assumes receive buffers are 64 bytes each.
2. The RENA events, if required, must be programmed in the port C parallel I/O, not in the SCC itself.
3. The RXF interrupt may occur later than RENA due to receive FIFO latency.
LEGEND:
P = Preamble, SFD = Start Frame Delimiter, DA and SA = Source/Destination Address, T/L = Type/Length,
D = Data, and CR = CRC bytes.
NOTES:
1. TXB events assume the frame required two transmit buffers.
2. The GRA event assumes a GRACEFUL STOP TRANSMIT command was issued during frame transmission.
3. The TENA or CLSN events, if required, must be programmed in the port C parallel I/O, not in the SCC itself.
ETHERNET SCCE
EVENTS
HDLC SCCE
EVENTS
FRAME
TRANSMITTED BY ETHERNET
DA SA T/L CRD
RXF
P
RENA
SFD DA SA
T/L
CR
D
P
TXB
GRA
SFD
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