Ethernet Rxbds - Motorola MPC8260 PowerQUICC II User Manual

Frame
Received in Ethernet
Time
RXD Line Idle
RX_DV
Ethernet FCCE
Events
Notes
:
1. RXB event assumes receive buffers are 64 bytes each.
2. The RXF interrupt may occur later than RX_DV due to receive FIFO latency.
Frame
Transmitted by Ethernet
TXD Line Idle
TX_EN
COL
Ethernet FCCE
Events
Notes:
1. TXB events assume the frame required two transmit buffers.
2. The GRA event assumes a
Legend:
P = Preamble, SFD = Start frame delimiter, DA and SA = Destination/Source address,
T/L = Type/Length, D = Data, CR = CRC bytes
Figure 30-7. Ethernet Interrupt Events Example
Note that the FCC status register is not valid for the Ethernet protocol. The current state of
the MII signals can be read through the parallel ports.

30.19 Ethernet RxBDs

The Ethernet controller uses the RxBD to report information about the received data for
each buffer. Figure 30-8 shows the FCC Ethernet RxBD format.
MOTOROLA
Stored in Rx Buffer
P SFD DA SA T/L
Stored in Tx Buffer
P SFD DA SA T/L
TXB
command was issued during frame transmission.
GRACEFUL STOP TRANSMIT
Chapter 30. Fast Ethernet Controller
Part IV. Communications Processor Module
D CR Line Idle
RXB RXF
D CR
Line Idle
TXB, GRA
30-23