Motorola MPC8260 User Manual
MOTOROLA
Chapter 30. Fast Ethernet Controller
30-23
Part IV. Communications Processor Module
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.
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.
each buffer. Figure 30-8 shows the FCC Ethernet RxBD format.
RXB
Line Idle
Stored in Rx Buffer
RXD
RX_DV
Frame
Received in Ethernet
Time
Line Idle
TXD
TX_EN
Frame
Transmitted by Ethernet
COL
TXB, GRA
TXB
Line Idle
Line Idle
Stored in Tx Buffer
Notes
:
Ethernet FCCE
Events
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.
2. The RXF interrupt may occur later than RX_DV due to receive FIFO latency.
Notes:
Ethernet FCCE
Events
1. TXB events assume the frame required two transmit buffers.
2. The GRA event assumes a
2. The GRA event assumes a
GRACEFUL
STOP
TRANSMIT
command was issued during frame transmission.
P SFD DA SA
CR
RXF
T/L
D
P SFD DA SA
CR
T/L
D
Legend:
P = Preamble, SFD = Start frame delimiter, DA and SA = Destination/Source address,
T/L = Type/Length, D = Data, CR = CRC bytes
T/L = Type/Length, D = Data, CR = CRC bytes