NEC uPD98502 Set RCVDP Set RXE

CHAPTER 5 ETHERNET CONTROLLER
306 Preliminary User’s Manual S15543EJ1V0UM
When the receive frame is complete, Ethernet Controller sets the L-bit in the Receive Descriptor, writes the frame
status bits into the Receive Descriptor, and sets the OWN-bit. Ethernet Controller generates a maskable interrupt,
indicating that a frame has been received and is in memory. Ethernet Controller then waits for a new frame.
Receive procedure is as follows: (Figure 5-8)
Figure 5-8. Receive Procedure
VR4120A Ethernet Controller External PHY Device
Initialize Registers Initialize
Auto Negotiation
Link Configuration
Prepare
Buffer Descriptors
mem
Set
Receive Descriptor
address
Set Receive Enable
Set RCVDP
Set RXE
Decode/Descramble
Exceed RXDRTH
Transfer
Receive Data
mem
If data buffer is full,
get next descriptor
Write RX_Status
and
Read next Descriptor
Generate interrupt
(Receive Done)
mem
Interrupt
Status Check
and
Data Read
End of Frame