NEC Network Controller uPD98502 - Manual (Page 295)

CHAPTER 5 ETHERNET CONTROLLER
Preliminary User’s Manual S15543EJ1V0UM 295
5.2.27 En_TXFCR (Transmit FIFO Control Register)
Bits Field R/W Default Description
31:16 TPTV R/W FFFFH Transmit Pause Timer Value:
15:10 TX_DRTH R/W 10H Transmit Drain Threshold Level:
This threshold is enable to the transmit data to the MAC Control Block form
the Tx-FIFO. If the transfer data is not completed by DMAC and the buffer
empty pointer exceed this pointer, this MAC Control Block sends an Abort
Packet. Please see the Figure 5-2. This is a word pointer.
9:8 Reserved R/W 0 Reserved for future use. Write 0s.
7:2 TX_FRTH R/W 30H Transmit Fill Threshold Level:
This threshold is enable to transmit data to the FIFO from the internal bus
through the DMAC of this block. Please see the Figure 5-2. This is a word
pointer.
1:0 Reserved R/W 0 Reserved for future use. Write 0s.
Figure 5-2. Tx FIFO Control Mechanism
FLTH DRTH
FLTH DRTH
Request
New data
FLTH DRTH
Tx_FIFO (256 Bytes)
FLTH DRTH
EOF
Request
New data
Request
New data
Sending
Abort
Finish
Packet
Transmit
To MAC Control Block From internal bus