W89C940 Datasheet, PDF (25/61 Pages) Winbond – ELANC-PCI (TWISTED-PAIR ETHER-LAN CONTROLLER WITH PCI INTERFACE)

W89C940
EIR_THD
[15:0]
CLDA0[7:0]
CLDA1[7:0]
Page 3
Base+06h
[15:0]
Page 0
Base+01h[7:0]
Base+02h[7:0]
Early Interrupt Threshold Register: Word Read/Write
Early Interrupt Threshold is in the unit of byte. The minimum
value of threshold is 64 bytes. Any value less than 64 bytes will
be treated as 64 bytes except value 0000h. Not to program
threshold or program 0000h will be disable Early Interrupt
function. The initial threshold value after Power-on Reset is
0000h.
Current Local DMA Address Register: Read only.
Currrent Address of Local DMA. Use word IO read command to
access the content. Initial value after Power-on Reset is 0000h.
Using word command to read port base+01h will have both
CLDA0 & CLDA1.
3. Program Procedure:
a. Set EIR_EN=1 to enable Eraly Interrupt Function and set EIR_MASK=1 to enable interrupt pin
INTA# of PCI local bus.
b. Program eraly interrupt threshold, EIR_THD.
c. Set DCR not in Loopback mode.
d. Set RCR not in monitor mode.
e. Program CR to start receive packet.
f. Wait until a frame with a correct destination address and receive byte count greater than Early
interrupt Threshold.
g. An intrrupt initiated and EIR_STATUS register set.
ps: a, b, c, d & e can also be programmed individually.
PCI BUS TRANSACTION
This section will introduce the Read Transaction, Write Transaction, and Termination Transaction of PCI bus.
Read Transaction ( I/O and Memory Read )
The timing of read transaction is shown in figure.
25