lan9312 Standard Microsystems Corp., lan9312 Datasheet - Page 106

• Manufacturer Part Number: lan9312
• Description: Lan9312 High Performance Two Port 10/100 Managed Ethernet Switch With 32-bit Non-pci Cpu Interface
• Manufacturer: Standard Microsystems Corp.

Revision 1.2 (04-08-08)
8.4.4
D[31:0] (OUTPUT)
PIO Reads
PIO reads can be used to access System CSR’s or RX Data and RX/TX Status FIFOs. PIO reads can
be performed using Chip Select (nCS) or Read Enable (nRD). A PIO Read cycle begins when both
nCS and nRD are asserted. Either or both of these control signals must de-assert between cycles for
the period specified in
either or both nCS and nRD are de-asserted. They may be asserted and de-asserted in any order.
Read data is valid as indicated in the functional timing diagram in
The endian select signal (END_SEL) has the same timing characteristics as the address lines.
Please refer to
for PIO read operations.
Note: Some registers have restrictions on the timing of back-to-back write-read cycles. Please refer
END_SEL
nCS, nRD
to
Section 8.4.2
A[x:2]
Section 15.5.4, "PIO Read Cycle Timing," on page 447
Figure 8.3 Functional Timing for PIO Read Operation
Table 15.8, “PIO Read Cycle Timing Values,” on page
for information on these restrictions.
High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface
DATASHEET
106
VALID
VALID
VALID
Figure
for the AC timing specifications
8.3.
447. The cycle ends when
SMSC LAN9312
Datasheet