lan9311 Standard Microsystems Corp., lan9311 Datasheet - Page 110

• Manufacturer Part Number: lan9311
• Description: Lan9311/lan9311i Two Port 10/100 Managed Ethernet Switch With 16-bit Non-pci Cpu Interface
• Manufacturer: Standard Microsystems Corp.

Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface
Datasheet
8.5.7
RX Data FIFO Direct PIO Burst Reads
In this mode only A[2:1] are decoded, and any burst read of the LAN9311/LAN9311i will read the RX
Data FIFO. This mode is enabled when FIFO_SEL is driven high during a read access. This is normally
accomplished by connecting the FIFO_SEL signal to a high-order address line. This mode is useful
when the host processor must increment its address when accessing the LAN9311/LAN9311i. Timing
is identical to a PIO burst read, and the FIFO_SEL and END_SEL signals have the same timing
characteristics as the address lines.
In this mode, performance is improved by allowing an unlimited number of back-to-back WORD read
cycles. RX Data FIFO direct PIO burst reads can be performed using chip select (nCS) or read enable
(nRD). An RX Data FIFO direct PIO burst read begins when both nCS and nRD are asserted. Either
or both of these control signals must de-assert between bursts for the period specified in
Table 15.11,
“RX Data FIFO Direct PIO Burst Read Cycle Timing Values,” on page
452. The burst cycle ends when
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
Figure
8.6.
Note: A[1] must toggle during burst reads. Fresh data is supplied each time A[1] is toggled.
Please refer to
Section 15.5.7, "RX Data FIFO Direct PIO Burst Read Cycle Timing," on page 452
for
the AC timing specifications for PIO RX Data FIFO direct PIO burst read operations.
FIFO_SEL
END_SEL
A[x:3]
A[2:1]
nCS, nRD
D[15:0] (OUTPUT)
(READ DATA FROM RX DATA FIFO)
Figure 8.6 Functional Timing for RX Data FIFO Direct PIO Burst Read Operation
Revision 1.2 (04-08-08)
110
SMSC LAN9311/LAN9311i
DATASHEET