Highly Efficient Single-Chip 10/100 Ethernet Controller with HP Auto-MDIX
Datasheet
6.5
RX Data FIFO Direct PIO Burst Reads
In this mode the upper address inputs are not decoded, and any burst read of the LAN9215 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 LAN9215. Timing
is identical to a PIO Burst Read, and the FIFO_SEL signal has the same timing characteristics as the
address lines.
In this mode, performance is improved by allowing an unlimited number of back-to-back DWORD or
WORD read cycles. RX Data FIFO Direct PIO Burst Reads can be performed using Chip Select (nCS)
or Read Enable (nRD). When either or both of these control signals go high, they must remain high
for the period specified.
Note that address lines A[2:1] are still used, and address bits A[7:3] are ignored.
FIFO_SEL
A[2:1]
nCS, nRD
Data Bus
Figure 6.4 RX Data FIFO Direct PIO Burst Read Cycle Timing
Note: The “Data Bus” width is 16 bits.
Table 6.6 RX Data FIFO Direct PIO Burst Read Cycle Timing
SYMBOL
DESCRIPTION
MIN
TYP
MAX
UNITS
tcsh
tcsdv
tacyc
tasu
tadv
tah
nCS, nRD Deassertion Time
nCS, nRD Valid to Data Valid
Address Cycle Time
13
ns
ns
30
165
0
Address, FIFO_SEL Setup to nCS, nRD Valid
Address Stable to Data Valid
Address, FIFO_SEL Hold Time
Data Buffer Turn On Time
ns
40
7
0
0
ns
ns
ns
ns
tdon
tdoff
tdoh
Data Buffer Turn Off Time
Data Output Hold Time
0
Revision 1.5 (07-18-06)
124
SMSC LAN9215
DATASHEET
SMSC [ SMSC CORPORATION ]
