LAN9311 Datasheet, PDF (109/461 Pages) SMSC Corporation – Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface

8.5.6
Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface
Datasheet
RX Data FIFO Direct PIO Reads
In this mode only A[2:1] are decoded, and any 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 read and the FIFO_SEL and END_SEL signals have the same timing
characteristics as the address lines. An RX Data FIFO direct 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 Table 15.10, “RX Data FIFO Direct PIO Read Cycle Timing Values,” on page 450.
The cycle ends when either or both nCS and nRD are de-asserted. These signals may be asserted
and de-asserted in any order. Read data is valid as indicated in the functional timing diagram in
Figure 8.5.
Note: Address lines A[2:1] are still used, and address lines A[9:3] are ignored.
Please refer to Section 15.5.6, "RX Data FIFO Direct PIO Read Cycle Timing," on page 450 for the
AC timing specifications for RX Data FIFO direct PIO read operations.
FIFO_SEL
END_SEL
VALID
A[x:3]
A[2:1]
VALID
nCS, nRD
D[15:0] (OUTPUT)
(READ DATA FROM RX DATA FIFO)
VALID
Figure 8.5 Functional Timing for RX Data FIFO Direct PIO Read Operation
SMSC LAN9311/LAN9311i
109
DATASHEET
Revision 2.0 (02-14-13)