54
AT94KAL Series FPSLIC
Rev. 1138G–FPSLI–11/03
(FPGAIOWE
←
IOWE). FPGA macros utilizing one or more FPGA I/O select lines must use
the FPGA I/O read/write enables, FPGAIORE or FPGAIOWE, to qualify each select line. The
FIADR bit will be cleared (zero) during AVR reset.
• Bits 6..2 - Res: Reserved Bits
These bits are reserved and always read as zero.
• Bits 1, 0 - XFIS1, 0: Extended FPGA I/O Select Bits 1, 0
XFIS[1:0] determines which one of the four FPGA I/O select lines will be set (one) within the
accessed group. An I/O read or write to one of the four dual-purpose I/O addresses, FISUA..D,
will access one of four groups. Table 13 details the FPGA I/O selection scheme.
Note:
1. Not available on AT94K05.
In summary, 16 select signals are sent to the FPGA for I/O addressing. These signals are
decoded from four base I/O Register addresses (FISUA..D) and extended to 16 with two bits
from the FPGA I/O Select Control Register, XFIS1 and XFIS0. The FPGA I/O read and write
signals, FPGAIORE and FPGAIOWE, are qualified versions of the AVR IORE and IOWE sig-
nals. Each will only be active if one of the four base I/O addresses is accessed.
Reset: all select lines become active and an FPGAIOWE strobe is enabled. This is to allow the
FPGA design to load zeros (8’h00) from the D-bus into appropriate registers.
Table 13.
FPGA I/O Select Line Scheme
Read or Write
I/O Address
FISCR Register
FPGA I/O Select Lines
XFIS1
XFIS0
15..12
11..8
7..4
3..0
FISUA $14 ($34)
0
0
0000
0000
0000
0001
0
1
0000
0000
0000
0010
1
0
0000
0000
0000
0100
1
1
0000
0000
0000
1000
FISUB $15 ($35)
0
0
0000
0000
0001
0000
0
1
0000
0000
0010
0000
1
0
0000
0000
0100
0000
1
1
0000
0000
1000
0000
FISUC $16 ($36)
0
0
0000
0001
0000
0000
0
1
0000
0010
0000
0000
1
0
0000
0100
0000
0000
1
1
0000
1000
0000
0000
FISUD $17 ($37)
0
0
0001
0000
0000
0000
0
1
0010
0000
0000
0000
1
0
0100
0000
0000
0000
1
1
1000
0000
0000
0000