56
AT94KAL Series FPSLIC
Rev. 1138G–FPSLI–11/03
Figure 33.
Out Instruction – AVR Writing to the FPGA
Note:
1. AVR expects Write to be captured by the FPGA upon posedge of the AVR clock.
Figure 34.
In Instruction – AVR Reading FPGA
Notes:
1. AVR captures read data upon posedge of the AVR clock.
2. At the end of an FPGA read cycle, there is a chance for the AVR data bus contention
between the FPGA and another peripheral to start to drive (active IORE at new address ver-
sus FP Select “n”), but since the AVR clock would have already captured the data
from AVR DBUS (= FPGA Data Out), this is a “don’t care” situation.
AVR INST
AVR CLOCK
AVR IOWE
AVR IOADR
(FISUA, B, C or D)
AVR DBUS
(FPGA DATA IN)
FPGA IOWE
FPGA I/O
SELECT "n"
FPGA CLOCK
(SET TO AVR
SYSTEM CLOCK)
WRITE DATA VALID
(1)
OUT INSTRUCTION
AVR INST
AVR CLOCK
AVR IORE
AVR IOADR
(FISUA, B, C or D)
AVR DBUS
(FPGA DATA OUT)
FPGA IORE
FPGA I/O
SELECT "n"
READ DATA VALID
(1)
IN INSTRUCTION
(2)
(2)