I/O Structure
Stratix devices have an I/O interconnect similar to the R4 and C4
interconnect to drive high-fanout signals to and from the I/O blocks.
There are 16 signals that drive into the I/O blocks composed of four
output enables io_boe[3..0], four clock enables io_bce[3..0], four
clocks io_bclk[3..0], and four clear signals io_bclr[3..0]. The
pin’s datainsignals can drive the IO interconnect, which in turn drives
the logic array or other I/O blocks. In addition, the control and data
signals can be driven from the logic array, providing a slower but more
flexible routing resource. The row or column IOE clocks, io_clk[7..0],
provide a dedicated routing resource for low-skew, high-speed clocks.
I/O clocks are generated from regional, global, or fast regional clocks (see
“PLLs & Clock Networks” on page 2–73). Figure 2–62 illustrates the
signal paths through the I/O block.
Figure 2–62. Signal Path through the I/O Block
Row or Column
io_clk[7..0]
io_boe[3..0]
To Other
IOEs
io_bce[3..0]
From I/O
Interconnect
io_bclk[3..0]
io_bclr[3..0]
io_datain0
To Logic
Array
io_datain1
oe
ce_in
ce_out
io_coe
io_cce_in
io_cce_out
Control
Signal
Selection
IOE
aclr/apreset
sclr/spreset
clk_in
From Logic
Array
io_cclr
io_cclk
clk_out
io_dataout0
io_dataout1
2–108
Stratix Device Handbook, Volume 1
Altera Corporation
July 2005
ALTERA [ ALTERA CORPORATION ]
