MAX 7000 Programmable Logic Device Family Data Sheet
Programmable Interconnect Array
Logic is routed between LABs via the programmable interconnect array
(PIA). This global bus is a programmable path that connects any signal
source to any destination on the device. All MAX 7000 dedicated inputs,
I/O pins, and macrocell outputs feed the PIA, which makes the signals
available throughout the entire device. Only the signals required by each
LAB are actually routed from the PIA into the LAB. Figure 7 shows how
the PIA signals are routed into the LAB. An EEPROM cell controls one
input to a 2-input ANDgate, which selects a PIA signal to drive into the
LAB.
Figure 7. PIA Routing
To LAB
PIA Signals
While the routing delays of channel-based routing schemes in masked or
FPGAs are cumulative, variable, and path-dependent, the MAX 7000 PIA
has a fixed delay. The PIA thus eliminates skew between signals and
makes timing performance easy to predict.
I/O Control Blocks
The I/O control block allows each I/O pin to be individually configured
for input, output, or bidirectional operation. All I/O pins have a tri-state
buffer that is individually controlled by one of the global output enable
signals or directly connected to ground or VCC. Figure 8 shows the I/O
control block for the MAX 7000 family. The I/O control block of EPM7032,
EPM7064, and EPM7096 devices has two global output enable signals that
are driven by two dedicated active-low output enable pins (OE1and OE2).
The I/O control block of MAX 7000E and MAX 7000S devices has six
global output enable signals that are driven by the true or complement of
two output enable signals, a subset of the I/O pins, or a subset of the I/O
macrocells.
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Altera Corporation
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