Altera Designing With Low-Level Primitives - Manual (Page 31)

Altera Corporation 2–9
April 2007 Designing with Low-Level Primitives User Guide
Primitive Reference
Table 2–4. ALT_IOBUF Ports and Parameters
Port/Parameter Description/Value
Input Ports
i
Connect this port to the logic in the design that generates the output signal.
oe Connect this port to the tri-state output enable logic.
Output Ports
o Connect this port to the logic in the design that receives the input signal
Bidirectional Port
Connect this port to the chip bidir pin or an entity bidir port. There must
be no logic between the
io
port and the chip bidir pin. If there is, an error
results.
Parameter
io_standard A logic option that specifies the I/O standard of a pin. Different device families
support different I/O standards, and restrictions apply to placing pins with
different I/O standards together.
current_strength A logic option that sets the drive strength of a pin. Specific numerical strength
settings are appropriate only for pins with certain I/O standards. You can
specify any legal current strength value here (including “minimum current” or
“maximum current”). The parameter name
current_strength_new is also
supported for backward compatibility.
location Any legal pin location for the current device.
enable_bus_hold An option to enable bus-hold circuitry. Legal values are “ on ” and “ off .”
weak_pull_up_resistor An option to enable the weak pull-up resistor. Legal values are “ on ” and “ off .”
termination Any legal on-chip-termination value for the current device. For GX families, this
parameter supports only regular termination, and not GXB termination.
This parameter is supported for Stratix III, Stratix II, Stratix II GX, HardCopy II,
Cyclone III, and Cyclone II.
To set separate input and output values, use input_termination and
output_termination parameters instead. This parameter can not be
used along with input_termination or output_termination .
This parameter sets both input termination value and output termination values
for Stratix III and Cyclone III devices. However, note that the Fitter ignores any
input termination parameters for Cyclone III devices.
To set separate input and output values, use input_termination and
output_termination parameters instead. This parameter can not be
used with input_termination or output_termination .
input_termination Any legal input on-chip termination value for the current device. This parameter
cannot be used with the
termination parameter. This parameter is
supported in Stratix III devices only.