Altera Designing With Low-Level Primitives - Manual (Page 29)

Altera Corporation 2–7
April 2007 Designing with Low-Level Primitives User Guide
Primitive Reference
Table 2–3. ALT_OUTBUF_TRI Ports & 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 tristate output enable logic.
Output Ports
o Connect this port to a chip output pin or a wire to be connected to a chip output.
There must be no logic between the
o port and the chip output pin. If there is,
an error results.
Parameters
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 The location is 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.
slow_slew_rate A logic option that implements slow low-to-high or high-to-low transitions on
output pins to help reduce switching noise. Current legal values are “
on ” and
“ off .”
This assignment is ignored by the Fitter for Stratix II and Cyclone II devices.
This parameter is not supported for Stratix II GX or HardCopy II devices.
slew_rate The slow_slew_rate parameter is not available for Stratix III and
Cyclone III. These two families support the slew_rate parameter instead.
Accepts any positive integer value including 0. Default value is –1, which is
equivalent to not using this parameter. Available only for Stratix III and
Cyclone III.