Altera Designing With Low-Level Primitives - Manual (Page 26)

2–4 Altera Corporation
Designing with Low-Level Primitives User Guide April 2007
Primitives
Table 2–2. ALT_OUTBUF Ports & Parameters
Port/Parameter Description/Value
Input Ports
i
Connect this port to the logic in the design that generates the output signal.
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.
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.
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. The default value is –1, which
is equivalent to not using this parameter.
This parameter is available only for Stratix III and Cyclone III.