Xilinx CPLD Libraries Guide

About Design Elements
Attribute Type Allowed Values Default Description
IOSTANDARD String Consult the product Data
Sheet.
"DEFAULT" Specifies the I/O standard to be
used for this output.
SLEW String "SLOW" or "FAST” "SLOW” Specifies the slew rate of
the output driver. Consult
the product Data Sheet for
recommendations of the best
setting for this attribute.
VHDL Instantiation Template
Unless they already exist, copy the following two statements and paste them before the entity declaration.
Library UNISIM;
use UNISIM.vcomponents.all;
-- OBUF: Single-ended Output Buffer
-- All devices
-- Xilinx HDL Libraries Guide, version 10.1.1
OBUF_inst : OBUF
generic map (
DRIVE => 12,
IOSTANDARD => "DEFAULT",
SLEW => "SLOW")
port map (
O => O, -- Buffer output (connect directly to top-level port)
I => I -- Buffer input
);
-- End of OBUF_inst instantiation
Verilog Instantiation Template
// OBUF: Single-ended Output Buffer
// All devices
// Xilinx HDL Libraries Guide, version 10.1.1
OBUF #(
.DRIVE(12), // Specify the output drive strength
.IOSTANDARD("DEFAULT"), // Specify the output I/O standard
.SLEW("SLOW") // Specify the output slew rate
) OBUF_inst (
.O(O), // Buffer output (connect directly to top-level port)
.I(I) // Buffer input
);
// End of OBUF_inst instantiation
For More Information
• See the appropriate CPLD User Guide.
• See the appropriate CPLD Data Sheets.
CPLD Libraries Guide
ISE 10.1 www.xilinx.com 495