Primitive: I/O Pulldown
- PRIMITIVE_GROUP: I/O
- PRIMITIVE_SUBGROUP: WEAK_DRIVER
Introduction
The design element is a weak pulldown element that pulls an undriven I/O to a logic zero state. For example, if the I/O is 3-stated and not driven by any other element, a logic 0 will exist on the I/O.
Port Descriptions
| Port | Direction | Width | Function |
|---|---|---|---|
| O | Output | 1 | Pulldown output. Connect directly to a top-level port in the design. |
Design Entry Method
| Instantiation | Yes |
| Inference | Yes, via property |
| IP and IP Integrator Catalog | No |
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;
-- PULLDOWN: I/O Pulldown
-- Spartan UltraScale+
-- Xilinx HDL Language Template, version 2025.2
PULLDOWN_inst : PULLDOWN
port map (
O => O -- 1-bit output: Pulldown output (connect directly to top-level port)
);
-- End of PULLDOWN_inst instantiation
Verilog Instantiation Template
// PULLDOWN: I/O Pulldown
// Spartan UltraScale+
// Xilinx HDL Language Template, version 2025.2
PULLDOWN PULLDOWN_inst (
.O(O) // 1-bit output: Pulldown output (connect directly to top-level port)
);
// End of PULLDOWN_inst instantiation
Related Information
- Spartan UltraScale+ FPGAs SelectIO Resources User Guide (UG861)