Primitive: I/O Pullup
- PRIMITIVE_GROUP: I/O
- PRIMITIVE_SUBGROUP: WEAK_DRIVER
Introduction
The design element is a weak pullup element that pulls an undriven I/O to a logic one state. For example, if the I/O is 3-stated and not driven by any other element, a logic 1 will exist on the I/O.
Port Descriptions
| Port | Direction | Width | Function |
|---|---|---|---|
| O | Output | 1 | Pullup 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;
-- PULLUP: I/O Buffer Weak Pull-up
-- 7 Series
-- Xilinx HDL Language Template, version 2026.1
PULLUP_inst : PULLUP
port map (
O => O -- Pullup output (connect directly to top-level port)
);
-- End of PULLUP_inst instantiation
Verilog Instantiation Template
// PULLUP: I/O Buffer Weak Pull-up
// 7 Series
// Xilinx HDL Language Template, version 2026.1
PULLUP PULLUP_inst (
.O(O) // Pullup output (connect directly to top-level port)
);
// End of PULLUP_inst instantiation
Related Information
- 7 Series FPGAs SelectIO Resources User Guide (UG471)