Intel® Quartus® Prime Standard Edition User Guide: Design Constraints

ID 683492
Date 1/10/2019
Public
Document Table of Contents

2.4.3.3. Overriding Default I/O Pin Analysis

You can override the default I/O analysis of pins to accommodate I/O rule exceptions, such as for analyzing VREF or inactive pins.

Each device contains VREF pins, each supporting one or more I/O pins. A VREF pin and its I/O pins comprise a VREF bank. The VREF pins are typically assigned inputs with VREF I/O standards, such as HSTL- and SSTL-type I/O standards. Conversely, VREF outputs do not require the VREF pin. When a voltage-referenced input is present in a VREF bank, only a certain number of outputs can be present in that VREF bank. I/O assignment analysis treats bidirectional signals controlled by different output enables as independent output enables.

To assign the Output Enable Group option to bidirectional signals to analyze the signals as a single output enable group, follow these steps:

  1. To access this assignment in the Pin Planner, right-click the All pins list and click Customize Columns.
  2. Under Available columns, add Output Enable Group to Show these columns in this order. The column appears in the All Pins list.
  3. Enter the same integer value for the Output Enable Group assignment for all sets of signals that are driving in the same direction.

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