Intel® Quartus® Prime Standard Edition User Guide: Platform Designer

ID 683364
Date 12/15/2018
Public
Document Table of Contents

4.11.4. Almost-Full and Almost-Empty Thresholds to Prevent Overflow and Underflow

You can use almost-full and almost-empty thresholds as a mechanism to prevent FIFO overflow and underflow. This feature is available only in the single-clock FIFO core. To use the thresholds, turn on the Use fill level, Use almost-full status, and Use almost-empty status parameters. You can access the almost_full_threshold and almost_empty_threshold registers via the csr interface and set the registers to an optimal value for your application.

You can obtain the almost-full and almost-empty statuses from almost_full and almost_empty interfaces ( Avalon® -ST status source). The core asserts the almost_full signal when the fill level is equal to or higher than the almost-full threshold. Likewise, the core asserts the almost_empty signal when the fill level is equal to or lower than the almost-empty threshold.