Intel® Quartus® Prime Pro Edition User Guide: Design Compilation

ID 683236
Date 3/28/2022

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Document Table of Contents
Give Feedback Initial Constructs and Memory System Tasks

The Intel® Quartus® Prime software infers power-up conditions from the Verilog HDL initial constructs. The Intel® Quartus® Prime software also creates power-up settings for variables, including RAM blocks. If the Intel® Quartus® Prime software encounters non-synthesizable constructs in an initial block, it generates an error.

To avoid such errors, enclose non-synthesizable constructs (such as those intended only for simulation) in translate_off and translate_on synthesis directives. Synthesis of initial constructs enables the power-up state of the synthesized design to match the power-up state of the original HDL code in simulation.

Note: Initial blocks do not infer power-up conditions in some third-party EDA synthesis tools. If you convert between synthesis tools, you must set your power-up conditions correctly.

Intel® Quartus® Prime synthesis supports the $readmemb and $readmemh system tasks to initialize memories.

Verilog HDL Code: Initializing RAM with the readmemb Command

reg [7:0] ram[0:15];
$readmemb("ram.txt", ram);

When creating a text file to use for memory initialization, specify the address using the format @<location > on a new line, and then specify the memory word such as 110101 or abcde on the next line.

The following example shows a portion of a Memory Initialization File (.mif) for the RAM.

Text File Format: Initializing RAM with the readmemb Command