VHDL AXI FIFO using block RAM

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This VHDL implementation of an AXI-style FIFO has generic data width and depth settings.

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Description

The axi_fifo.vhd module uses the ready/valid handshake to control the writing and reading. The FIFO synthesizes into block RAM and is compatible with the AXI/AMBA bus architecture standard.

The receiver controls the ready signal while the sender controls the valid signal. Data transfer only happens when ready and valid are ‘1’ within the same clock cycle. Thus, the AXI interface has built-in flow control.

The capacity of the FIFO is equal to ram_depth minus one. One slot is always kept empty to distinguish between a full and an empty FIFO.

You don’t need to enable read/write memory address collision checks in the synthesis tool because the FIFO never reads from and writes to the same slot simultaneously.

Entity

entity axi_fifo is
  generic (
    ram_width : natural;
    ram_depth : natural
  );
  port (
    clk : in std_logic;
    rst : in std_logic;
 
    -- AXI input interface
    in_ready : out std_logic;
    in_valid : in std_logic;
    in_data : in std_logic_vector(ram_width - 1 downto 0);
 
    -- AXI output interface
    out_ready : in std_logic;
    out_valid : out std_logic;
    out_data : out std_logic_vector(ram_width - 1 downto 0)
  );
end axi_fifo;

Main article

Click here to read more about how I created this module:
How to make an AXI FIFO in block RAM using the ready/valid handshake

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How does it work?

Tested on Windows and Linux Loading Gif.. How it works

License agreement

MIT License

Copyright (c) 2024 Jonas Julian Jensen

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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