Bundles As (Kind Of) Entities

Defining the Bundle

bundle qspi is
  generic (
    CHIP_SELECTS : positive
  );

  port qmaster (
    mosi : out std_logic_vector(3 downto 0);
    miso : in  std_logic_vector(3 downto 0);
    sclk : out std_logic;
    cs   : out std_logic_vector(CHIP_SELECTS-1 downto 0)
  );
  port qslave (
    generic (
      SELECT : integer range 0 to CHIP_SELECTS-1
    );
    mosi : in  std_logic_vector(3 downto 0);
    miso : out std_logic_vector(3 downto 0);
    sclk : in  std_logic;
    cs   : in  std_logic
  );
  port sslave (
    generic (
      SELECT : integer range 0 to CHIP_SELECTS-1
    );
    mosi : in  std_logic;
    miso : out std_logic;
    sclk : in  std_logic;
    cs   : in  std_logic
  );
  signal mosi : std_logic_vector(3 downto 0);
  signal miso : std_logic_vector(3 downto 0);
  signal sclk : std_logic;
  signal cs   : std_logic_vector(CHIP_SELECTS-1 downto 0)
end bundle qspi;

bundle body qspi is
  port map qmaster (
    mosi => mosi,
    miso => miso,
    sclk => sclk,
    cs => cs
  );
  port map qslave (
    mosi => mosi,
    miso => miso,
    sclk => sclk,
    cs => cs(SELECT)
  );
  port map sslave (
    mosi => mosi(0),
    miso => miso(0),
    sclk => sclk,
    cs => cs(SELECT)
  );
end bundle body qspi;

Using the Bundle on an Entity

entity cpu is
  port (
    bundle spi : qspi.qmaster generic map (CHIP_SELECTS => 4);
    ...
  );
end entity cpu;

architecture Behavioral of cpu is
begin
  SPI_MASTER: process(clk, rst)
  begin
    if rst then
      spi.cs <= (others => '1');
      spi.sclk <= '0';
      spi.mosi <= (others => '0');
    elsif rising_edge(clk) then
      ...
  end process SPI_MASTER
end architecture Behavioral;

Using the Bundle at Top Level

architecture foo of bar is
  bundle qspi generic map (CHIP_SELECTS=>4);
begin

  CPU: entity work.cpu
    port map (
      spi => qspi.qmaster,
      ...blahblahblah...
    )

  FLASH : entity work.qspi_flash
    port map (
      spi => qspi.qslave generic map(SELECT=>0),
    );

  DAC : entity work.dac
    port map (
      spi => qspi.sslave generic map(SELECT => 1),
    );
end architecture foo;

-- Rob Gaddi - 2016-04-21

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