The following is a summary of the parameters and usage of the lpm_rom module:

VHDL Port and Generic Defenition:

COMPONENT lpm_rom
   GENERIC (LPM_WIDTH: POSITIVE;
      LPM_TYPE: STRING := L_ROM;
      LPM_WIDTHAD: POSITIVE;
      LPM_NUMWORDS: STRING := UNUSED;
      LPM_FILE: STRING;
      LPM_ADDRESS_CONTROL: STRING := REGISTERED;
      LPM_OUTDATA: STRING := REGISTERED);
   PORT (address: IN STD_LOGIC_VECTOR(LPM_WIDTHAD-1 DOWNTO 0);
      inclock: IN STD_LOGIC := '1';
      outclock: IN STD_LOGIC := '1';
      memenab: IN STD_LOGIC := '1';
      q: OUT STD_LOGIC_VECTOR(LPM_WIDTH-1 DOWNTO 0));

END COMPONENT;

LPM_WIDTH (required)

Width of data[] and q[] ports.

LPM_WIDTHAD (required)

Width of the address port.

LPM_NUMWORDS

Size of memory in "words". The default (ie. when not specified) is 2^LPM_WIDTHAD.

LPM_FILE

Name of the Memory Initialization File (.mif) or Hexadecimal (Intel-Format) File (.hex) containing the values in the ROM.

LPM_ADDRESS_CONTROL

"REGISTERED" or "UNREGISTERED". "REGISTERED" means the address must be latched in by the rising edge of inclock. "UNREGISTERD" means the address on the port is used directly in the read operation. The default is "REGISTERED".

LPM_OUTDATA

"REGISTERED" or "UNREGISTERED". Specifies whether the output data must be latched by a rising edge on outclock before it appears at the output data (q) port (registered), or immediately appears on the q port (unregistered). The default is "REGISTERED".

address[] (required)

Address port (LPM_WIDTHAD bits wide).

inclock (optional but recommended)

For use in synchronous operation, a rising edge on inclock latches in the signal on the address port.

outclock (optional but recommended)

For use in synchronous operation, a rising edge on outclock latches the read value onto the data (q) port.

memenab

Used for tri-state functionality of the q port. A high signal allows the read data to appear on the q port. A low value makes the q port high impedance.

q[] (required)

Data output (LPM_WIDTH bits wide).

Typical Operation