AHDL: Parameterized Counter (lpm_counter)
This example implements a parameterized counter that decodes two values.
You can change the width (LPM_WIDTH), direction (LPM_DIRECTION),
and modulus (LPM_MODULUS) parameters as needed for your design. The eq 11 port is used to decode when the counter reaches 11. AHDL operators are used to decode when the counter reaches 50 because only 16 eq ports are available in the lpm_counter function. After the counter
reaches 99, it will return to zero. This example uses an Include Statement (shown in blue text) to import the
contents of the Include File containing the Function Prototype for of the lpm_counter function.
An Instance Declaration (shown in red text) implements an instance of the function.
For more information on using this example in your project, go to:
upcnt99.tdf
INCLUDE "lpm_counter.inc";
SUBDESIGN upcnt99
(
clkena, cntena, clr, load, clk, data[7..0]
: INPUT;
eleven, fifty
: OUTPUT;
)
VARIABLE
-- Declare my_count as an 8-bit up counter with a
-- modulus of 100 (i.e., count to 99)
my_count : lpm_counter WITH (LPM_WIDTH = 8,
LPM_DIRECTION = "UP",
LPM_MODULUS = 100);
BEGIN
-- Connect the data, aclr, clock, clock enable, synchronous load,
-- and count enable ports. You must connect all ports that are used
-- to pins:
my_count.data[] = data[];
my_count.aclr = clr;
my_count.clock = clk;
my_count.clk_en = clkena;
my_count.cnt_en = cntena;
my_count.sload = load;
-- To indicate a 1 at the output (or decode) when the counter
-- reaches state 11, use the following:
eleven = my_count.eq11;
-- When the counter reaches 12, the output goes back to 0
-- Decode fifty.
IF (my_count.q[] == 50) THEN
fifty = VCC;
END IF;
END;
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