What does this AHDL code mean?

Hi,

I have some questions regarding the following piece of code...

In the AHDL code, the following variable is declared as below:

HDET_REG : DFF;

Its been used in the code as follows:

HDET_REG.CLK = DIGRESET;
HDET_REG.D = VCC;
HDET.REG.CLRN = !HDET;

My question is that....how does this DFF work

How does CLRN affect the output HDET_REG.Q

Any help is greatly appreciated.

Thank you,

Methi

methi

methi wrote:

> Hi,
>
> I have some questions regarding the following piece of code...
>
> In the AHDL code, the following variable is declared as below:
>
> HDET_REG : DFF;
>
> Its been used in the code as follows:
>
> HDET_REG.CLK = DIGRESET;
> HDET_REG.D = VCC;
> HDET.REG.CLRN = !HDET;

Probable typo :
HDET_REG.CLRN = !HDET;

Sounds like :

process (DigReset, Hdet)
begin
if Hdet ='1' then
HDET_Reg <= '0';
elsif rising_edge(DigReset) then
HDET_Reg <= '1';
end if;
end if;
end process;


Asynchronous rising edge detector.
Bad practice. Probably from a very small PLD, old design.

Bert Cuzeau

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