n_bit_demux

Hi,
I try this:

>entity demultiplex is
> generic(N :integer := 4);
> port(X :in bit;
> Sel :integer range 0 to N-1;
> Y ut bit_vector(N-1 downto 0));
>end demultiplex;
>
>architecture dataflow of demultiplex is
>begin
> Y <= (Sel => X, others => '0');
>end dataflow;

but it does an error:

Y <= (Sel => X, others => '0');
|
non-locally static or null range choice must be only choice

Gietek

> but it does an error:
>
> Y <= (Sel => X, others => '0');
> |
> non-locally static or null range choice must be only choice

This will work

process
begin
Y <= (others=>'0');
Y(sel) <= X;
end process;

Egbert Molenkamp

Egbert Molenkamp

Gietek a écrit:
> Hi,
> I try this:
>
> >entity demultiplex is
> > generic(N :integer := 4);
> > port(X :in bit;
> > Sel :integer range 0 to N-1;
> > Y ut bit_vector(N-1 downto 0));
> >end demultiplex;
> >
> >architecture dataflow of demultiplex is
> >begin
> > Y <= (Sel => X, others => '0');
> >end dataflow;
>
> but it does an error:
>
> Y <= (Sel => X, others => '0');
> |
> non-locally static or null range choice must be only choice

I suggested not so long ago but I hadn't tested it. It seems this is not
allowed. Use a process instead:

process (X, Sel)
begin
Y <= (others => '0');
Y(Sel) <= X;
end process;

(this works, I used it many times)

Nicolas

Nicolas Matringe

Gietek <> wrote in message news:<>...
> Hi,
> I try this:
>
> >entity demultiplex is
> > generic(N :integer := 4);
> > port(X :in bit;
> > Sel :integer range 0 to N-1;
> > Y ut bit_vector(N-1 downto 0));
> >end demultiplex;
> >
> >architecture dataflow of demultiplex is
> >begin
> > Y <= (Sel => X, others => '0');
> >end dataflow;
>
> but it does an error:
>
> Y <= (Sel => X, others => '0');
> |
> non-locally static or null range choice must be only choice

Gietek, try this:

architecture dataflow of demultiplex is
begin
p : process( sel )
begin
for i in 0 to N - 1 loop
if i = sel then
Y( i ) <= X;
else
Y( i ) <= '0';
end if;
end loop;
end process;
end;

Charles

Charles M. Elias

Egbert Molenkamp wrote:

>
> This will work

Not quite! The sensitivity list is missing.

> process
process(x, sel)
> begin
> Y <= (others=>'0');
> Y(sel) <= X;
> end process;

Paul.

Paul Uiterlinden

>
> Gietek, try this:
>
> architecture dataflow of demultiplex is
> begin
> p : process( sel )
> begin
> for i in 0 to N - 1 loop
> if i = sel then
> Y( i ) <= X;
> else
> Y( i ) <= '0';
> end if;
> end loop;
> end process;
> end;


Thank, this works. I mean compilation and simulation was successful on
Altera Max2plus. But here I work on Cadence and SimVision doesn't
simulate it. Bits and bit_vectors waveforms are unknown - "???"

>
> Charles

Gietek