# sinusoidal wave & VHDL

Discussion in 'VHDL' started by tiflis, Jan 16, 2007.

1. ### tiflisGuest

Good afternoon
someone knows to suggest me how I can generate a sinusoidal wave with
frequency = 1HZ in vhdl?
I have already generated a wave quadrant
How could I pass to the sinusoidal wave?

tiflis, Jan 16, 2007

2. ### Jim LewisGuest

tiflis wrote:
> Good afternoon
> someone knows to suggest me how I can generate a sinusoidal wave with
> frequency = 1HZ in vhdl?
> I have already generated a wave quadrant
> How could I pass to the sinusoidal wave?
>

For a testbench modeling, there are trig functions in
the package ieee.math_real. They expect angles in radians.
Trig functions in math_real:
Name [arguments] return Description
sin [real] real sine in radians
cos [real] real cosine in radians

There are also handy constants:
MATH_PI pi 3.14159265358979323846
MATH_2_PI 2*pi 6.28318530717958647693

There are more than this, but these are what I used.

Cheers,
Jim

Jim Lewis, Jan 16, 2007

3. ### tiflisGuest

Jim Lewis ha scritto:

> tiflis wrote:
> > Good afternoon
> > someone knows to suggest me how I can generate a sinusoidal wave with
> > frequency = 1HZ in vhdl?
> > I have already generated a wave quadrant
> > How could I pass to the sinusoidal wave?
> >

> For a testbench modeling, there are trig functions in
> the package ieee.math_real. They expect angles in radians.
> Trig functions in math_real:
> Name [arguments] return Description
> sin [real] real sine in radians
> cos [real] real cosine in radians
>
> There are also handy constants:
> MATH_PI pi 3.14159265358979323846
> MATH_2_PI 2*pi 6.28318530717958647693
>
> There are more than this, but these are what I used.
>
> Cheers,
> Jim

ok thanks.
Meantime I have found this in Internet:

http://www.doulos.com/knowhow/vhdl_designers_guide/models/sine_wave_generator/

It could it are useful to me?

tiflis, Jan 17, 2007
4. ### Frank BussGuest

tiflis wrote:

> ok thanks.
> Meantime I have found this in Internet:
>
> http://www.doulos.com/knowhow/vhdl_designers_guide/models/sine_wave_generator/
>
> It could it are useful to me?

Yes, this could be useful for you. But you have to think about the output:
If you feed 1 Hz to a DAC (e.g. a R2R network) and your lookup table is
small, then you need a filter at the output, which depends on the size of
the lookup table and your quality requirement for the output signal.

--
Frank Buss,
http://www.frank-buss.de, http://www.it4-systems.de

Frank Buss, Jan 17, 2007

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