Hello,

I just got an ADAU1701 Mini Evaluation Board. I am using SigmaStudio 3.1.

For my programm, working at 192kHz item sample rate, I need to generate both a cosine and a sine at 40kHz.

I have two main problems :

First, there is no cosine generation function. I somehow managed to create a cosine by using sin(2*a)=2*sin(a)*cos(a), but it uses up 2 sine, and there's a wrong point when sin(x)=0 (cos(x) should be 1, it is 0).

Another problem, concerning the sine functiun, is that, even if the sample rate is set over 48kHZ, it will work at 48kHz maximum. So at 192kHz, the frequency is divided by 4...

Any suggestions?

On another note, is there a way to use the output of a function (the sine generation function for example) two times (ie. linking it to two other functiuns) ?

Thanks for your help,

Regards,

Matthias.

The sine tone generators in SigmaStudio support frequencies up to fs/2. Check this FAQ to ensure that you're properly setting up your hardware for higher sampling rates: http://ez.analog.com/docs/DOC-1431

A cosine is simply a sine shifted by 90 degrees. You can shift the output of your sine wave with a delay block, which has 1-sample resolution, but this may not be good enough for your application. This resolution cannot create a 2nd signal that is exactly 90 degrees out of phase with the first. With fs=192 kHz, your sampling period is about 5.21 us. A quarter wave length (90 degrees, or pi/2) of a 40 kHz signal has a period of 6.25 us. So, you can see that method will give either a phase shift that's less than 90 degrees (1 sample) or more than 90 degrees (2 samples). Of course, this simple delay solution will work better for signals at lower frequencies.

You can use a t-connection cell (in the Schematic Design library in the toolbox) to send the output of a single block to the inputs of multiple blocks.