How to display the real frequency for an AD9850

[HenrikOlsson]

Hi,
Well, the basic answer is to take the tuning value and divide it by 2^32/125M or, in this case 17179869/(2^32/125000000) or, in short, 17179869/34.359738 = 500000.
Now, how to do this in PBP depends on if you're able to use LONG variables or not and to what accuracy you need the result. I don't know if you've seen my Wiki-article regarding the AD9850 or not but it describes two possible ways to calculate the tuning value when you know the frequency, it should be pretty straight forward to adapt any of the two methods to do the reverse.

/Henrik.

[kellyseye]

If you are using keyboard input for frequency selection just port the keypresses directly to the display at the same time you use it in the calculation for register coding.

[iw2fvo]

Kellyseye,

if I enter the output frequency then I have to compute the Tuning word.
If I enter the tuning word I have to compute the frequency to be displayed .
Tell me if I am wrong .
Thanks,
Ambrogio

[iw2fvo]

Thanks Henrik for having understood my problem.
I have seen all your implementations: they are great.
Congratulation.
I can use the LONG variables in PBP.
Thanks
Regards,
Ambrogio
IW2FVO