Hi,
I have problem in generating sine wave with specific frequency. I am using ATmega32-A micro controller and AD9833 programmable waveform generator. I am able to generate sine wave with 125 KHz.

 

Your routine

void SetWGFreq(unsigned int freq)

passes in freq which has units of kilohertz, thus you cannot use it to define anything with a finer unit.

So when you pass in freq treat it as hertz, not kiloherts. That could be as simple as changing one line:

freg2 = (unsigned long)freq*33.554432;   //Number based on a MCLK of 8 MHz 
                                         // AND freq in Hz

but also check the size of your variables to insure you can fit your range.

I'm also unsure of the precision of the multiplication in this statement: just when does it convert the floating point number to an integer: before or after the multiplication. That cast may force an incorrect answer. I would single step this code to see just what that line is doing.

 

It occurred to me that by eliminating the floating point arithmetic several complications drop away:

freg2 = (freq * 33554432) / 1000000;   //Number based on a MCLK of 8 MHz 
                                       // AND freq in Hz

One could also add 500000 to the product (before division) to compute a rounded result.

Just insure the variables can handle the range. It is pretty big.

 

It occurred to me that by eliminating the floating point arithmetic several complications drop away:

freg2 = (freq * 33554432) / 1000000;   //Number based on a MCLK of 8 MHz 
                                       // AND freq in Hz

One could also add 500000 to the product (before division) to compute a rounded result.

Just insure the variables can handle the range. It is pretty big.

I have small doubt i am using unsigned int for freq variable variable. If i want to set 125.3 Khz then what will happen, i think it exceeds the limit.

125300*33554432=4190725159600/1000000

'
I will try by declaring as float then i will check what will happen and i will inform you.

 

Hello,

Perhaps this application note might help:
AN-1070: Programming the AD9833/AD9834

Bertus