First time in my life I'm using this DDS chip (AD9850) to create sine wave at a desired freq, where I upload the lookup table code and the desired freq. command via a with micro-controller. So my knowledge at the moment very limited.
The thing seems fine so far but the problem is at very low frequencies. At 1Hz and even 0.5Hz seems fine. But I also need down to 0.1Hz.
Here is the output of DDS when I send the number 0.1 to the DDS via the micro controller:
In my code I send the command from PC to micro as string and convert it to double. But for simplicity and to verify I use this code, and for 0.1Hz I set sendFrequency(0.1) in the loop.
But as you see the period is around 11.5 sec instead of 10 sec for 0.1Hz command.
I hope I could explain the issue well. Is there a way to calibrate or fine-tune this so that I would have more accurate result? Or I should live with the accuracy? Btw where in the data sheet one can refer to such relative uncertainty?