How i can generate clean square waves?

I am using sqr() function to generate square waves with DAC38J84. The problem that I am facing right now is that the sample points pattern in the created excel sheet is not constant. For example, I see 8 points (High) then 7 points (low) then 9 point (high) and so on. That variability cause some jitters on the output.

Is there any way that I can make sure that the square wave pattern is constant? and how sqr(0 function can handle the situation where is the number of samples per cycle is odd or float?

Best regards. Thank you so much.