[SOLVED] Understaning the code of following

[thannara123]

I am learning the sinewave generation a great member Thahamid posted a blog in edabord as follwos

Demystifying The Use of Table Pointer in SPWM - Application in Sine Wave Inverter

I have previously written quite a few articles on sinusoidal pulse width modulation (SPWM). I've discussed about how to generate the sine t...

tahmidmc.blogspot.com

i didnt understand the working of following code anybody help me ?

TBL_POINTER_SHIFT = TBL_POINTER_NEW >> 11;
DUTY_CYCLE = TBL_POINTER_SHIFT;

what are the values of TBL_POINTER_SHIFT variable
it gets 1 when the TBL_POINTER_SHIFT become 2048 ,with lower the value it will be zero
am curiuos how the technique behind it ?

 

[FvM]

The variable names are somehow contra-intuitive.

It's basically a DDS generator. What they call TABLE_POINTER_xx is usually designated DDS accumulator. The upper 5 bits are used as index into the sine table.

 

[thannara123]

I didnt get well please may i get more details of working ?

 

[FvM]

Numerically-controlled oscillator - Wikipedia

en.m.wikipedia.org

 

[thannara123]

I understood the working of code by reaptly reading .thanks