demystifying use of table pointer in

Posted on Feb 6, 2014

Sinusoidal pulse width modulation (SPWM). I`ve discussed about how to generate the sine table, how to implement it, how to practically generate the SPWM signals (with example code) and also how to implement feedback with simple sine table manipulation with table pointer instead of complex PID control. All these methods have one thing in common regarding the implementation - use of the sine table and

demystifying use of table pointer in
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its control with the table pointer. Whether you use or implement feedback or not, the table pointer is used to access and retrieve values from the sine table. It took quite a while for me to understand exactly how the table pointer works in this case to retrieve data from the sine table and feed it to the PWM module and generate the required output 50Hz frequency (you can use any frequency but my requirement is 50Hz). I had come across the method and its explanation when coding for the dsPIC33 microcontroller while I was attempting to make a sine wave inverter using the dsPIC33. After a lot of research and thinking, I could finally implement it for PIC16. While many have seen my posted codes and explanations regarding sinusoidal pulse width modulation (SPWM), some people have requested me to explain how the table pointer in the interrupt works. Remembering my difficult experience with this, I decided to write up this article to help all of you who are struggling with this to help clear your doubts and make you understand exactly how it works so that one can implement SPWM with a sine table with any number of table values and for any desired output frequency. Let`s take a look at the code line by line. And I`ll explain it all. Keep in mind that the target microcontroller is a PIC16F684 running off an oscillator frequency of 16MHz. So, if you`re attempting to port  the code to any other microcontroller keep in mind that the...

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