Sie wave from PWM using PIC16f877A

[emanuelpic]

pwm + pic16f877a

Hi everybody, am doing an inverter based on PIC 16f877A. I want to feed the analog inputs RA0 with carrier sawtooth 2000hz and input RA1 with variable sine ve om etween 2 to 70 hz so that I can compare and generate the PWM accordingly anfrptd fed to H- bridge. my question is how I can get variable sinewave from 2 to 70 hz CCP1 PWM. thanx your help

 

[Tahmid]

pwm using pic16f877a

Hi,
Instead of trying complex sine wave inverter, why you not try to make a simple sq wave one? First orient with the tidbits of PIc 16F877A and then go for complex coding. Only help will not suffice. Thanka.

 

[emanuelpic]

inverter based on pic 16f877a

Thanx for reply but please how to make simple sinewave with variable frequency between 20hz to 70 hz and frequency change should follow a variable dc voltage change

 

[harii74]

pic16f877a dac

In what application you are doing for?
For electrical load you can try for quasi sine wave,
other wise go for DAC along with Microcontroller.But you need voltage amplifier in output of DAC.

 

[elrayes]

sine wave using pwm and lpf

I'm with the idea of using a DAC, just make equation and output its value on a port then the DAC will convert it to sine.
or take the equation output to PWM but you will need LPF with the PWM output, maybe a smoothing capacitor is enough.
or generate square wave using PIC and connect the output to a 2nd order LPF and you will get a sine wave.

good luck