Scr firing angle control with avr

"You might be aware of basics of firing angle and its variation.So in a basic Firing angle variation mechanism you will need two things:
                                                           1)ZERO CROSSING DETECTION
                                                           2)FIRING SCR  AT DIFFERENT ANGLE
          First stage Zero crossing with AVR is damn easy thing as avr hardware supports zero-crossing detection. that means you can detect zero of 230 VAC with directly avr microcontroller and no additional hardware.
you can refer Avr's official application note to know more about zero crossing by microcontroller itself!!!! (Huh!!!!  QUESTION: How can avr tolerate 230 volts directly?
Answer: 1M resistor limits the current and internal avr diodes are used like clamper circuit.... to convert 230 volts to 5 volts that is accessible by micro-controller.)"

 

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