abut arduino

Are you trying to generate pulses of controlled width, one per half cycle of an incoming sine wave ?

If so then please tell us the frequency of the input sine wave, the range of pulse widths you need coming out, where the sine wave comes from and what hardware you have. Some diagrams would be nice. With some additional information it will be possible to help you. If my guess at what you are trying to do is correct it is possible in principle.

MK

Yes just measure both positive and negative values during entire cycle.

Hi

you could measure the time between two "zero crossings". That's the period of the PWM signal. During the negative part of the sine waveform, use a timer to drive PWM output

Cheers

Ambrogio

How about offset the sine wave to 50% of VRef (Capacitor coupled will do it, and a divider network), then simply read the whole waveform as a positive value

this way 0V = 511 decimal from ADC, -2.5V will be 0 decimal and +2.5V will be 1023

this assumes the input sine wave is appropriatly scaled to a +-2.5V max signal

All the questions Mike asked are still valid though, please provide

You also have not said what resolution you desire to read the values, I am assuming 10 bit based on the built in ADC of the arduino and with my proposed solution, you will have 9 bits in each direction (Simple assume the MSB is a sign bit

Peter Oakes & Michael Kellett

are correct asking for more information as stated.. Also oversample twice the frequency you plan for better accuracy is highly recommended.

Clem

do you have a problem with using a full-wave rectifier as that sounds like your best bet?

#include<PWM.h>

int32_t frequency =100000;

void setup()

{

InitTimersSafe() ;

bool success = SetPinFrequencySafe(9, frequency);

if(success) {

  pinMode(13, OUTPUT);

  digitalWrite(13,HIGH);

}

}

void loop() {

int sensorValue= analogRead(A0);

pwmWrite(9, sensorValue /4);

delay(30);

}

                                                                                          from the signal generator i have  provide a supply of  5 v pp and 50 hz frequency, +ve part provided to the  diode and the diode is connected to the  a0 pin in the arduino uno  and-ve part of signal generator to ground the .then is have taken output from 9 pin and at this point i am getting pwm of  only +ve cycle of sine wave input as reference(as i have used a diode)

now i need to generate pwm of -ve cycle

1. i want arduino code to store the +ve cycle pwm wave  in other pin and then during -ve cycle i want to output it through this pin .by this i would get  pwm for both +ve and -ve cycle of sine wave  and  it would be helpful if any way is there to distinguish the pwm for +ve and -ve cycle

2 in a simple way i need to generate a pwm for -ve cycle and need to do it by arduino code only and not by rectifier (less circuit part  and more part must be done in coding)

any way u could help me to do this it would be of great help.

We need to send same values of PWM to negative cycle. If we measure negative supply, output will be zero as diode blocks negative supply. We need to send psuedo values to negative cycle.

can u tell me the code for that

now we just thought its better to use codes than more diodes ,just much simpler way of codes of arduino