PWM generation using Arduino uno

In a comment to Dmitry Grigoryev’s answer you wrote:

void setup()
{
    TCCR2A = 0x23;
    TCCR2B = 0x09;
    OCR2A = 159;
    pinMode(3, OUTPUT);
}

void loop()
{
    OCR2B = 80;
}

It seems you already have the solution to your problem: that's exactly the way to do it!

Well, there is a catch: since you are using OCR2A to define the period of your timer, this means you are left with a single PWM channel, where the duty cycle is controlled by OCR2B. Given that the Arduino Uno has only three timers, it would seem you can only have up to three PWM channels at 100 kHz.

But there is a solution. Timer 1 has a feature the other timers don't have: you can define its period using using the input capture register ICR1 instead of OCR1A. This leaves you both output compare registers available for PWM. For this you have to set the timer into waveform generation mode 14, i.e. fast PWM with TOP = ICR1. Now you can have your four channels, with Timer 0 driving pin 5, Timer 2 driving pin 3, and Timer 1 driving pins 9 and 10.

Some caveats:

• As already pointed out by Dmitry Grigoryev, your PWM resolution is slightly reduced.

• By reconfiguring Timer 0, you loose the Arduino Timekeeping function millis(), micros() and, delay(). You could write your own ISR to count the overflows of some other timer, but it would be called every 10 µs: even if it is very short it would eat a non-trivial fraction of your CPU power.

use analogwrite() that's the arduino interface to the chips internal PWM capabalities.

1. Use AnalogWrite.

2. Use PWM or output compare feature of the various timers.

3. Use an internal PWM generator.

...

edit: here is an example of how approach 1) above can be done.

two 100Khz pulse trains at 10% dc and 50% dc, independently configurable. zero overhead and all within the confines of arduino.