Changing timer 2's OCR2A's value during runtime.

I have a timer setup as follows:

    /******** Set timer1 for 8-bit fast PWM output ********/
  pinMode(9, OUTPUT);       // Make timer's PWM pin an output
  TCCR1B  = (1 << CS10);    // Set prescaler to full 16MHz
  TCCR1A |= (1 << COM1A1);  // PWM pin to go low when TCNT1=OCR1A
  TCCR1A |= (1 << WGM10);   // Put timer into 8-bit fast PWM mode
  TCCR1B |= (1 << WGM12);  

  /******** Set up timer 2 to call ISR ********/
  TCCR2A = 0;               // We need no options in control register A
  TCCR2B = (1 << CS21);     // Set prescaller to divide by 8
  TIMSK2 = (1 << OCIE2A);   // Set timer to call ISR when TCNT2 = OCRA2
  OCR2A = 28; // sets the frequency of the generated wave 32 is C3

I'd like to change the value of OCR2A during runtime. Simply changing the value in a function doesn't do what I was expecting. Does the timer have to be reset first or interrupts disabled then re-enabled? Thanks for any help that can be offered.

The processor data sheet, timer section, describes in detail how and when to change OCR registers. Study it carefully.

For help on the forum, explain what you tried, what you expected to happen and what happened instead.