AVR Freaks

Hello and thanks in advance for your consideration,

I'm writing a program that is intended to record data I'm capturing while performing an algorithm. I'd like to be able to maintain consistent write frequency between the different states of the high-level state machine but getting minor deviations in frequency.

Each state of course has a different number of instructions so I've created a timer in each state that I wait to expire before writing the data as the means to maintain the write frequency between states.

The simplified architecture is as follows:

State 1:

while(in state 1){

    // Gather data

    // Perform algorithm, if algorithm is completed this will exit the while loop in the state and return to the next state

    // Use timer to maintain consistent write frequency - actual timer code below

    while((TIFR & 0x04) == 0);            // wait here until timer expires (the timer was started before entering state 1)
    TCNT0 = 0x00;                              // Reset counter, starting timer again immediately
    TIFR |= (1<<OCF0B);                   // clear the flag

   // write data

}

State 2:

// In this state I just wait for a second timer (timer1) to expire before moving to the next state, all while continuing to record data

// Start timer1

while(Timer1_Expired == false){

    // gather data

    // wait for timer0 to expire to maintain consistent write frequency - actual timer code below

    while((TIFR & 0x04) == 0);            // wait here until timer expires
    TCNT0 = 0x00;                              // Reset counter, starting timer again immediately
    TIFR |= (1<<OCF0B);                   // clear the flag

    // write data

}

return state3;

State 3:

// In this state I perform a few unrelated actions and then stay in a loop until the end of available memory, continuing to sample and record data

while(Address < Max_Address){

    // gather data

    // wait for timer0 to expire in order to maintain consistent write frequency - actual timer code below

    while((TIFR & 0x04) == 0);            // wait here until timer expires
    TCNT0 = 0x00;                              // Reset counter, starting timer again immediately
    TIFR |= (1<<OCF0B);                   // clear the flag

    // write data

    Address++;

}

There is no variation in each state, but there is variation between states.

The frequency in state 1 is 48.31kHz

The frequency in state 2 is 47.95kHz

The frequency in state 3 is 48.48kHz

Any thoughts or guidance would be greatly appreciated.

Thanks!