Using Atmega TCNT1 - atmega

Question

I'm trying to use an arduino uno to show some students how to make their own 'auto tune' however the code that I wrote is not outputting any signal. The goal is to sample values into an array at one rate and output the data from the array(FIFO)at a slower rate. My understanding is that TCNT1 increments each clock tick, I'm using 16 MHz in my case, and that I can base if logic on the value of TCNT1, I use a mod function here to take and store a single adc value and then play that value to the dac at a later time. acdT dacT represent my timing logic. I've built an external DAC to read only 8 (of 10) bit values from d0-d7 (PORTD). Why am I not seeing a signal?
int i = 0;
int j = 0;
int adcT = 328; // 329 clock tics
int dacT = 349; // 350 clock tics
int buff[15]; // 16 length buffer to store adc values
void setup ()
{
PRR &= ~(1<<PRADC); //ADC turned on
ADMUX = 0x60; //AVcc, left adjusted, ADC0 pin
ADCSRA = 0xC0;//ADC Enabled, no auto trigger
DDRD=0xFF; // set portd to d0 thru d7 digital pins
DDRC=0x00; // accept input from any analog input
TCCR1B |= 1<<CS10; // sets the clock to the system clock ie no pre scaler
}
void loop ()
{
if((TCNT1%acdT == 0) || TCNT1 == 0) // execute at 0 and mod329 clock tics
{
ADCSRA|=(1<<ADSC); // take one adc reading
while(!(ADCSRA & (1<<ADIF))); // wait until the reading is complete
ADCSRA|=(1<<ADIF); //reset adc for next command
buff[i] = ADCH; // take the adc value into the array
i++ // increment
}
if((TCNT1%dacT == 0)) %% TCNT1 ~= 0// execute at mod350 clock tics
{
PORTD = buff[j]; // send the adc reading to digital output
j++;
}
if(TCNT1 == 5262 ) // LCM/3 of 329(16samples) and 350(15samples)
{
TCNT1 = 0;// reset ticker
i = 0;
j = 0;
}
if(TCNT1 == 336)
{
PORTD = buff[15]; // play 16th adc sample to clear array
}
}

Answer 1

TCCR1B |= 1<<CS10; // sets the clock to the system clock ie no pre scaler
And there's your problem. You're attempting to find the modulus of a counter that runs faster than your code. Use the output capture and other features of the timer to trigger interrupts and reset the timer at the appropriate times instead of trying to catch a passing bullet with your bare hands.