Issues porting capacitive touch code from Arduino to avr

Using Arduino Programming Questions
1

I'm trying to port GreatScott's capacitive touch code to avr. From my understanding the timer is constantly generating a pulse via the TIMER1_COMPA interrupt and the circuit works when I test it through Arduino IDE but I've hit a roadblock. When trying to port the code the circuit doesn't work at all and if it does work it's very unreliable. I've managed to pinpoint the issue being in the ISR(TIMER1_COMPA_vect) method. Here's the main body code which is pretty much identical in both implementations

unsigned long value;
uint8_t outputstate = 0;

void setup()
{
    Serial.begin(9600);
    TCCR1A = 0;
    TCCR1B = (1 << ICES1) | (1 << WGM12) | (1 << CS10);

    OCR1A = 8000;
    TIMSK1 = (1 << OCIE1A);
    ACSR = (1 << ACI) | (1 << ACIE) | (1 << ACIS1) | (1 << ACIS0);

    DDRB |= (1 << DDB4);
}

void loop()
{
    if (value > 1000)
        outputstate = -1;
    else
        outputstate = 0;

    if (outputstate)
        PORTB |= (1 << DDB4);
    else
        PORTB &= ~(1 << DDB4);

    Serial.println(value);
    _delay_ms(100);
}

ISR(ANALOG_COMP_vect)
{
    value = TCNT1;
}

The only real differences exist in the following method.

//arduino
ISR(TIMER1_COMPA_vect)
{
    pinMode(8, OUTPUT);
    digitalWrite(8, HIGH);
    pinMode(8, INPUT);
}

//avr
ISR(TIMER1_COMPA_vect)
{
    cli();
    DDRB |= 1;
    
    PORTB |= 1;
    
    DDRB &= ~1;
    PORTB &= ~1;
    sei();
}

Now, I cannot figure out for the life of me why my implementation gives me a different result than the arduino code. Any help would be appreciated. Website

2

Which Arduino did GreatScott use ?

3

Because the time take between driving pin 8 high and making it an input is very different perhaps? digitalWrite and pinMode have overheads of several microseconds each, whereas the time between

    PORTB |= 1;

and

    DDRB &= ~1;

is a small fraction of a µs as there is almost no overhead, just direct register bit flips. Thus the pulse on the pin lasts a tiny fraction of the time compared to the Arduino code. An explicit delay is needed to define the pulse width.

4

Note: In the 'avr' version, cli() and sei() are NOT needed in an ISR.

5

aren't most Arduinos AVRs ?
What specific AVR are you using. (and what are you porting from, but someone asked already.)

6

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