/*
Using void setup() and void loop():
Sketch uses 460 bytes (5%) of program storage space. Maximum is 8192 bytes.
Global variables use 9 bytes (1%) of dynamic memory, leaving 503 bytes for local variables. Maximum is 512 bytes.

Using int main(void) and while() loop:
Sketch uses 140 bytes (1%) of program storage space. Maximum is 8192 bytes.
Global variables use 0 bytes (0%) of dynamic memory, leaving 512 bytes for local variables. Maximum is 512 bytes.

_delay_ms():
Error if used like this: _delay_ms(delay_time):
The _delay_ms() function in <util/delay.h> only works when the delay time is known at compile time,

*/


#define F_CPU 8000000UL // 8 MHz internal oscillator
#include <avr/io.h>
#include <util/delay.h>
#include <TinyDebug.h>


// Pin Definitions
#define POT_PIN  PB2  // ADC1
#define LED_PIN  PB1

void adc_init(void) { 
  // ADMUX – ADC Multiplexer Selection Register
  // Set the ADC reference to Vcc (5V) and select ADC1 (PB2) as input
  // Table 17-3. Voltage Reference Selections for ADC
  // REFS2:X REFS1:0 REFS0:0 VCC used as Voltage Reference, disconnected from PB0 (AREF).
  // (REFS bits default to Vcc in ATtiny85, so we don’t set them explicitly)
  ADMUX = (1 << MUX0); // MUX0 = 1 selects ADC1 (PB2)

  // ADCSRA – ADC Control and Status Register A
  // Enable the ADC, set prescaler to 64 for 125 kHz ADC clock (8,000,000 / 64 = 125,000)
  // Ideal ADC clock range is 50–200 kHz for good resolution
  ADCSRA = (1 << ADEN)  // Bit 7 – ADEN: ADC Enable
           | (1 << ADPS2) | (1 << ADPS1); // Prescaler = 64

  // DIDR0 – Digital Input Disable Register 0
  // Disable digital input buffer on ADC1 (PB2) to reduce power/noise
  // Strongly recommended for better ADC readings
  DIDR0 = (1 << ADC1D);
}

uint16_t adc_read(void) {
  // Bit 6 – ADSC: ADC Start Conversion
  // In Single Conversion mode, write this bit to one to start each conversion.
  ADCSRA |= (1 << ADSC);           // Start conversion
  while (ADCSRA & (1 << ADSC));    // Wait for conversion to finish
  return ADC;                      // Return combined ADCL/ADCH value (10-bit), ADCL (low byte) and ADCH (high byte)
}

/*
// ===== Using void setup(), and void loop() =====
void setup() {
  Debug.begin();
  DDRB |= (1 << LED_PIN); // Set LED pin as output
  adc_init();
}

void loop() {
  uint16_t value = adc_read(); // Read analog value (0–1023)

  // Map value of ADC to a delay range: 0 -> 1ms to 1023 -> 511ms
  uint16_t delay_time = (value / 2) + 1; // Prevent 0 ms delay
  Debug.print("delay_time:"); Debug.println(delay_time);

  PORTB |= (1 << LED_PIN); // Turn LED on
  delay(delay_time);
    
  PORTB &= ~(1 << LED_PIN); // Turn LED off
  delay(delay_time);
}
// ===== Using void setup(), and void loop() =====
*/

//*
// ===== Using int main(void), and while (1) loop =====
int main(void) {
  Debug.begin();

  DDRB |= (1 << LED_PIN); // Set LED pin as output
  adc_init();             // Initialize the ADC

  while(1) {
    uint16_t value = adc_read(); // Read analog value (0–1023)

    // Map value of ADC to a delay range: 0 -> 1ms to 1023 -> 511ms
    uint16_t delay_time = (value / 2) + 1; // Prevent 0 ms delay
    Debug.print("delay_time:"); Debug.println(delay_time);

    // _delay_ms() throws an error message unless used in a for loop.
    // Seet ChatGPT for detains
    PORTB |= (1 << LED_PIN); // Turn LED on
    for (uint16_t i = 0; i < delay_time; i++) {
      _delay_ms(1);
    }
    PORTB &= ~(1 << LED_PIN); // Turn LED off
    for (uint16_t i = 0; i < delay_time; i++) {
      _delay_ms(1);
    }

  return 0;
}
// ===== Using int main(void), and while (1) loop =====
//*/