Potentiometer Oscillator rev_04

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    - Project: Potentiometer Oscillator
    - Source Code NOT compiled for: ESP32 DevKit V1
    - Source Code created on: 2025-10-20 22:32:12

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/****** SYSTEM REQUIREMENTS *****/
/****** SYSTEM REQUIREMENT 1 *****/
    /* create a pulse generator of one millisecond */
    /* duration with a variable frequency of 10Hz to */
    /* 100Hz , adjustable via the potentiometer */
/****** END SYSTEM REQUIREMENTS *****/


/* START CODE */

/****** DEFINITION OF LIBRARIES *****/

/****** FUNCTION PROTOTYPES *****/
void setup(void);
void loop(void);

/***** DEFINITION OF ANALOG INPUT PINS *****/
const uint8_t frequency_adjust_Potentiometer_Vout_PIN_D4 = D4;

// Pulse output pin
const uint8_t pulse_output_PIN = 25; // Output pulse

void setup(void)
{
    // put your setup code here, to run once:

    pinMode(frequency_adjust_Potentiometer_Vout_PIN_D4, INPUT);
    pinMode(pulse_output_PIN, OUTPUT);
    digitalWrite(pulse_output_PIN, LOW);

    // Optional: initialize ADC characteristics if supported
    // (commented out to preserve compatibility across boards)
    // analogReadResolution(12);
}


void loop(void)
{
    // put your main code here, to run repeatedly:

    // Read potentiometer and map to frequency range [10,100] Hz
    int potValue = analogRead(frequency_adjust_Potentiometer_Vout_PIN_D4);
    const int MIN_FREQ = 10;
    const int MAX_FREQ = 100;
    int freqHz = map(potValue, 0, 4095, MIN_FREQ, MAX_FREQ);
    if (freqHz < MIN_FREQ) freqHz = MIN_FREQ;
    if (freqHz > MAX_FREQ) freqHz = MAX_FREQ;

    // Period in microseconds for the selected frequency
    static int currentFreqHz = -1;
    static unsigned long period_us = 0;
    static unsigned long lastChangeTime = 0;
    static bool pulseHigh = false;

    // Sync frequency state on first run or when changed
    if (currentFreqHz != freqHz) {
        currentFreqHz = freqHz;
        period_us = 1000000UL / (unsigned long)freqHz; // total period
        // Reset timing to align with new frequency
        lastChangeTime = micros();
        // Start with a HIGH pulse
        digitalWrite(pulse_output_PIN, HIGH);
        pulseHigh = true;
        return;
    }

    const unsigned long PULSE_WIDTH_US = 1000; // 1 ms HIGH pulse

    unsigned long now = micros();

    if (pulseHigh) {
        // Keep high for 1 ms
        if (now - lastChangeTime >= PULSE_WIDTH_US) {
            digitalWrite(pulse_output_PIN, LOW);
            lastChangeTime = now;
            pulseHigh = false;
        }
    } else {
        // Low phase: rest of the period
        unsigned long lowDuration = period_us > PULSE_WIDTH_US ? (period_us - PULSE_WIDTH_US) : 0;
        if (lowDuration > 0 && (now - lastChangeTime >= lowDuration)) {
            digitalWrite(pulse_output_PIN, HIGH);
            lastChangeTime = now;
            pulseHigh = true;
        }
    }
}

/* END CODE */