void setup() {
  pinMode(A0, INPUT);
  pinMode(3, OUTPUT);
}

void loop() {
  int input = analogRead(A0);
  analogWrite(3, map(input, 0, 1023, 0, 255));
}


sketch.ino

diagram.json

// Wokwi Custom Chip - For information and examples see:
// https://docs.wokwi.com/chips-api/getting-started
//
// SPDX-License-Identifier: MIT
// Copyright (C) 2022 Uri Shaked / wokwi.com

#include "wokwi-api.h"
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define MILLIS 1000 /* micros */

typedef struct {
  pin_t pin_in;
  timer_t timer;
  uint64_t last_low;
  uint64_t last_high;
  float duty;
  uint32_t frequency;
  bool ignore_next;
} chip_state_t;

void chip_pin_change(void *user_data, pin_t pin, uint32_t value) {
  chip_state_t *chip = user_data;

  uint64_t nanos = get_sim_nanos();
  if (value) {
    uint64_t delta = nanos - chip->last_high;
    uint64_t high_time = chip->last_low - chip->last_high;
    if (delta && !chip->ignore_next) {
      uint32_t frequency = 1000000000 / delta;
      if (frequency != chip->frequency) {
        printf("Frequency: %d\n", frequency);
        chip->frequency = frequency;
      }
    }
    float duty = high_time ? (float)high_time / (float)delta : 0;
    if (fabs(duty - chip->duty) > 0.0001 && !chip->ignore_next) {
      printf("Duty: %.2f\n", duty);
      chip->duty = duty;
    }
    chip->last_high = nanos;
    chip->ignore_next = false;
  } else {
    chip->last_low = nanos;
  }
  timer_start(chip->timer, 100 * MILLIS, false); // Minimum frequency: 10 Hz
}

static void timer_callback(void *user_data) {
  chip_state_t *chip = user_data;
  // If this timer fired, it means we haven't seen any change in the pin in a while. 
  // Consider this a stable state.
  float duty = pin_read(chip->pin_in) ? 1.0 : 0.0;
  if (fabs(duty - chip->duty) > 0.0001) {
    printf("Duty: %.2f\n", duty);
    chip->duty = duty;
  }
  chip->frequency = 0;
  chip->ignore_next = true;
}


void chip_init() {
  chip_state_t *chip = malloc(sizeof(chip_state_t));

  chip->pin_in = pin_init("IN", INPUT);
  chip->last_low = 0;
  chip->last_high = 0;
  chip->frequency = 0;
  chip->duty = 0;
  chip->ignore_next = true;

  const timer_config_t timer_config = {
    .user_data = chip,
    .callback = timer_callback,
  };
  chip->timer = timer_init(&timer_config);

  const pin_watch_config_t watch_config = {
    .edge = BOTH,
    .pin_change = chip_pin_change,
    .user_data = chip,
  };
  pin_watch(chip->pin_in, &watch_config);

  // The following message will appear in the browser's DevTools console:
  printf("PWM Analyzer running!\n");
}
