植物栽培LEDをPWM制御で節電、成長促進（？）

#if !defined(ESP8266)
#error This code is designed to run on ESP8266 and ESP8266-based boards! Please check your Tools->Board setting.
#endif

// These define's must be placed at the beginning before #include "ESP8266_PWM.h"
// _PWM_LOGLEVEL_ from 0 to 4
// Don't define _PWM_LOGLEVEL_ > 0. Only for special ISR debugging only. Can hang the system.
#define _PWM_LOGLEVEL_ 4

#define USING_MICROS_RESOLUTION true // false

// Default is true, uncomment to false
// #define CHANGING_PWM_END_OF_CYCLE     false

// Select a Timer Clock
#define USING_TIM_DIV1 true    // for shortest and most accurate timer
#define USING_TIM_DIV16 false  // for medium time and medium accurate timer
#define USING_TIM_DIV256 false // for longest timer but least accurate. Default

// To be included only in main(), .ino with setup() to avoid `Multiple Definitions` Linker Error
#include "ESP8266_PWM.h"

#ifndef LED_BUILTIN
#define LED_BUILTIN 2
#endif

#define HW_TIMER_INTERVAL_US 20L

volatile uint32_t startMicros = 0;

// Init ESP8266Timer
ESP8266Timer ITimer;

// Init ESP8266_ISR_PWM
ESP8266_PWM ISR_PWM;

void IRAM_ATTR TimerHandler()
{
  ISR_PWM.run();
}

#define PIN_D4 2  // Pin D4 mapped to pin GPIO2/TXD1 of ESP8266

// 周波数モードOFF
// #define USING_PWM_FREQUENCY true

// You can assign pins here. Be carefull to select good pin to use or crash
// uint32_t PWM_Pin    = LED_BUILTIN;
uint32_t PWM_Pin = PIN_D4;

// You can assign any interval for any timer here, in Hz
float PWM_Freq1 = 1.0f;
// You can assign any interval for any timer here, in Hz
float PWM_Freq2 = 1.0f;

// You can assign any interval for any timer here, in microseconds
uint32_t PWM_Period1 = 100000 / PWM_Freq1;
// You can assign any interval for any timer here, in microseconds
uint32_t PWM_Period2 = 400 / PWM_Freq2;

// You can assign any duty_cycle for any PWM here, from 0-100
float PWM_DutyCycle1 = 50.0;
// You can assign any duty_cycle for any PWM here, from 0-100
float PWM_DutyCycle2 = 50.0;

// Channel number used to identify associated channel
int channelNum;

////////////////////////////////////////////////

void setup()
{
  // Serial.begin(115200);
  Serial.begin(74880);

  while (!Serial)
    ;

  delay(2000);

  Serial.print(F("\nStarting ISR_Changing_PWM on "));
  Serial.println(ARDUINO_BOARD);
  Serial.println(ESP8266_PWM_VERSION);
  Serial.print(F("CPU Frequency = "));
  Serial.print(F_CPU / 1000000);
  Serial.println(F(" MHz"));

  // Interval in microsecs
  if (ITimer.attachInterruptInterval(HW_TIMER_INTERVAL_US, TimerHandler))
  {
    startMicros = micros();
    Serial.print(F("Starting ITimer OK, micros() = "));
    Serial.println(startMicros);
  }
  else
    Serial.println(F("Can't set ITimer. Select another freq. or timer"));

  // Just to demonstrate, don't use too many ISR Timers if not absolutely necessary
  // You can use up to 16 timer for each ISR_PWM
  // void setPWM(uint32_t pin, float frequency, float dutycycle
  // , timer_callback_p StartCallback = nullptr, timer_callback_p StopCallback = nullptr)
}

void loop()
{
  Serial.print(F("Using PWM Freq = "));
  Serial.print(PWM_Freq1);
  Serial.print(F(", PWM DutyCycle = "));
  Serial.println(PWM_DutyCycle1);

#if USING_PWM_FREQUENCY
  // You can use this with PWM_Freq in Hz
  channelNum = ISR_PWM.setPWM(PWM_Pin, PWM_Freq1, PWM_DutyCycle1);
#else
#if USING_MICROS_RESOLUTION
  // Or using period in microsecs resolution
  channelNum = ISR_PWM.setPWM_Period(PWM_Pin, PWM_Period1, PWM_DutyCycle1);
#else
  // Or using period in millisecs resolution
  channelNum = ISR_PWM.setPWM_Period(PWM_Pin, PWM_Period1 / 1000, PWM_DutyCycle1);
#endif
#endif

  // delay(10000);
  delay(3000);

  ISR_PWM.deleteChannel((unsigned)channelNum);

  Serial.print(F("Using PWM Freq = "));
  Serial.print(PWM_Freq2);
  Serial.print(F(", PWM DutyCycle = "));
  Serial.println(PWM_DutyCycle2);

#if USING_PWM_FREQUENCY
  // You can use this with PWM_Freq in Hz
  channelNum = ISR_PWM.setPWM(PWM_Pin, PWM_Freq2, PWM_DutyCycle2);
#else
#if USING_MICROS_RESOLUTION
  // Or using period in microsecs resolution
  channelNum = ISR_PWM.setPWM_Period(PWM_Pin, PWM_Period2, PWM_DutyCycle2);
#else
  // Or using period in millisecs resolution
  channelNum = ISR_PWM.setPWM_Period(PWM_Pin, PWM_Period2 / 1000, PWM_DutyCycle2);
#endif
#endif

  // delay(10000);
  delay(3000);

  ISR_PWM.deleteChannel((unsigned)channelNum);
}