v1.0.0 for ATmega using MightyCore

### Initial Releases v1.0.0

1. Initial coding for AVR **ATmega164(A/P), ATmega324(A/P/PA/PB), ATmega644(A/P), ATmega1284(P)** using [MightyCore](https://github.com/MCUdude/MightyCore)
2. The hybrid ISR-based PWM channels can generate from very low (much less than 1Hz) to highest PWM frequencies up to 500Hz with acceptable accuracy.

CONTRIBUTING.md

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+## Contributing to ATmega_Slow_PWM
+
+### Reporting Bugs
+
+Please report bugs in ATmega_Slow_PWM if you find them.
+
+However, before reporting a bug please check through the following:
+
+* [Existing Open Issues](https://github.com/khoih-prog/ATmega_Slow_PWM/issues) - someone might have already encountered this.
+
+If you don't find anything, please [open a new issue](https://github.com/khoih-prog/ATmega_Slow_PWM/issues/new).
+
+---
+
+### How to submit a bug report
+
+Please ensure to specify the following:
+
+* Arduino IDE version (e.g. 1.8.19) or Platform.io version
+* `Arduino MightyCore` Core Version (e.g. Arduino MightyCore Core v2.1.3)
+* Board type (e.g. ATmega164, ATmega324, ATmega644, ATmega1284, etc.)
+* Contextual information (e.g. what you were trying to achieve)
+* Simplest possible steps to reproduce
+* Anything that might be relevant in your opinion, such as:
+  * Operating system (Windows, Ubuntu, etc.) and the output of `uname -a`
+  * Network configuration
+
+---
+
+### Example
+
+```
+Arduino IDE version: 1.8.19
+Arduino MightyCore Core v2.1.3
+ATmega1284 with Optiboot
+OS: Ubuntu 20.04 LTS
+Linux xy-Inspiron-3593 5.15.0-46-generic #49~20.04.1-Ubuntu SMP Thu Aug 4 19:15:44 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
+
+Context:
+I encountered a crash while trying to use the Timer Interrupt.
+
+Steps to reproduce:
+1. ...
+2. ...
+3. ...
+4. ...
+```
+
+---
+
+### Sending Feature Requests
+
+Feel free to post feature requests. It's helpful if you can explain exactly why the feature would be useful.
+
+There are usually some outstanding feature requests in the [existing issues list](https://github.com/khoih-prog/ATmega_Slow_PWM/issues?q=is%3Aopen+is%3Aissue+label%3Aenhancement), feel free to add comments to them.
+
+### Sending Pull Requests
+
+Pull Requests with changes and fixes are also welcome!
+

LICENSE

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+MIT License
+
+Copyright (c) 2022 Khoi Hoang
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

changelog.md

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+# AVR_Slow_PWM Library
+
+[![arduino-library-badge](https://www.ardu-badge.com/badge/AVR_Slow_PWM.svg?)](https://www.ardu-badge.com/AVR_Slow_PWM)
+[![GitHub release](https://img.shields.io/github/release/khoih-prog/AVR_Slow_PWM.svg)](https://github.com/khoih-prog/AVR_Slow_PWM/releases)
+[![GitHub](https://img.shields.io/github/license/mashape/apistatus.svg)](https://github.com/khoih-prog/AVR_Slow_PWM/blob/master/LICENSE)
+[![contributions welcome](https://img.shields.io/badge/contributions-welcome-brightgreen.svg?style=flat)](#Contributing)
+[![GitHub issues](https://img.shields.io/github/issues/khoih-prog/AVR_Slow_PWM.svg)](http://github.com/khoih-prog/AVR_Slow_PWM/issues)
+
+---
+---
+
+## Table of Contents
+
+* [Changelog](#changelog)
+  * [Initial Releases v1.0.0](#Initial-Releases-v100)
+
+---
+---
+
+## Changelog
+
+
+### Initial Releases v1.0.0
+
+1. Initial coding for AVR **ATmega164(A/P), ATmega324(A/P/PA/PB), ATmega644(A/P), ATmega1284(P)** using [MightyCore](https://github.com/MCUdude/MightyCore)
+2. The hybrid ISR-based PWM channels can generate from very low (much less than 1Hz) to highest PWM frequencies up to 500Hz with acceptable accuracy.
+
+

examples/ISR_8_PWMs_Array/ISR_8_PWMs_Array.ino

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+/****************************************************************************************************************************
+  ISR_8_PWMs_Array.ino
+  For AVR ATmega164, ATmega324, ATmega644, ATmega1284 with MightyCore
+  Written by Khoi Hoang
+
+  Built by Khoi Hoang https://github.com/khoih-prog/ATmega_Slow_PWM
+  Licensed under MIT license
+
+  Now with we can use these new 16 ISR-based PWM channels, while consuming only 1 hwarware Timer.
+  Their independently-selected, maximum interval is practically unlimited (limited only by unsigned long miliseconds)
+  The accuracy is nearly perfect compared to software timers. The most important feature is they're ISR-based timers
+  Therefore, their executions are not blocked by bad-behaving functions / tasks.
+  This important feature is absolutely necessary for mission-critical tasks.
+*****************************************************************************************************************************/
+
+// Select just 1 TIMER to be true
+#define USE_TIMER_1     true
+#define USE_TIMER_2     false
+// TIMER_3 Only valid for ATmega1284 and ATmega324PB (not ready in core yet)
+#define USE_TIMER_3     false
+// TIMER_4 Only valid for ATmega324PB, not ready in core yet
+#define USE_TIMER_4     false
+
+// These define's must be placed at the beginning before #include "ATmega_Slow_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_      3
+
+#if (_PWM_LOGLEVEL_ > 3)
+  #if USE_TIMER_1
+    #warning Using Timer1
+  #elif USE_TIMER_3
+    #warning Using Timer3
+  #endif
+#endif
+
+#define USING_MICROS_RESOLUTION       true    //false
+
+// Default is true, uncomment to false
+//#define CHANGING_PWM_END_OF_CYCLE     false
+
+// To be included only in main(), .ino with setup() to avoid `Multiple Definitions` Linker Error
+#include "ATmega_Slow_PWM.h"
+
+#include <SimpleTimer.h>              // https://github.com/jfturcot/SimpleTimer
+
+#define LED_OFF             HIGH
+#define LED_ON              LOW
+
+#ifndef LED_BUILTIN
+  #define LED_BUILTIN       13
+#endif
+
+#ifndef LED_BLUE
+  #define LED_BLUE          10
+#endif
+
+#ifndef LED_RED
+  #define LED_RED           11
+#endif
+
+#define USING_HW_TIMER_INTERVAL_MS        true
+
+// Don't change these numbers to make higher Timer freq. System can hang
+#define HW_TIMER_INTERVAL_MS        0.1f
+#define HW_TIMER_INTERVAL_FREQ      10000L
+
+volatile uint32_t startMicros = 0;
+
+// Init ATmega_Slow_PWM, each can service 16 different ISR-based PWM channels
+ATmega_Slow_PWM ISR_PWM;
+
+//////////////////////////////////////////////////////
+
+void TimerHandler()
+{ 
+  ISR_PWM.run();
+}
+
+//////////////////////////////////////////////////////
+
+#define PIN_D0      0
+#define PIN_D1      1
+#define PIN_D2      2
+#define PIN_D3      3
+#define PIN_D4      4
+#define PIN_D5      5
+#define PIN_D6      6
+
+//////////////////////////////////////////////////////
+
+// You can assign pins here. Be careful to select good pin to use or crash, e.g pin 6-11
+uint32_t PWM_Pin[] =
+{
+  LED_BUILTIN, PIN_D0, PIN_D1,  PIN_D2,  PIN_D3,  PIN_D4,  PIN_D5,  PIN_D6
+};
+
+#define NUMBER_ISR_PWMS         ( sizeof(PWM_Pin) / sizeof(uint32_t) )
+
+// You can assign any interval for any timer here, in Hz
+float PWM_Freq[] =
+{
+  1.0f,  2.0f,  3.0f,  4.0f,  5.0f,  6.0f,  7.0f,  8.0f,
+};
+
+// You can assign any interval for any timer here, in Microseconds
+float PWM_DutyCycle[] =
+{
+  5.0, 10.0, 20.0, 25.0, 30.0, 35.0, 40.0, 45.0
+};
+
+typedef void (*irqCallback)  ();
+
+
+// In Portenta_H7, avoid doing something fancy in ISR, for example complex Serial.print with String() argument
+// The pure simple Serial.prints here are just for demonstration and testing. Must be eliminate in working environment
+// Or you can get this run-time error / crash
+void doingSomething0()
+{
+}
+
+void doingSomething1()
+{
+}
+
+void doingSomething2()
+{
+}
+
+void doingSomething3()
+{
+}
+
+void doingSomething4()
+{
+}
+
+void doingSomething5()
+{
+}
+
+void doingSomething6()
+{
+}
+
+void doingSomething7()
+{
+}
+
+
+irqCallback irqCallbackStartFunc[] =
+{
+  doingSomething0,  doingSomething1,  doingSomething2,  doingSomething3, 
+  doingSomething4,  doingSomething5,  doingSomething6,  doingSomething7
+};
+
+////////////////////////////////////////////////
+
+void setup()
+{ 
+  Serial.begin(115200);
+  while (!Serial && millis() < 5000);
+
+  delay(2000);
+
+  Serial.print(F("\nStarting ISR_8_PWMs_Array on ")); Serial.println(BOARD_NAME);
+  Serial.println(ATMEGA_SLOW_PWM_VERSION);
+  Serial.print(F("CPU Frequency = ")); Serial.print(F_CPU / 1000000); Serial.println(F(" MHz"));
+
+  // Timer0 is used for micros(), millis(), delay(), etc and can't be used
+  // Select Timer 1-2 for UNO, 1-5 for MEGA, 1,3,4 for 16u4/32u4
+  // Timer 2 is 8-bit timer, only for higher frequency
+  // Timer 4 of 16u4 and 32u4 is 8/10-bit timer, only for higher frequency
+
+#if USING_HW_TIMER_INTERVAL_MS
+
+/////////////////////////////////////////
+
+#if USE_TIMER_1
+
+  ITimer1.init();
+
+  // Using ATmega324 with 16MHz CPU clock ,
+  // For 16-bit timer 1, set frequency from 0.2385 to some KHz
+  // For 8-bit timer 2 (prescaler up to 1024, set frequency from 61.5Hz to some KHz
+
+  if (ITimer1.attachInterruptInterval(HW_TIMER_INTERVAL_MS, TimerHandler))
+  {
+    Serial.print(F("Starting  ITimer1 OK, micros() = ")); Serial.println(micros());
+  }
+  else
+    Serial.println(F("Can't set ITimer1. Select another freq. or timer"));
+
+#elif USE_TIMER_2
+
+  ITimer2.init();
+
+  if (ITimer2.attachInterruptInterval(HW_TIMER_INTERVAL_MS, TimerHandler))
+  {
+    Serial.print(F("Starting  ITimer2 OK, micros() = ")); Serial.println(micros());
+  }
+  else
+    Serial.println(F("Can't set ITimer2. Select another freq. or timer"));
+
+#elif USE_TIMER_3
+
+  ITimer3.init();
+
+  if (ITimer3.attachInterruptInterval(HW_TIMER_INTERVAL_MS, TimerHandler))
+  {
+    Serial.print(F("Starting  ITimer3 OK, micros() = ")); Serial.println(micros());
+  }
+  else
+    Serial.println(F("Can't set ITimer3. Select another freq. or timer"));
+
+#endif
+
+/////////////////////////////////////////
+
+#else
+
+/////////////////////////////////////////
+
+#if USE_TIMER_1
+
+  ITimer1.init();
+
+  // Using ATmega324 with 16MHz CPU clock ,
+  // For 16-bit timer 1, set frequency from 0.2385 to some KHz
+  // For 8-bit timer 2 (prescaler up to 1024, set frequency from 61.5Hz to some KHz
+
+  if (ITimer1.attachInterrupt(HW_TIMER_INTERVAL_FREQ, TimerHandler))
+  {
+    Serial.print(F("Starting  ITimer1 OK, micros() = ")); Serial.println(micros());
+  }
+  else
+    Serial.println(F("Can't set ITimer1. Select another freq. or timer"));
+
+#elif USE_TIMER_2
+
+  ITimer2.init();
+
+  if (ITimer2.attachInterrupt(HW_TIMER_INTERVAL_FREQ, TimerHandler))
+  {
+    Serial.print(F("Starting  ITimer2 OK, micros() = ")); Serial.println(micros());
+  }
+  else
+    Serial.println(F("Can't set ITimer2. Select another freq. or timer"));
+
+#elif USE_TIMER_3
+
+  ITimer3.init();
+
+  if (ITimer3.attachInterrupt(HW_TIMER_INTERVAL_FREQ, TimerHandler))
+  {
+    Serial.print(F("Starting  ITimer3 OK, micros() = ")); Serial.println(micros());
+  }
+  else
+    Serial.println(F("Can't set ITimer3. Select another freq. or timer"));
+
+#endif
+
+#endif
+
+
+  // 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
+  for (uint16_t i = 0; i < NUMBER_ISR_PWMS; i++)
+  {
+    //void setPWM(uint32_t pin, float frequency, float dutycycle
+    // , timer_callback_p StartCallback = nullptr, timer_callback_p StopCallback = nullptr)
+
+    // You can use this with PWM_Freq in Hz
+    ISR_PWM.setPWM(PWM_Pin[i], PWM_Freq[i], PWM_DutyCycle[i], irqCallbackStartFunc[i]);
+  }
+}
+
+void loop()
+{
+}