v1.0.0 for hardware-PWM on megaAVR boards

### Initial Releases v1.0.0

1. Initial coding to support **megaAVR boards, such as UNO WiFi Rev2, AVR_Nano_Every, etc.**, using `Arduino megaAVR` or `MegaCoreX` core
2. The hardware-based PWM channels using TimerB can generate very high frequencies.

CONTRIBUTING.md

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+## Contributing to megaAVR_PWM
+
+### Reporting Bugs
+
+Please report bugs in megaAVR_PWM if you find them.
+
+However, before reporting a bug please check through the following:
+
+* [Existing Open Issues](https://github.com/khoih-prog/megaAVR_PWM/issues) - someone might have already encountered this.
+
+If you don't find anything, please [open a new issue](https://github.com/khoih-prog/megaAVR_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 megaAVR` or `MegaCoreX` Core Version (e.g. Arduino megaAVR core v1.8.7 or MegaCoreX core v1.1.0)
+* 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 megaAVR Core Version 1.8.7
+OS: Ubuntu 20.04 LTS
+Linux xy-Inspiron-3593 5.15.0-52-generic #58~20.04.1-Ubuntu SMP Thu Oct 13 13:09:46 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. ...
+```
+
+### Additional context
+
+Add any other context about the problem here.
+
+---
+
+### 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/megaAVR_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!
+
+Please use the `astyle` to reformat the updated library code as follows (demo for Ubuntu Linux)
+
+1. Change directory to the library GitHub
+
+```
+xy@xy-Inspiron-3593:~$ cd Arduino/xy/megaAVR_PWM_GitHub/
+xy@xy-Inspiron-3593:~/Arduino/xy/megaAVR_PWM_GitHub$
+```
+
+2. Issue astyle command
+
+```
+xy@xy-Inspiron-3593:~/Arduino/xy/megaAVR_PWM_GitHub$ bash utils/restyle.sh
+```

changelog.md

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+# megaAVR_PWM Library
+
+[![arduino-library-badge](https://www.ardu-badge.com/badge/megaAVR_PWM.svg?)](https://www.ardu-badge.com/megaAVR_PWM)
+[![GitHub release](https://img.shields.io/github/release/khoih-prog/megaAVR_PWM.svg)](https://github.com/khoih-prog/megaAVR_PWM/releases)
+[![GitHub](https://img.shields.io/github/license/mashape/apistatus.svg)](https://github.com/khoih-prog/megaAVR_PWM/blob/main/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/megaAVR_PWM.svg)](http://github.com/khoih-prog/megaAVR_PWM/issues)
+
+---
+---
+
+## Table of Contents
+
+* [Changelog](#changelog)
+  * [Initial Releases v1.0.0](#Initial-Releases-v100)
+
+---
+---
+
+## Changelog
+
+### Initial Releases v1.0.0
+
+1. Initial coding to support **megaAVR boards, such as UNO WiFi Rev2, AVR_Nano_Every, etc.**, using `Arduino megaAVR` or `MegaCoreX` core
+2. The hardware-based PWM channels using TimerB can generate very high frequencies.
+
+---
+---
+
+## Copyright
+
+Copyright 2022- Khoi Hoang
+
+

examples/PWM_Basic/PWM_Basic.ino

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+/****************************************************************************************************************************
+  PWM_Basic.ino
+
+  For Arduino megaAVR ATMEGA4809-based boards (UNO WiFi Rev2, NANO_EVERY, etc. )
+  Written by Khoi Hoang
+
+  Built by Khoi Hoang https://github.com/khoih-prog/megaAVR_PWM
+  Licensed under MIT license
+
+  This is pure hardware-based PWM
+*****************************************************************************************************************************/
+/******************************************************************************************************************************
+  Pins can be used for hardware-PWM
+  // For ATmega4809 (Nano Every, Uno WiFi Rev2, etc.)
+  TCA0 (16-bit) used by PWM generation on pins 5, 9 and 10
+  TCB0 (16-bit) used by PWM generation on pin 6
+  TCB1 (16-bit) used by PWM generation on pin 3
+  TCB2 (16-bit)
+  TCB3 (16-bit)
+  ////////////////////////////////////////////
+  // For ATmega4809 (Nano Every, Uno WiFi Rev2, etc.)
+  Pin  3 => TIMERB1,       //  3 PF5,  8-bit PWM, 16-bit counter
+  Pin  5 => TIMERA0,       //  5 PB2, 16-bit PWM, 16-bit counter
+  Pin  6 => TIMERB0,       //  6 PF4,  8-bit PWM, 16-bit counter
+  Pin  9 => TIMERA0,       //  9 PB0, 16-bit PWM, 16-bit counter
+  Pin 10 => TIMERA0,       // 10 PB1, 16-bit PWM, 16-bit counter
+  ////////////////////////////////////////////
+******************************************************************************************************************************/
+
+#define _PWM_LOGLEVEL_        4
+
+#include "megaAVR_PWM.h"
+
+#define USING_TIMERB        true
+
+#if USING_TIMERB
+  // Pins tested OK in Nano Every ATmega4809
+  #define pinToUse      3            // TimerB1, for higher frequencies, up to 100KHz
+  //#define pinToUse      6            // TimerB0, for higher frequencies, up to 100KHz
+#elif USING_ARDUINO_MEGA_AVR_CORE
+  // Pins tested OK in Nano Every ATmega4809 using Arduino megaAVR core
+  // TimerA0 somehow can't be used with MegaCoreX
+  #define pinToUse      5            // TimerA0, only accurate @ low frequencies (< 1KHz) because of low 250KHz clock
+  //#define pinToUse      9            // TimerA0, only accurate @ low frequencies (< 1KHz) because of low 250KHz clock
+  //#define pinToUse     10            // TimerA0, only accurate @ low frequencies (< 1KHz) because of low 250KHz clock
+#else
+  #error TimerA0 to be used with Arduino megaAVR Core
+#endif
+
+////////////////////////////////////////////
+
+//creates pwm instance
+megaAVR_PWM* PWM_Instance;
+
+float frequency;
+float dutyCycle;
+
+////////////////////////////////////////////
+
+void setup()
+{
+  Serial.begin(115200);
+
+  while (!Serial && millis() < 5000);
+
+  //delay(1000);
+
+  Serial.print(F("\nStarting PWM_Basic on "));
+  Serial.println(BOARD_NAME);
+  Serial.println(MEGA_AVR_PWM_VERSION);
+
+  //assigns PWM frequency of 1KHz and a duty cycle of 0%
+  PWM_Instance = new megaAVR_PWM(pinToUse, 1000, 0);
+}
+
+void loop()
+{
+#if USING_TIMERB
+  // Using higher Hz for TimerB, min is 980.34 Hz
+  frequency = 40000;
+  //frequency = 1000;
+#else
+  // Using much lower Hz for TimerA
+  frequency = 1000;
+#endif
+
+  dutyCycle = 30;
+
+  PWM_Instance->setPWM(pinToUse, frequency, dutyCycle);
+
+  delay(5000);
+  dutyCycle = 90;
+
+  PWM_Instance->setPWM(pinToUse, frequency, dutyCycle);
+
+  //while (true)
+  delay(5000);
+}

examples/PWM_DynamicDutyCycle/PWM_DynamicDutyCycle.ino

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+/****************************************************************************************************************************
+  PWM_DynamicDutyCycle.ino
+  For Arduino megaAVR ATMEGA4809-based boards (UNO WiFi Rev2, NANO_EVERY, etc. )
+  Written by Khoi Hoang
+
+  Built by Khoi Hoang https://github.com/khoih-prog/megaAVR_PWM
+  Licensed under MIT license
+
+  This is pure hardware-based PWM
+*****************************************************************************************************************************/
+/******************************************************************************************************************************
+  Pins can be used for hardware-PWM
+  // For ATmega4809 (Nano Every, Uno WiFi Rev2, etc.)
+  TCA0 (16-bit) used by PWM generation on pins 5, 9 and 10
+  TCB0 (16-bit) used by PWM generation on pin 6
+  TCB1 (16-bit) used by PWM generation on pin 3
+  TCB2 (16-bit)
+  TCB3 (16-bit)
+  ////////////////////////////////////////////
+  // For ATmega4809 (Nano Every, Uno WiFi Rev2, etc.)
+  Pin  3 => TIMERB1,       //  3 PF5,  8-bit PWM, 16-bit counter
+  Pin  5 => TIMERA0,       //  5 PB2, 16-bit PWM, 16-bit counter
+  Pin  6 => TIMERB0,       //  6 PF4,  8-bit PWM, 16-bit counter
+  Pin  9 => TIMERA0,       //  9 PB0, 16-bit PWM, 16-bit counter
+  Pin 10 => TIMERA0,       // 10 PB1, 16-bit PWM, 16-bit counter
+  ////////////////////////////////////////////
+******************************************************************************************************************************/
+
+#define _PWM_LOGLEVEL_        4
+
+#include "megaAVR_PWM.h"
+
+#define USING_TIMERB        true
+
+#if USING_TIMERB
+  // Pins tested OK in Nano Every ATmega4809
+  #define pinToUse      3            // TimerB1, for higher frequencies, up to 100KHz
+  //#define pinToUse      6            // TimerB0, for higher frequencies, up to 100KHz
+#elif USING_ARDUINO_MEGA_AVR_CORE
+  // Pins tested OK in Nano Every ATmega4809 using Arduino megaAVR core
+  // TimerA0 somehow can't be used with MegaCoreX
+  #define pinToUse      5            // TimerA0, only accurate @ low frequencies (< 1KHz) because of low 250KHz clock
+  //#define pinToUse      9            // TimerA0, only accurate @ low frequencies (< 1KHz) because of low 250KHz clock
+  //#define pinToUse     10            // TimerA0, only accurate @ low frequencies (< 1KHz) because of low 250KHz clock
+#else
+  #error TimerA0 to be used with Arduino megaAVR Core
+#endif
+
+////////////////////////////////////////////
+
+//creates pwm instance
+megaAVR_PWM* PWM_Instance;
+
+float frequency;
+float dutyCycle;
+
+char dashLine[] = "=====================================================================================";
+
+void printPWMInfo(megaAVR_PWM* PWM_Instance)
+{
+  Serial.println(dashLine);
+  Serial.print("Actual data: pin = ");
+  Serial.print(PWM_Instance->getPin());
+  Serial.print(", PWM DC = ");
+  Serial.print(PWM_Instance->getActualDutyCycle());
+  Serial.print(", PWMPeriod = ");
+  Serial.print(PWM_Instance->getPWMPeriod());
+  Serial.print(", PWM Freq (Hz) = ");
+  Serial.println(PWM_Instance->getActualFreq(), 4);
+  Serial.println(dashLine);
+}
+
+void setup()
+{
+  Serial.begin(115200);
+
+  while (!Serial && millis() < 5000);
+
+  //delay(1000);
+
+  Serial.print(F("\nStarting PWM_DynamicDutyCycle on "));
+  Serial.println(BOARD_NAME);
+  Serial.println(MEGA_AVR_PWM_VERSION);
+
+  frequency = 5000;
+
+  PWM_Instance = new megaAVR_PWM(pinToUse, frequency, 50);
+
+  if (PWM_Instance)
+  {
+    if (!PWM_Instance->setPWM())
+    {
+      Serial.println(F("Stop here"));
+
+      // stop here
+      while (true)
+        delay(1000);
+    }
+  }
+
+  Serial.println(dashLine);
+}
+
+void loop()
+{
+  //frequency = 200000.0f;
+  frequency = 1000.0f;
+
+  dutyCycle = 90.0f;
+
+  Serial.print(F("Change PWM DutyCycle to "));
+  Serial.println(dutyCycle);
+  PWM_Instance->setPWM(pinToUse, frequency, dutyCycle);
+
+  printPWMInfo(PWM_Instance);
+
+  delay(5000);
+  dutyCycle = 10.0f;
+
+  Serial.print(F("Change PWM DutyCycle to "));
+  Serial.println(dutyCycle);
+  PWM_Instance->setPWM(pinToUse, frequency, dutyCycle);
+  printPWMInfo(PWM_Instance);
+
+  delay(5000);
+}