SAMD_Slow_PWM Library

Important Change from v1.2.0
Why do we need this SAMD_Slow_PWM library
- Features
- Why using ISR-based PWM is better
- Currently supported Boards
- Important Notes about ISR
Changelog
Prerequisites
Installation
- Use Arduino Library Manager
- Manual Install
- VS Code & PlatformIO
Packages' Patches
- 1. For Arduino SAMD boards
  - For core version v1.8.10+
  - For core version v1.8.9-
- 2. For Adafruit SAMD boards
- 3. For Seeeduino SAMD boards
- 4. For SparkFun SAMD boards
HOWTO Fix Multiple Definitions Linker Error
Usage
- 1. Init Hardware Timer
- 2. Set PWM Frequency, dutycycle, attach irqCallbackStartFunc and irqCallbackStopFunc functions
Examples
- For SAMD21
- For SAMD51
Example SAMD51 ISR_16_PWMs_Array_Complex
Debug Terminal Output Samples
- 1. ISR_4_PWMs_Array_Complex on SAMD_NANO_33_IOT
- 2. ISR_16_PWMs_Array_Complex on ITSYBITSY_M4
- 3. ISR_4_PWMs_Array_Complex on SEEED_XIAO_M0
- 4. ISR_Modify_PWM on SAMD_NANO_33_IOT
- 5. ISR_Changing_PWM on SAMD_NANO_33_IOT
- 6. ISR_Modify_PWM on ITSYBITSY_M4
- 7. ISR_Changing_PWM on ITSYBITSY_M4
Debug
Troubleshooting
Issues
TO DO
DONE
Contributions and Thanks
Contributing
License
Copyright

Important Change from v1.2.0

Please have a look at HOWTO Fix Multiple Definitions Linker Error

As more complex calculation and check inside ISR are introduced from v1.2.0, there are consequences as follows

For SAMD21 (slower) => using min 50uS and max 4 PWM channels

// Use 50uS for slow SAMD21
#define HW_TIMER_INTERVAL_US      50L

For SAMD51 (faster) => using min 20uS and max 16 PWM channels

// Use 30uS for faster SAMD51
#define HW_TIMER_INTERVAL_US      20L

You certainly can modify to use better values according to your board and use-case, just remember to test and reverse to conservative values if crash happens.

Why do we need this SAMD_Slow_PWM library

Features

This library enables you to use Hardware Timers on SAMD21/SAMD51 boards such as NANO_33_IOT, ITSYBITSY_M4, SEEED_XIAO_M0, SparkFun_SAMD51_Thing_Plus, etc., to create and output PWM to pins. Because this library doesn't use the powerful hardware-controlled PWM with limitations, the maximum PWM frequency is currently limited at 1000Hz, which is suitable for many real-life applications.

This library enables you to use Interrupt from Hardware Timers on SAMD21/SAMD51 boards to create and output PWM to pins. It now supports 16 ISR-based synchronized PWM channels, while consuming only 1 Hardware Timer. PWM interval can be very long (uint32_t millisecs). The most important feature is they're ISR-based PWM channels. Therefore, their executions are not blocked by bad-behaving functions or tasks. This important feature is absolutely necessary for mission-critical tasks. These hardware PWM channels, using interrupt, still work even if other functions are blocking. Moreover, they are much more precise (certainly depending on clock frequency accuracy) than other software PWM using millis() or micros(). That's necessary if you need to measure some data requiring better accuracy.

As Hardware Timers are rare, and very precious assets of any board, this library now enables you to use up to 16 ISR-based synchronized PWM channels, while consuming only 1 Hardware Timer. Timers' interval is very long (ulong millisecs).

Now with these new 16 ISR-based PWM-channels, the maximum interval is practically unlimited (limited only by unsigned long milliseconds) while the accuracy is nearly perfect compared to software timers.

The most important feature is they're ISR-based PWM channels. Therefore, their executions are not blocked by bad-behaving functions / tasks. This important feature is absolutely necessary for mission-critical tasks.

The SAMD51 PWMs_Array_Complex example will demonstrate the nearly perfect accuracy, compared to software PWM, by printing the actual period / duty-cycle in microsecs of each of PWM-channels.

Being ISR-based PWM, their executions are not blocked by bad-behaving functions / tasks, such as connecting to WiFi, Internet or Blynk services. You can also have many (up to 16) timers to use.

This non-being-blocked important feature is absolutely necessary for mission-critical tasks.

You'll see software-based SimpleTimer is blocked while system is connecting to WiFi / Internet / Blynk, as well as by blocking task in loop(), using delay() function as an example. The elapsed time then is very unaccurate

Why using ISR-based PWM is better

Imagine you have a system with a mission-critical function, measuring water level and control the sump pump or doing something much more important. You normally use a software timer to poll, or even place the function in loop(). But what if another function is blocking the loop() or setup().

So your function might not be executed, and the result would be disastrous.

You'd prefer to have your function called, no matter what happening with other functions (busy loop, bug, etc.).

The correct choice is to use a Hardware Timer with Interrupt to call your function.

These hardware timers, using interrupt, still work even if other functions are blocking. Moreover, they are much more precise (certainly depending on clock frequency accuracy) than other software timers using millis() or micros(). That's necessary if you need to measure some data requiring better accuracy.

Functions using normal software timers, relying on loop() and calling millis(), won't work if the loop() or setup() is blocked by certain operation. For example, certain function is blocking while it's connecting to WiFi or some services.

The catch is your function is now part of an ISR (Interrupt Service Routine), and must be lean / mean, and follow certain rules. More to read on:

HOWTO Attach Interrupt

Currently supported Boards

Arduino SAMD21 (ZERO, MKR, NANO_33_IOT, etc.).
Adafruit SAM21 (Itsy-Bitsy M0, Metro M0, Feather M0, Gemma M0, etc.).
Adafruit SAM51 (Itsy-Bitsy M4, Metro M4, Grand Central M4, Feather M4 Express, etc.).
Seeeduino SAMD21/SAMD51 boards (SEEED_WIO_TERMINAL, SEEED_FEMTO_M0, SEEED_XIAO_M0, Wio_Lite_MG126, WIO_GPS_BOARD, SEEEDUINO_ZERO, SEEEDUINO_LORAWAN, SEEED_GROVE_UI_WIRELESS, etc.)
Sparkfun SAMD21 boards such as SparkFun_RedBoard_Turbo, SparkFun_Qwiic_Micro, etc.
Sparkfun SAMD51 boards such as SparkFun_SAMD51_Thing_Plus, SparkFun_SAMD51_MicroMod, etc.

Important Notes about ISR

Inside the attached function, delay() won’t work and the value returned by millis() will not increment. Serial data received while in the function may be lost. You should declare as volatile any variables that you modify within the attached function.
Typically global variables are used to pass data between an ISR and the main program. To make sure variables shared between an ISR and the main program are updated correctly, declare them as volatile.

Prerequisites

Arduino IDE 1.8.19+ for Arduino.
Arduino SAMD core 1.8.13+ for SAMD ARM Cortex-M0+ boards.
Adafruit SAMD core 1.7.11+ for SAMD ARM Cortex-M0+ and M4 boards (Nano 33 IoT, etc.).
Seeeduino SAMD core 1.8.3+ for SAMD21/SAMD51 boards (XIAO M0, Wio Terminal, etc.).
Sparkfun SAMD core 1.8.3+ for SAMD21/SAMD51 boards (SparkFun_RedBoard_Turbo, SparkFun_SAMD51_Thing_Plus, etc.).
To use with certain example

SimpleTimer library to use with some examples.

Installation

Use Arduino Library Manager

The best and easiest way is to use Arduino Library Manager. Search for SAMD_Slow_PWM, then select / install the latest version. You can also use this link for more detailed instructions.

Manual Install

Another way to install is to:

Navigate to SAMD_Slow_PWM page.
Download the latest release SAMD_Slow_PWM-main.zip.
Extract the zip file to SAMD_Slow_PWM-main directory
Copy whole SAMD_Slow_PWM-main folder to Arduino libraries' directory such as ~/Arduino/libraries/.

VS Code & PlatformIO

Install VS Code
Install PlatformIO
Install SAMD_Slow_PWM library by using Library Manager. Search for SAMD_Slow_PWM in Platform.io Author's Libraries
Use included platformio.ini file from examples to ensure that all dependent libraries will installed automatically. Please visit documentation for the other options and examples at Project Configuration File

Packages' Patches

1. For Arduino SAMD boards

To be able to compile without error and automatically detect and display BOARD_NAME on Arduino SAMD (Nano-33-IoT, etc) boards, you have to copy the whole Arduino SAMD Packages_Patches directory into Arduino SAMD directory (~/.arduino15/packages/arduino/hardware/samd/1.8.13).

For core version v1.8.10+

Supposing the Arduino SAMD version is 1.8.13. Now only one file must be copied into the directory:

~/.arduino15/packages/arduino/hardware/samd/1.8.13/platform.txt

Whenever a new version is installed, remember to copy this files into the new version directory. For example, new version is x.yy.zz

This file must be copied into the directory:

~/.arduino15/packages/arduino/hardware/samd/x.yy.zz/platform.txt

For core version v1.8.9-

Supposing the Arduino SAMD version is 1.8.9. These files must be copied into the directory:

~/.arduino15/packages/arduino/hardware/samd/1.8.9/platform.txt
~/.arduino15/packages/arduino/hardware/samd/1.8.9/cores/arduino/Arduino.h

Whenever a new version is installed, remember to copy these files into the new version directory. For example, new version is x.yy.z

These files must be copied into the directory:

~/.arduino15/packages/arduino/hardware/samd/x.yy.z/platform.txt
~/.arduino15/packages/arduino/hardware/samd/x.yy.z/cores/arduino/Arduino.h

This is mandatory to fix the notorious Arduino SAMD compiler error. See Improve Arduino compatibility with the STL (min and max macro)

 ...\arm-none-eabi\include\c++\7.2.1\bits\stl_algobase.h:243:56: error: macro "min" passed 3 arguments, but takes just 2
     min(const _Tp& __a, const _Tp& __b, _Compare __comp)

Whenever the above-mentioned compiler error issue is fixed with the new Arduino SAMD release, you don't need to copy the Arduino.h file anymore.

2. For Adafruit SAMD boards

To be able to compile without error and automatically detect and display BOARD_NAME on Adafruit SAMD (Itsy-Bitsy M4, etc) boards, you have to copy the files in Adafruit SAMD Packages_Patches into Adafruit samd directory (~/.arduino15/packages/adafruit/hardware/samd/1.7.11).

Supposing the Adafruit SAMD core version is 1.7.11. This file must be copied into the directory:

~/.arduino15/packages/adafruit/hardware/samd/1.7.11/platform.txt
~/.arduino15/packages/adafruit/hardware/samd/1.7.11/cores/arduino/Print.h
~/.arduino15/packages/adafruit/hardware/samd/1.7.11/cores/arduino/Print.cpp

Whenever a new version is installed, remember to copy this file into the new version directory. For example, new version is x.yy.zz This file must be copied into the directory:

~/.arduino15/packages/adafruit/hardware/samd/x.yy.zz/platform.txt
~/.arduino15/packages/adafruit/hardware/samd/x.yy.zz/cores/arduino/Print.h
~/.arduino15/packages/adafruit/hardware/samd/x.yy.zz/cores/arduino/Print.cpp

3. For Seeeduino SAMD boards

To be able to compile without error and automatically detect and display BOARD_NAME on Seeeduino SAMD (XIAO M0, Wio Terminal, etc) boards, you have to copy the files in Seeeduino SAMD Packages_Patches into Seeeduino samd directory (~/.arduino15/packages/Seeeduino/hardware/samd/1.8.3).

Supposing the Seeeduino SAMD core version is 1.8.3. This file must be copied into the directory:

~/.arduino15/packages/Seeeduino/hardware/samd/1.8.3/platform.txt
~/.arduino15/packages/Seeeduino/hardware/samd/1.8.3/cores/arduino/Arduino.h
~/.arduino15/packages/Seeeduino/hardware/samd/1.8.3/cores/arduino/Print.h
~/.arduino15/packages/Seeeduino/hardware/samd/1.8.3/cores/arduino/Print.cpp

Whenever a new version is installed, remember to copy this file into the new version directory. For example, new version is x.yy.zz This file must be copied into the directory:

~/.arduino15/packages/Seeeduino/hardware/samd/x.yy.zz/platform.txt
~/.arduino15/packages/Seeeduino/hardware/samd/x.yy.zz/cores/arduino/Arduino.h
~/.arduino15/packages/Seeeduino/hardware/samd/x.yy.zz/cores/arduino/Print.h
~/.arduino15/packages/Seeeduino/hardware/samd/x.yy.zz/cores/arduino/Print.cpp

4. For SparkFun SAMD boards

To be able to compile without error and automatically detect and display BOARD_NAME on SparkFun SAMD (XIAO SparkFun_RedBoard_Turbo, SparkFun_SAMD51_Thing_Plus, etc) boards, you have to copy the file SparkFun SAMD Packages_Patches into SparkFun samd directory (~/.arduino15/packages/SparkFun/hardware/samd/1.8.3).

Supposing the SparkFun SAMD core version is 1.8.3. This file must be copied into the directory:

~/.arduino15/packages/SparkFun/hardware/samd/1.8.3/cores/arduino/Print.h
~/.arduino15/packages/SparkFun/hardware/samd/1.8.3/cores/arduino/Print.cpp
~/.arduino15/packages/SparkFun/hardware/samd/1.8.3/cores/arduino51/Print.h
~/.arduino15/packages/SparkFun/hardware/samd/1.8.3/cores/arduino51/Print.cpp

Whenever a new version is installed, remember to copy this file into the new version directory. For example, new version is x.yy.zz This file must be copied into the directory:

~/.arduino15/packages/SparkFun/hardware/samd/x.yy.zz/cores/arduino/Print.h
~/.arduino15/packages/SparkFun/hardware/samd/x.yy.zz/cores/arduino/Print.cpp
~/.arduino15/packages/SparkFun/hardware/samd/x.yy.zz/cores/arduino51/Print.h
~/.arduino15/packages/SparkFun/hardware/samd/x.yy.zz/cores/arduino51/Print.cpp

HOWTO Fix `Multiple Definitions` Linker Error

The current library implementation, using xyz-Impl.h instead of standard xyz.cpp, possibly creates certain Multiple Definitions Linker error in certain use cases.

You can include this .hpp file

// Can be included as many times as necessary, without `Multiple Definitions` Linker Error
#include "SAMD_Slow_PWM.hpp"     //https://github.com/khoih-prog/SAMD_Slow_PWM

in many files. But be sure to use the following .h file in just 1 .h, .cpp or .ino file, which must not be included in any other file, to avoid Multiple Definitions Linker Error

// To be included only in main(), .ino with setup() to avoid `Multiple Definitions` Linker Error
#include "SAMD_Slow_PWM.h"           //https://github.com/khoih-prog/SAMD_Slow_PWM

Check the new SAMD21 multiFileProject example or SAMD51 multiFileProject example for a HOWTO demo.

Have a look at the discussion in Different behaviour using the src_cpp or src_h lib #80

Usage

Before using any Timer for a PWM channel, you have to make sure the Timer has not been used by any other purpose.

1. Init Hardware Timer

// Depending on the board, you can select SAMD21 Hardware Timer from TC3-TCC
// SAMD21 Hardware Timer from TC3 or TCC
// SAMD51 Hardware Timer only TC3
SAMDTimer ITimer0(TIMER_TC3);

// You can only select SAMD51 Hardware Timer TC3
// Init SAMD timer TIMER_TC3
//SAMDTimer ITimer(TIMER_TC3);

// Init SAMD_Slow_PWM
SAMD_Slow_PWM ISR_PWM;

2. Set PWM Frequency, dutycycle, attach irqCallbackStartFunc and irqCallbackStopFunc functions

void irqCallbackStartFunc()
{

}

void irqCallbackStopFunc()
{

}

void setup()
{
  ....
  
  // You can use this with PWM_Freq in Hz
    ISR_PWM.setPWM(PWM_Pin, PWM_Freq, PWM_DutyCycle, irqCallbackStartFunc, irqCallbackStopFunc);
                   
  ....                 
}

Examples:

For SAMD21

For SAMD51

Example SAMD51 ISR_16_PWMs_Array_Complex

SAMD_Slow_PWM/examples/SAMD51/ISR_16_PWMs_Array_Complex/ISR_16_PWMs_Array_Complex.ino

Lines 16 to 583 in da5c3ce

    
           #if !( defined(__SAMD51__) || defined(__SAMD51J20A__) || defined(__SAMD51J19A__) || defined(__SAMD51G19A__) || defined(__SAMD51P19A__) ) 
        
             #error This code is designed to run on SAMD51 platform! Please check your Tools->Board setting. 
        
           #endif 
        
           // These define's must be placed at the beginning before #include "ESP32_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 
        
           #define MAX_SAMD_PWM_FREQ            1000 
        
           // To be included only in main(), .ino with setup() to avoid `Multiple Definitions` Linker Error 
        
           #include "SAMD_Slow_PWM.h" 
        
           #define boolean     bool 
        
           #include <SimpleTimer.h>              // https://github.com/jfturcot/SimpleTimer 
        
           #define LED_OFF             LOW 
        
           #define LED_ON              HIGH 
        
           #ifndef LED_BUILTIN 
        
             #define LED_BUILTIN       13 
        
           #endif 
        
           #ifndef LED_BLUE 
        
             #define LED_BLUE          2 
        
           #endif 
        
           #ifndef LED_RED 
        
             #define LED_RED           3 
        
           #endif 
        
           #define HW_TIMER_INTERVAL_US      20L 
        
           uint64_t startMicros = 0; 
        
           // You can only select SAMD51 Hardware Timer TC3 
        
           // Init SAMD timer TIMER_TC3 
        
           SAMDTimer ITimer(TIMER_TC3); 
        
           // Init SAMD_Slow_PWM 
        
           SAMD_Slow_PWM ISR_PWM; 
        
           ////////////////////////////////////////////////////// 
        
           void TimerHandler() 
        
           { 
        
             ISR_PWM.run(); 
        
           } 
        
           ///////////////////////////////////////////////// 
        
           #define NUMBER_ISR_PWMS         16 
        
           #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 
        
           #define PIN_D7      7 
        
           #define PIN_D8      8 
        
           #define PIN_D9      9 
        
           #define PIN_D10     10 
        
           #define PIN_D11     11 
        
           #define PIN_D12     12 
        
           typedef void (*irqCallback)  (); 
        
           ////////////////////////////////////////////////////// 
        
           #define USE_COMPLEX_STRUCT      true 
        
           #define USING_PWM_FREQUENCY     true 
        
           ////////////////////////////////////////////////////// 
        
           #if USE_COMPLEX_STRUCT 
        
           typedef struct 
        
           { 
        
             uint32_t      PWM_Pin; 
        
             irqCallback   irqCallbackStartFunc; 
        
             irqCallback   irqCallbackStopFunc; 
        
           #if USING_PWM_FREQUENCY   
        
             float         PWM_Freq; 
        
           #else   
        
             uint32_t      PWM_Period; 
        
           #endif 
        
             float         PWM_DutyCycle; 
        
             uint64_t      deltaMicrosStart; 
        
             uint64_t      previousMicrosStart; 
        
             uint64_t      deltaMicrosStop; 
        
             uint64_t      previousMicrosStop; 
        
           } ISR_PWM_Data; 
        
           // In NRF52, avoid doing something fancy in ISR, for example Serial.print() 
        
           // 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 doingSomethingStart(int index); 
        
           void doingSomethingStop(int index); 
        
           #else   // #if USE_COMPLEX_STRUCT 
        
           volatile unsigned long deltaMicrosStart    [] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; 
        
           volatile unsigned long previousMicrosStart [] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; 
        
           volatile unsigned long deltaMicrosStop     [] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; 
        
           volatile unsigned long previousMicrosStop  [] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; 
        
           // You can assign pins here. Be carefull to select good pin to use or crash, e.g pin 6-11 
        
           uint32_t PWM_Pin[] = 
        
           { 
        
              LED_BUILTIN,   LED_BLUE,   LED_RED, PIN_D0, PIN_D1,  PIN_D2,  PIN_D3,  PIN_D4, 
        
                   PIN_D5,     PIN_D6,    PIN_D7, PIN_D8, PIN_D9, PIN_D10, PIN_D11, PIN_D12 
        
           }; 
        
           // You can assign any interval for any timer here, in microseconds 
        
           uint32_t PWM_Period[] = 
        
           { 
        
             10000000,    5000000,   333333,   250000,   200000,   166667,   142857,   125000, 
        
               111111,    100000,     66667,    50000,    40000,    33333,    25000,    20000 
        
           }; 
        
           // 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, 
        
             9.0f, 10.0f, 15.0f, 20.0f, 25.0f, 30.0f, 40.0f, 50.0f 
        
           }; 
        
           // You can assign any interval for any timer here, in milliseconds 
        
           float PWM_DutyCycle[] = 
        
           { 
        
              5.00, 10.00, 20.00, 30.00, 40.00, 45.00, 50.00, 55.00, 
        
             60.00, 65.00, 70.00, 75.00, 80.00, 85.00, 90.00, 95.00 
        
           }; 
        
           void doingSomethingStart(int index) 
        
           { 
        
             unsigned long currentMicros  = micros(); 
        
             deltaMicrosStart[index]    = currentMicros - previousMicrosStart[index]; 
        
             previousMicrosStart[index] = currentMicros; 
        
           } 
        
           void doingSomethingStop(int index) 
        
           { 
        
             unsigned long currentMicros  = micros(); 
        
             // Count from start to stop PWM pulse 
        
             deltaMicrosStop[index]    = currentMicros - previousMicrosStart[index]; 
        
             previousMicrosStop[index] = currentMicros; 
        
           } 
        
           #endif    // #if USE_COMPLEX_STRUCT 
        
           //////////////////////////////////// 
        
           // Shared 
        
           //////////////////////////////////// 
        
           void doingSomethingStart0() 
        
           { 
        
             doingSomethingStart(0); 
        
           } 
        
           void doingSomethingStart1() 
        
           { 
        
             doingSomethingStart(1); 
        
           } 
        
           void doingSomethingStart2() 
        
           { 
        
             doingSomethingStart(2); 
        
           } 
        
           void doingSomethingStart3() 
        
           { 
        
             doingSomethingStart(3); 
        
           } 
        
           void doingSomethingStart4() 
        
           { 
        
             doingSomethingStart(4); 
        
           } 
        
           void doingSomethingStart5() 
        
           { 
        
             doingSomethingStart(5); 
        
           } 
        
           void doingSomethingStart6() 
        
           { 
        
             doingSomethingStart(6); 
        
           } 
        
           void doingSomethingStart7() 
        
           { 
        
             doingSomethingStart(7); 
        
           } 
        
           void doingSomethingStart8() 
        
           { 
        
             doingSomethingStart(8); 
        
           } 
        
           void doingSomethingStart9() 
        
           { 
        
             doingSomethingStart(9); 
        
           } 
        
           void doingSomethingStart10() 
        
           { 
        
             doingSomethingStart(10); 
        
           } 
        
           void doingSomethingStart11() 
        
           { 
        
             doingSomethingStart(11); 
        
           } 
        
           void doingSomethingStart12() 
        
           { 
        
             doingSomethingStart(12); 
        
           } 
        
           void doingSomethingStart13() 
        
           { 
        
             doingSomethingStart(13); 
        
           } 
        
           void doingSomethingStart14() 
        
           { 
        
             doingSomethingStart(14); 
        
           } 
        
           void doingSomethingStart15() 
        
           { 
        
             doingSomethingStart(15); 
        
           } 
        
           ////////////////////////////////////////////////////// 
        
           void doingSomethingStop0() 
        
           { 
        
             doingSomethingStop(0); 
        
           } 
        
           void doingSomethingStop1() 
        
           { 
        
             doingSomethingStop(1); 
        
           } 
        
           void doingSomethingStop2() 
        
           { 
        
             doingSomethingStop(2); 
        
           } 
        
           void doingSomethingStop3() 
        
           { 
        
             doingSomethingStop(3); 
        
           } 
        
           void doingSomethingStop4() 
        
           { 
        
             doingSomethingStop(4); 
        
           } 
        
           void doingSomethingStop5() 
        
           { 
        
             doingSomethingStop(5); 
        
           } 
        
           void doingSomethingStop6() 
        
           { 
        
             doingSomethingStop(6); 
        
           } 
        
           void doingSomethingStop7() 
        
           { 
        
             doingSomethingStop(7); 
        
           } 
        
           void doingSomethingStop8() 
        
           { 
        
             doingSomethingStop(8); 
        
           } 
        
           void doingSomethingStop9() 
        
           { 
        
             doingSomethingStop(9); 
        
           } 
        
           void doingSomethingStop10() 
        
           { 
        
             doingSomethingStop(10); 
        
           } 
        
           void doingSomethingStop11() 
        
           { 
        
             doingSomethingStop(11); 
        
           } 
        
           void doingSomethingStop12() 
        
           { 
        
             doingSomethingStop(12); 
        
           } 
        
           void doingSomethingStop13() 
        
           { 
        
             doingSomethingStop(13); 
        
           } 
        
           void doingSomethingStop14() 
        
           { 
        
             doingSomethingStop(14); 
        
           } 
        
           void doingSomethingStop15() 
        
           { 
        
             doingSomethingStop(15); 
        
           } 
        
           ////////////////////////////////////////////////////// 
        
           #if USE_COMPLEX_STRUCT 
        
             #if USING_PWM_FREQUENCY 
        
             ISR_PWM_Data curISR_PWM_Data[] = 
        
             { 
        
               // pin, irqCallbackStartFunc, irqCallbackStopFunc, PWM_Freq, PWM_DutyCycle, deltaMicrosStart, previousMicrosStart, deltaMicrosStop, previousMicrosStop 
        
               { LED_BUILTIN,  doingSomethingStart0,    doingSomethingStop0,    1.0,   5.0, 0, 0, 0, 0 }, 
        
               { LED_BLUE,     doingSomethingStart1,    doingSomethingStop1,    2.0,  10.0, 0, 0, 0, 0 }, 
        
               { LED_RED,      doingSomethingStart2,    doingSomethingStop2,    3.0,  20.0, 0, 0, 0, 0 }, 
        
               { PIN_D0,       doingSomethingStart3,    doingSomethingStop3,    4.0,  30.0, 0, 0, 0, 0 }, 
        
               { PIN_D1,       doingSomethingStart4,    doingSomethingStop4,    5.0,  40.0, 0, 0, 0, 0 }, 
        
               { PIN_D2,       doingSomethingStart5,    doingSomethingStop5,    6.0,  45.0, 0, 0, 0, 0 }, 
        
               { PIN_D3,       doingSomethingStart6,    doingSomethingStop6,    7.0,  50.0, 0, 0, 0, 0 }, 
        
               { PIN_D4,       doingSomethingStart7,    doingSomethingStop7,    8.0,  55.0, 0, 0, 0, 0 }, 
        
               { PIN_D5,       doingSomethingStart8,    doingSomethingStop8,    9.0,  60.0, 0, 0, 0, 0 }, 
        
               { PIN_D6,       doingSomethingStart9,    doingSomethingStop9,   10.0,  65.0, 0, 0, 0, 0 }, 
        
               { PIN_D7,       doingSomethingStart10,   doingSomethingStop10,  15.0,  70.0, 0, 0, 0, 0 }, 
        
               { PIN_D8,       doingSomethingStart11,   doingSomethingStop11,  20.0,  75.0, 0, 0, 0, 0 }, 
        
               { PIN_D9,       doingSomethingStart12,   doingSomethingStop12,  25.0,  80.0, 0, 0, 0, 0 }, 
        
               { PIN_D10,      doingSomethingStart13,   doingSomethingStop13,  30.0,  85.0, 0, 0, 0, 0 }, 
        
               { PIN_D11,      doingSomethingStart14,   doingSomethingStop14,  40.0,  90.0, 0, 0, 0, 0 }, 
        
               { PIN_D12,      doingSomethingStart15,   doingSomethingStop15,  50.0,  95.0, 0, 0, 0, 0 } 
        
             }; 
        
             #else   // #if USING_PWM_FREQUENCY 
        
             ISR_PWM_Data curISR_PWM_Data[] = 
        
             { 
        
               // pin, irqCallbackStartFunc, irqCallbackStopFunc, PWM_Period, PWM_DutyCycle, deltaMicrosStart, previousMicrosStart, deltaMicrosStop, previousMicrosStop 
        
               { LED_BUILTIN,  doingSomethingStart0,     doingSomethingStop0,   1000000, 5.0, 0, 0, 0, 0 }, 
        
               { LED_BLUE,     doingSomethingStart1,     doingSomethingStop1,    500000, 10.0, 0, 0, 0, 0 }, 
        
               { LED_RED,      doingSomethingStart2,     doingSomethingStop2,    333333, 20.0, 0, 0, 0, 0 }, 
        
               { PIN_D0,       doingSomethingStart3,     doingSomethingStop3,    250000, 30.0, 0, 0, 0, 0 }, 
        
               { PIN_D1,       doingSomethingStart4,     doingSomethingStop4,    200000, 40.0, 0, 0, 0, 0 }, 
        
               { PIN_D2,       doingSomethingStart5,     doingSomethingStop5,    166667, 45.0, 0, 0, 0, 0 }, 
        
               { PIN_D3,       doingSomethingStart6,     doingSomethingStop6,    142857, 50.0, 0, 0, 0, 0 }, 
        
               { PIN_D4,       doingSomethingStart7,     doingSomethingStop7,    125000, 55.0, 0, 0, 0, 0 }, 
        
               { PIN_D5,       doingSomethingStart8,     doingSomethingStop8,    111111, 60.0, 0, 0, 0, 0 }, 
        
               { PIN_D6,       doingSomethingStart9,     doingSomethingStop9,    100000, 65.0, 0, 0, 0, 0 }, 
        
               { PIN_D7,       doingSomethingStart10,    doingSomethingStop10,    66667, 70.0, 0, 0, 0, 0 }, 
        
               { PIN_D8,       doingSomethingStart11,    doingSomethingStop11,    50000, 75.0, 0, 0, 0, 0 }, 
        
               { PIN_D9,       doingSomethingStart12,    doingSomethingStop12,    40000, 80.0, 0, 0, 0, 0 }, 
        
               { PIN_D10,      doingSomethingStart13,    doingSomethingStop13,    33333, 85.0, 0, 0, 0, 0 }, 
        
               { PIN_D11,      doingSomethingStart14,    doingSomethingStop14,    25000, 90.0, 0, 0, 0, 0 }, 
        
               { PIN_D12,      doingSomethingStart15,    doingSomethingStop15,    20000, 95.0, 0, 0, 0, 0 } 
        
             }; 
        
             #endif  // #if USING_PWM_FREQUENCY 
        
           void doingSomethingStart(int index) 
        
           { 
        
             unsigned long currentMicros  = micros(); 
        
             curISR_PWM_Data[index].deltaMicrosStart    = currentMicros - curISR_PWM_Data[index].previousMicrosStart; 
        
             curISR_PWM_Data[index].previousMicrosStart = currentMicros; 
        
           } 
        
           void doingSomethingStop(int index) 
        
           { 
        
             unsigned long currentMicros  = micros(); 
        
             //curISR_PWM_Data[index].deltaMicrosStop     = currentMicros - curISR_PWM_Data[index].previousMicrosStop; 
        
             // Count from start to stop PWM pulse 
        
             curISR_PWM_Data[index].deltaMicrosStop     = currentMicros - curISR_PWM_Data[index].previousMicrosStart; 
        
             curISR_PWM_Data[index].previousMicrosStop  = currentMicros; 
        
           } 
        
           #else   // #if USE_COMPLEX_STRUCT 
        
           irqCallback irqCallbackStartFunc[] = 
        
           { 
        
             doingSomethingStart0,  doingSomethingStart1,  doingSomethingStart2,  doingSomethingStart3, 
        
             doingSomethingStart4,  doingSomethingStart5,  doingSomethingStart6,  doingSomethingStart7, 
        
             doingSomethingStart8,  doingSomethingStart9,  doingSomethingStart10, doingSomethingStart11, 
        
             doingSomethingStart12, doingSomethingStart13, doingSomethingStart14, doingSomethingStart15 
        
           }; 
        
           irqCallback irqCallbackStopFunc[] = 
        
           { 
        
             doingSomethingStop0,  doingSomethingStop1,  doingSomethingStop2,  doingSomethingStop3, 
        
             doingSomethingStop4,  doingSomethingStop5,  doingSomethingStop6,  doingSomethingStop7, 
        
             doingSomethingStop8,  doingSomethingStop9,  doingSomethingStop10, doingSomethingStop11, 
        
             doingSomethingStop12, doingSomethingStop13, doingSomethingStop14, doingSomethingStop15 
        
           }; 
        
           #endif    // #if USE_COMPLEX_STRUCT 
        
           ////////////////////////////////////////////////////// 
        
           #define SIMPLE_TIMER_MS        2000L 
        
           // Init SimpleTimer 
        
           SimpleTimer simpleTimer; 
        
           // Here is software Timer, you can do somewhat fancy stuffs without many issues. 
        
           // But always avoid 
        
           // 1. Long delay() it just doing nothing and pain-without-gain wasting CPU power.Plan and design your code / strategy ahead 
        
           // 2. Very long "do", "while", "for" loops without predetermined exit time. 
        
           void simpleTimerDoingSomething2s() 
        
           { 
        
             static unsigned long previousMicrosStart = startMicros; 
        
             unsigned long currMicros = micros(); 
        
             Serial.print(F("SimpleTimer (ms): ")); Serial.print(SIMPLE_TIMER_MS); 
        
             Serial.print(F(", us : ")); Serial.print(currMicros); 
        
             Serial.print(F(", Dus : ")); Serial.println(currMicros - previousMicrosStart); 
        
             for (uint16_t i = 0; i < NUMBER_ISR_PWMS; i++) 
        
             { 
        
           #if USE_COMPLEX_STRUCT 
        
               Serial.print(F("PWM Channel : ")); Serial.print(i); 
        
               Serial.print(F(", programmed Period (us): ")); 
        
             #if USING_PWM_FREQUENCY 
        
               Serial.print(1000000 / curISR_PWM_Data[i].PWM_Freq); 
        
             #else 
        
               Serial.print(curISR_PWM_Data[i].PWM_Period); 
        
             #endif 
        
               Serial.print(F(", actual : ")); Serial.print(curISR_PWM_Data[i].deltaMicrosStart); 
        
               Serial.print(F(", programmed DutyCycle : "));  
        
               Serial.print(curISR_PWM_Data[i].PWM_DutyCycle); 
        
               Serial.print(F(", actual : ")); Serial.println((float) curISR_PWM_Data[i].deltaMicrosStop * 100.0f / curISR_PWM_Data[i].deltaMicrosStart); 
        
           #else 
        
               Serial.print(F("PWM Channel : ")); Serial.print(i); 
        
             #if USING_PWM_FREQUENCY 
        
               Serial.print(1000000 / PWM_Freq[i]); 
        
             #else 
        
               Serial.print(PWM_Period[i]); 
        
             #endif 
        
               Serial.print(F(", programmed Period (us): ")); Serial.print(PWM_Period[i]); 
        
               Serial.print(F(", actual : ")); Serial.print(deltaMicrosStart[i]); 
        
               Serial.print(F(", programmed DutyCycle : "));  
        
               Serial.print(PWM_DutyCycle[i]); 
        
               Serial.print(F(", actual : ")); Serial.println( (float) deltaMicrosStop[i] * 100.0f / deltaMicrosStart[i]); 
        
           #endif 
        
             } 
        
             previousMicrosStart = currMicros; 
        
           } 
        
           void setup() 
        
           { 
        
             Serial.begin(115200); 
        
             while (!Serial); 
        
             delay(2000); 
        
             Serial.print(F("\nStarting ISR_16_PWMs_Array_Complex on ")); Serial.println(BOARD_NAME); 
        
             Serial.println(SAMD_SLOW_PWM_VERSION); 
        
             // 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")); 
        
             startMicros = micros(); 
        
             // 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++) 
        
             { 
        
           #if USE_COMPLEX_STRUCT 
        
               curISR_PWM_Data[i].previousMicrosStart = startMicros; 
        
               //ISR_PWM.setInterval(curISR_PWM_Data[i].PWM_Period, curISR_PWM_Data[i].irqCallbackStartFunc); 
        
               //void setPWM(uint32_t pin, float frequency, float dutycycle 
        
               // , timer_callback_p StartCallback = nullptr, timer_callback_p StopCallback = nullptr) 
        
             #if USING_PWM_FREQUENCY 
        
               // You can use this with PWM_Freq in Hz 
        
               ISR_PWM.setPWM(curISR_PWM_Data[i].PWM_Pin, curISR_PWM_Data[i].PWM_Freq, curISR_PWM_Data[i].PWM_DutyCycle,  
        
                              curISR_PWM_Data[i].irqCallbackStartFunc, curISR_PWM_Data[i].irqCallbackStopFunc); 
        
             #else 
        
               // Or You can use this with PWM_Period in us 
        
               ISR_PWM.setPWM_Period(curISR_PWM_Data[i].PWM_Pin, curISR_PWM_Data[i].PWM_Period, curISR_PWM_Data[i].PWM_DutyCycle,  
        
                                     curISR_PWM_Data[i].irqCallbackStartFunc, curISR_PWM_Data[i].irqCallbackStopFunc); 
        
             #endif 
        
           #else 
        
               previousMicrosStart[i] = micros(); 
        
             #if USING_PWM_FREQUENCY 
        
               // You can use this with PWM_Freq in Hz 
        
               ISR_PWM.setPWM(PWM_Pin[i], PWM_Freq[i], PWM_DutyCycle[i], irqCallbackStartFunc[i], irqCallbackStopFunc[i]); 
        
             #else 
        
               // Or You can use this with PWM_Period in us 
        
               ISR_PWM.setPWM_Period(PWM_Pin[i], PWM_Period[i], PWM_DutyCycle[i], irqCallbackStartFunc[i], irqCallbackStopFunc[i]); 
        
             #endif  
        
           #endif 
        
             } 
        
             // You need this timer for non-critical tasks. Avoid abusing ISR if not absolutely necessary. 
        
             simpleTimer.setInterval(SIMPLE_TIMER_MS, simpleTimerDoingSomething2s); 
        
           } 
        
           #define BLOCKING_TIME_MS      10000L 
        
           void loop() 
        
           { 
        
             // This unadvised blocking task is used to demonstrate the blocking effects onto the execution and accuracy to Software timer 
        
             // You see the time elapse of ISR_PWM still accurate, whereas very unaccurate for Software Timer 
        
             // The time elapse for 2000ms software timer now becomes 3000ms (BLOCKING_TIME_MS) 
        
             // While that of ISR_PWM is still prefect. 
        
             delay(BLOCKING_TIME_MS); 
        
             // You need this Software timer for non-critical tasks. Avoid abusing ISR if not absolutely necessary 
        
             // You don't need to and never call ISR_PWM.run() here in the loop(). It's already handled by ISR timer. 
        
             simpleTimer.run(); 
        
           }

Debug Terminal Output Samples

1. ISR_4_PWMs_Array_Complex on SAMD_NANO_33_IOT

The following is the sample terminal output when running example ISR_16_PWMs_Array_Complex on SAMD_NANO_33_IOT to demonstrate how to use multiple PWM channels with complex callback functions, the accuracy of ISR Hardware PWM-channels, especially when system is very busy. The ISR PWM-channels is running exactly according to corresponding programmed periods and duty-cycles

Starting ISR_4_PWMs_Array_Complex on SAMD_NANO_33_IOT
SAMD_Slow_PWM v1.2.3
Starting ITimer OK, micros() = 2750362
Channel : 0	    Period : 1000000		OnTime : 50000	Start_Time : 2750883
Channel : 1	    Period : 500000		OnTime : 50000	Start_Time : 2751343
Channel : 2	    Period : 250000		OnTime : 50000	Start_Time : 2751845
Channel : 3	    Period : 200000		OnTime : 60000	Start_Time : 2752329
SimpleTimer (ms): 2000, us : 12752801, Dus : 10002150
PWM Channel : 0, programmed Period (us): 1000000.00, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1, programmed Period (us): 500000.00, actual : 499999, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2, programmed Period (us): 250000.00, actual : 249999, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3, programmed Period (us): 200000.00, actual : 199999, programmed DutyCycle : 30.00, actual : 30.00
SimpleTimer (ms): 2000, us : 22757321, Dus : 10004520
PWM Channel : 0, programmed Period (us): 1000000.00, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1, programmed Period (us): 500000.00, actual : 499999, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2, programmed Period (us): 250000.00, actual : 250000, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3, programmed Period (us): 200000.00, actual : 199999, programmed DutyCycle : 30.00, actual : 30.00
SimpleTimer (ms): 2000, us : 32761791, Dus : 10004470
PWM Channel : 0, programmed Period (us): 1000000.00, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1, programmed Period (us): 500000.00, actual : 499999, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2, programmed Period (us): 250000.00, actual : 249999, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3, programmed Period (us): 200000.00, actual : 199999, programmed DutyCycle : 30.00, actual : 30.00
SimpleTimer (ms): 2000, us : 42766231, Dus : 10004440
PWM Channel : 0, programmed Period (us): 1000000.00, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1, programmed Period (us): 500000.00, actual : 499999, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2, programmed Period (us): 250000.00, actual : 249999, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3, programmed Period (us): 200000.00, actual : 199999, programmed DutyCycle : 30.00, actual : 30.00

2. ISR_16_PWMs_Array_Complex on ITSYBITSY_M4

The following is the sample terminal output when running example ISR_16_PWMs_Array_Complex on ITSYBITSY_M4 to demonstrate how to use multiple PWM channels with complex callback functions, the accuracy of ISR Hardware PWM-channels, especially when system is very busy. The ISR PWM-channels is running exactly according to corresponding programmed periods and duty-cycles

Starting ISR_16_PWMs_Array_Complex on ITSYBITSY_M4
SAMD_Slow_PWM v1.2.3
Starting ITimer OK, micros() = 3830244
Channel : 0	    Period : 1000000		OnTime : 50000	Start_Time : 3830538
Channel : 1	    Period : 500000		OnTime : 50000	Start_Time : 3830903
Channel : 2	    Period : 333333		OnTime : 66666	Start_Time : 3831277
Channel : 3	    Period : 250000		OnTime : 75000	Start_Time : 3831708
Channel : 4	    Period : 200000		OnTime : 80000	Start_Time : 3832077
Channel : 5	    Period : 166666		OnTime : 74999	Start_Time : 3832451
Channel : 6	    Period : 142857		OnTime : 71428	Start_Time : 3832874
Channel : 7	    Period : 125000		OnTime : 68750	Start_Time : 3833251
Channel : 8	    Period : 111111		OnTime : 66666	Start_Time : 3833671
Channel : 9	    Period : 100000		OnTime : 65000	Start_Time : 3834049
Channel : 10	    Period : 66666		OnTime : 46666	Start_Time : 3834419
Channel : 11	    Period : 50000		OnTime : 37500	Start_Time : 3834849
Channel : 12	    Period : 40000		OnTime : 32000	Start_Time : 3835219
Channel : 13	    Period : 33333		OnTime : 28333	Start_Time : 3835639
Channel : 14	    Period : 25000		OnTime : 22500	Start_Time : 3836016
Channel : 15	    Period : 20000		OnTime : 19000	Start_Time : 3836393
SimpleTimer (ms): 2000, us : 13836817, Dus : 10006340
PWM Channel : 0, programmed Period (us): 1000000.00, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1, programmed Period (us): 500000.00, actual : 500000, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2, programmed Period (us): 333333.34, actual : 333340, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3, programmed Period (us): 250000.00, actual : 250000, programmed DutyCycle : 30.00, actual : 30.00
PWM Channel : 4, programmed Period (us): 200000.00, actual : 200000, programmed DutyCycle : 40.00, actual : 40.00
PWM Channel : 5, programmed Period (us): 166666.67, actual : 166679, programmed DutyCycle : 45.00, actual : 44.98
PWM Channel : 6, programmed Period (us): 142857.14, actual : 142860, programmed DutyCycle : 50.00, actual : 49.99
PWM Channel : 7, programmed Period (us): 125000.00, actual : 125000, programmed DutyCycle : 55.00, actual : 54.99
PWM Channel : 8, programmed Period (us): 111111.11, actual : 111120, programmed DutyCycle : 60.00, actual : 59.99
PWM Channel : 9, programmed Period (us): 100000.00, actual : 99999, programmed DutyCycle : 65.00, actual : 65.00
PWM Channel : 10, programmed Period (us): 66666.66, actual : 66679, programmed DutyCycle : 70.00, actual : 69.98
PWM Channel : 11, programmed Period (us): 50000.00, actual : 50000, programmed DutyCycle : 75.00, actual : 75.00
PWM Channel : 12, programmed Period (us): 40000.00, actual : 40000, programmed DutyCycle : 80.00, actual : 80.00
PWM Channel : 13, programmed Period (us): 33333.33, actual : 33339, programmed DutyCycle : 85.00, actual : 84.95
PWM Channel : 14, programmed Period (us): 25000.00, actual : 24999, programmed DutyCycle : 90.00, actual : 90.00
PWM Channel : 15, programmed Period (us): 20000.00, actual : 19999, programmed DutyCycle : 95.00, actual : 95.00
SimpleTimer (ms): 2000, us : 23848190, Dus : 10011373
PWM Channel : 0, programmed Period (us): 1000000.00, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1, programmed Period (us): 500000.00, actual : 500000, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2, programmed Period (us): 333333.34, actual : 333340, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3, programmed Period (us): 250000.00, actual : 250000, programmed DutyCycle : 30.00, actual : 30.00
PWM Channel : 4, programmed Period (us): 200000.00, actual : 200000, programmed DutyCycle : 40.00, actual : 40.00
PWM Channel : 5, programmed Period (us): 166666.67, actual : 166679, programmed DutyCycle : 45.00, actual : 44.98
PWM Channel : 6, programmed Period (us): 142857.14, actual : 142860, programmed DutyCycle : 50.00, actual : 49.99
PWM Channel : 7, programmed Period (us): 125000.00, actual : 125000, programmed DutyCycle : 55.00, actual : 54.99
PWM Channel : 8, programmed Period (us): 111111.11, actual : 111120, programmed DutyCycle : 60.00, actual : 59.99
PWM Channel : 9, programmed Period (us): 100000.00, actual : 99999, programmed DutyCycle : 65.00, actual : 65.00
PWM Channel : 10, programmed Period (us): 66666.66, actual : 66679, programmed DutyCycle : 70.00, actual : 69.98
PWM Channel : 11, programmed Period (us): 50000.00, actual : 50000, programmed DutyCycle : 75.00, actual : 75.00
PWM Channel : 12, programmed Period (us): 40000.00, actual : 40000, programmed DutyCycle : 80.00, actual : 80.00
PWM Channel : 13, programmed Period (us): 33333.33, actual : 33339, programmed DutyCycle : 85.00, actual : 84.94
PWM Channel : 14, programmed Period (us): 25000.00, actual : 24999, programmed DutyCycle : 90.00, actual : 90.01
PWM Channel : 15, programmed Period (us): 20000.00, actual : 20000, programmed DutyCycle : 95.00, actual : 95.00

3. ISR_4_PWMs_Array_Complex on SEEED_XIAO_M0

The following is the sample terminal output when running example ISR_4_PWMs_Array_Complex on SEEED_XIAO_M0 to demonstrate how to use multiple PWM channels with complex callback functions, the accuracy of ISR Hardware PWM-channels, especially when system is very busy. The ISR PWM-channels is running exactly according to corresponding programmed periods and duty-cycles

Starting ISR_16_PWMs_Array_Complex on SEEED_XIAO_M0
SAMD_Slow_PWM v1.2.3
Starting ITimer OK, micros() = 2681651
Channel : 0	Period : 1000000		OnTime : 50000	Start_Time : 2682003
Channel : 1	Period : 500000		OnTime : 50000	Start_Time : 2682003
Channel : 2	Period : 66666		OnTime : 13333	Start_Time : 2682003
Channel : 3	Period : 50000		OnTime : 15000	Start_Time : 2682003
SimpleTimer (ms): 2000, us : 22699166, Dus : 10011622
PWM Channel : 0, programmed Period (us): 1000000, actual : 1000000, programmed DutyCycle : 5, actual : 5.00
PWM Channel : 1, programmed Period (us): 500000, actual : 500009, programmed DutyCycle : 10, actual : 10.00
PWM Channel : 2, programmed Period (us): 66666, actual : 66679, programmed DutyCycle : 20, actual : 19.98
PWM Channel : 3, programmed Period (us): 50000, actual : 50005, programmed DutyCycle : 30, actual : 29.99
SimpleTimer (ms): 2000, us : 32713108, Dus : 10013942
PWM Channel : 0, programmed Period (us): 1000000, actual : 1000000, programmed DutyCycle : 5, actual : 5.00
PWM Channel : 1, programmed Period (us): 500000, actual : 499999, programmed DutyCycle : 10, actual : 10.00
PWM Channel : 2, programmed Period (us): 66666, actual : 66679, programmed DutyCycle : 20, actual : 19.98
PWM Channel : 3, programmed Period (us): 50000, actual : 49999, programmed DutyCycle : 30, actual : 30.00

4. ISR_Modify_PWM on SAMD_NANO_33_IOT

The following is the sample terminal output when running example ISR_Modify_PWM on SAMD_NANO_33_IOT to demonstrate how to modify PWM settings on-the-fly without deleting the PWM channel

Starting ISR_Modify_PWM on SAMD_NANO_33_IOT
SAMD_Slow_PWM v1.2.3
[PWM] SAMDTimerInterrupt: F_CPU (MHz) = 48 , TIMER_HZ = 48
[PWM] TC3_Timer::startTimer _Timer = 0x 42002c00 , TC3 = 0x 42002c00
Starting ITimer OK, micros() = 3761339
Using PWM Freq = 200.00, PWM DutyCycle = 1.00
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 3762307
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 13762340
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 23757340
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 33762390
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 43757390
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 53762390
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 63767390
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 73767390
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 83762390
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 93767390
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 103762390
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 113772440
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 123767440

5. ISR_Changing_PWM on SAMD_NANO_33_IOT

The following is the sample terminal output when running example ISR_Changing_PWM on SAMD_NANO_33_IOT to demonstrate how to modify PWM settings on-the-fly by deleting the PWM channel and reinit the PWM channel

Starting ISR_Changing_PWM on SAMD_NANO_33_IOT
SAMD_Slow_PWM v1.2.3
Starting ITimer OK, micros() = 2820370
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 2821335
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 12822309
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 22823296
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 32824232
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 42825239
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 52826230
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 62827189

6. ISR_Modify_PWM on ITSYBITSY_M4

The following is the sample terminal output when running example ISR_Modify_PWM on ITSYBITSY_M4 to demonstrate how to modify PWM settings on-the-fly without deleting the PWM channel

Starting ISR_Modify_PWM on ITSYBITSY_M4
SAMD_Slow_PWM v1.2.3
Starting ITimer OK, micros() = 3320212
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 3320837
Channel : 0	New Period : 500000		OnTime : 450000	Start_Time : 13320852
Channel : 0	New Period : 1000000		OnTime : 500000	Start_Time : 23320852
Channel : 0	New Period : 500000		OnTime : 450000	Start_Time : 32820852
Channel : 0	New Period : 1000000		OnTime : 500000	Start_Time : 43320852
Channel : 0	New Period : 500000		OnTime : 450000	Start_Time : 52820852
Channel : 0	New Period : 1000000		OnTime : 500000	Start_Time : 63320852
Channel : 0	New Period : 500000		OnTime : 450000	Start_Time : 72820852
Channel : 0	New Period : 1000000		OnTime : 500000	Start_Time : 83320852
Channel : 0	New Period : 500000		OnTime : 450000	Start_Time : 92820852
Channel : 0	New Period : 1000000		OnTime : 500000	Start_Time : 103320852
Channel : 0	New Period : 500000		OnTime : 450000	Start_Time : 112820852
Channel : 0	New Period : 1000000		OnTime : 500000	Start_Time : 123320852
Channel : 0	New Period : 500000		OnTime : 450000	Start_Time : 132820852
Channel : 0	New Period : 1000000		OnTime : 500000	Start_Time : 143320852
Channel : 0	New Period : 500000		OnTime : 450000	Start_Time : 152820852
Channel : 0	New Period : 1000000		OnTime : 500000	Start_Time : 163320852
Channel : 0	New Period : 500000		OnTime : 450000	Start_Time : 172820852

7. ISR_Changing_PWM on ITSYBITSY_M4

The following is the sample terminal output when running example ISR_Changing_PWM on ITSYBITSY_M4 to demonstrate how to modify PWM settings on-the-fly by deleting the PWM channel and reinit the PWM channel

Starting ISR_Changing_PWM on ITSYBITSY_M4
SAMD_Slow_PWM v1.2.3
Starting ITimer OK, micros() = 3660252
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 3660870
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 13661504
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 23662239

Debug

Debug is enabled by default on Serial.

You can also change the debugging level _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_     0

Troubleshooting

If you get compilation errors, more often than not, you may need to install a newer version of the core for Arduino boards.

Sometimes, the library will only work if you update the board core to the latest version because I am using newly added functions.

Issues

Submit issues to: SAMD_Slow_PWM issues

TO DO

Search for bug and improvement.
Similar features for remaining Arduino boards

DONE

Basic hardware multi-channel PWM for SAMD21/SAMD51 boards such as NANO_33_IOT, ITSYBITSY_M4, SEEED_XIAO_M0, SparkFun_SAMD51_Thing_Plus, etc. using Arduino, Adafruit or Sparkfun core
Add Table of Contents
Add functions to modify PWM settings on-the-fly
Fix multiple-definitions linker error. Drop src_cpp and src_h directories
DutyCycle to be optionally updated at the end current PWM period instead of immediately.
Add examples SAMD21 multiFileProject and SAMD51 multiFileProjectto demo for multiple-file project
Improve accuracy by using float, instead of uint32_t for dutycycle
Optimize library code by using reference-passing instead of value-passing
Add support to many more boards, such as SAMD21E1xA, SAMD21G1xA andSAMD21J1xA
Display informational warning only when _PWM_LOGLEVEL_ > 3

Contributions and Thanks

Many thanks for everyone for bug reporting, new feature suggesting, testing and contributing to the development of this library.

toniMephis to report

issue missing header #2 leading to version v1.2.2
issues float precisison of DutyCycle only sometimes working #3 and random dropouts #4 leading to version v1.2.3

_{⭐️ toniMephis}

Contributing

If you want to contribute to this project:

Report bugs and errors
Ask for enhancements
Create issues and pull requests
Tell other people about this library

License

The library is licensed under MIT

Name		Name	Last commit message	Last commit date
Latest commit History 44 Commits
.github		.github
Packages_Patches		Packages_Patches
examples		examples
platformio		platformio
src		src
utils		utils
.codespellrc		.codespellrc
.gitignore		.gitignore
CONTRIBUTING.md		CONTRIBUTING.md
LICENSE		LICENSE
README.md		README.md
changelog.md		changelog.md
keywords.txt		keywords.txt
library.json		library.json
library.properties		library.properties

	#if !( defined(__SAMD51__) \|\| defined(__SAMD51J20A__) \|\| defined(__SAMD51J19A__) \|\| defined(__SAMD51G19A__) \|\| defined(__SAMD51P19A__) )
	#error This code is designed to run on SAMD51 platform! Please check your Tools->Board setting.
	#endif

	// These define's must be placed at the beginning before #include "ESP32_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

	#define MAX_SAMD_PWM_FREQ 1000

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

	#define boolean bool

	#include <SimpleTimer.h> // https://github.com/jfturcot/SimpleTimer

	#define LED_OFF LOW
	#define LED_ON HIGH

	#ifndef LED_BUILTIN
	#define LED_BUILTIN 13
	#endif

	#ifndef LED_BLUE
	#define LED_BLUE 2
	#endif

	#ifndef LED_RED
	#define LED_RED 3
	#endif

	#define HW_TIMER_INTERVAL_US 20L

	uint64_t startMicros = 0;

	// You can only select SAMD51 Hardware Timer TC3
	// Init SAMD timer TIMER_TC3
	SAMDTimer ITimer(TIMER_TC3);

	// Init SAMD_Slow_PWM
	SAMD_Slow_PWM ISR_PWM;


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

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

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

	#define NUMBER_ISR_PWMS 16

	#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
	#define PIN_D7 7
	#define PIN_D8 8
	#define PIN_D9 9
	#define PIN_D10 10
	#define PIN_D11 11
	#define PIN_D12 12

	typedef void (*irqCallback) ();

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

	#define USE_COMPLEX_STRUCT true

	#define USING_PWM_FREQUENCY true

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

	#if USE_COMPLEX_STRUCT

	typedef struct
	{
	uint32_t PWM_Pin;
	irqCallback irqCallbackStartFunc;
	irqCallback irqCallbackStopFunc;

	#if USING_PWM_FREQUENCY
	float PWM_Freq;
	#else
	uint32_t PWM_Period;
	#endif

	float PWM_DutyCycle;

	uint64_t deltaMicrosStart;
	uint64_t previousMicrosStart;

	uint64_t deltaMicrosStop;
	uint64_t previousMicrosStop;

	} ISR_PWM_Data;

	// In NRF52, avoid doing something fancy in ISR, for example Serial.print()
	// 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 doingSomethingStart(int index);

	void doingSomethingStop(int index);

	#else // #if USE_COMPLEX_STRUCT

	volatile unsigned long deltaMicrosStart [] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
	volatile unsigned long previousMicrosStart [] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

	volatile unsigned long deltaMicrosStop [] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
	volatile unsigned long previousMicrosStop [] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

	// You can assign pins here. Be carefull to select good pin to use or crash, e.g pin 6-11
	uint32_t PWM_Pin[] =
	{
	LED_BUILTIN, LED_BLUE, LED_RED, PIN_D0, PIN_D1, PIN_D2, PIN_D3, PIN_D4,
	PIN_D5, PIN_D6, PIN_D7, PIN_D8, PIN_D9, PIN_D10, PIN_D11, PIN_D12
	};

	// You can assign any interval for any timer here, in microseconds
	uint32_t PWM_Period[] =
	{
	10000000, 5000000, 333333, 250000, 200000, 166667, 142857, 125000,
	111111, 100000, 66667, 50000, 40000, 33333, 25000, 20000
	};

	// 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,
	9.0f, 10.0f, 15.0f, 20.0f, 25.0f, 30.0f, 40.0f, 50.0f
	};

	// You can assign any interval for any timer here, in milliseconds
	float PWM_DutyCycle[] =
	{
	5.00, 10.00, 20.00, 30.00, 40.00, 45.00, 50.00, 55.00,
	60.00, 65.00, 70.00, 75.00, 80.00, 85.00, 90.00, 95.00
	};

	void doingSomethingStart(int index)
	{
	unsigned long currentMicros = micros();

	deltaMicrosStart[index] = currentMicros - previousMicrosStart[index];
	previousMicrosStart[index] = currentMicros;
	}

	void doingSomethingStop(int index)
	{
	unsigned long currentMicros = micros();

	// Count from start to stop PWM pulse
	deltaMicrosStop[index] = currentMicros - previousMicrosStart[index];
	previousMicrosStop[index] = currentMicros;
	}

	#endif // #if USE_COMPLEX_STRUCT

	////////////////////////////////////
	// Shared
	////////////////////////////////////

	void doingSomethingStart0()
	{
	doingSomethingStart(0);
	}

	void doingSomethingStart1()
	{
	doingSomethingStart(1);
	}

	void doingSomethingStart2()
	{
	doingSomethingStart(2);
	}

	void doingSomethingStart3()
	{
	doingSomethingStart(3);
	}

	void doingSomethingStart4()
	{
	doingSomethingStart(4);
	}

	void doingSomethingStart5()
	{
	doingSomethingStart(5);
	}

	void doingSomethingStart6()
	{
	doingSomethingStart(6);
	}

	void doingSomethingStart7()
	{
	doingSomethingStart(7);
	}

	void doingSomethingStart8()
	{
	doingSomethingStart(8);
	}

	void doingSomethingStart9()
	{
	doingSomethingStart(9);
	}

	void doingSomethingStart10()
	{
	doingSomethingStart(10);
	}

	void doingSomethingStart11()
	{
	doingSomethingStart(11);
	}

	void doingSomethingStart12()
	{
	doingSomethingStart(12);
	}

	void doingSomethingStart13()
	{
	doingSomethingStart(13);
	}

	void doingSomethingStart14()
	{
	doingSomethingStart(14);
	}

	void doingSomethingStart15()
	{
	doingSomethingStart(15);
	}

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

	void doingSomethingStop0()
	{
	doingSomethingStop(0);
	}

	void doingSomethingStop1()
	{
	doingSomethingStop(1);
	}

	void doingSomethingStop2()
	{
	doingSomethingStop(2);
	}

	void doingSomethingStop3()
	{
	doingSomethingStop(3);
	}

	void doingSomethingStop4()
	{
	doingSomethingStop(4);
	}

	void doingSomethingStop5()
	{
	doingSomethingStop(5);
	}

	void doingSomethingStop6()
	{
	doingSomethingStop(6);
	}

	void doingSomethingStop7()
	{
	doingSomethingStop(7);
	}

	void doingSomethingStop8()
	{
	doingSomethingStop(8);
	}

	void doingSomethingStop9()
	{
	doingSomethingStop(9);
	}

	void doingSomethingStop10()
	{
	doingSomethingStop(10);
	}

	void doingSomethingStop11()
	{
	doingSomethingStop(11);
	}

	void doingSomethingStop12()
	{
	doingSomethingStop(12);
	}

	void doingSomethingStop13()
	{
	doingSomethingStop(13);
	}

	void doingSomethingStop14()
	{
	doingSomethingStop(14);
	}

	void doingSomethingStop15()
	{
	doingSomethingStop(15);
	}

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

	#if USE_COMPLEX_STRUCT

	#if USING_PWM_FREQUENCY

	ISR_PWM_Data curISR_PWM_Data[] =
	{
	// pin, irqCallbackStartFunc, irqCallbackStopFunc, PWM_Freq, PWM_DutyCycle, deltaMicrosStart, previousMicrosStart, deltaMicrosStop, previousMicrosStop
	{ LED_BUILTIN, doingSomethingStart0, doingSomethingStop0, 1.0, 5.0, 0, 0, 0, 0 },
	{ LED_BLUE, doingSomethingStart1, doingSomethingStop1, 2.0, 10.0, 0, 0, 0, 0 },
	{ LED_RED, doingSomethingStart2, doingSomethingStop2, 3.0, 20.0, 0, 0, 0, 0 },
	{ PIN_D0, doingSomethingStart3, doingSomethingStop3, 4.0, 30.0, 0, 0, 0, 0 },
	{ PIN_D1, doingSomethingStart4, doingSomethingStop4, 5.0, 40.0, 0, 0, 0, 0 },
	{ PIN_D2, doingSomethingStart5, doingSomethingStop5, 6.0, 45.0, 0, 0, 0, 0 },
	{ PIN_D3, doingSomethingStart6, doingSomethingStop6, 7.0, 50.0, 0, 0, 0, 0 },
	{ PIN_D4, doingSomethingStart7, doingSomethingStop7, 8.0, 55.0, 0, 0, 0, 0 },
	{ PIN_D5, doingSomethingStart8, doingSomethingStop8, 9.0, 60.0, 0, 0, 0, 0 },
	{ PIN_D6, doingSomethingStart9, doingSomethingStop9, 10.0, 65.0, 0, 0, 0, 0 },
	{ PIN_D7, doingSomethingStart10, doingSomethingStop10, 15.0, 70.0, 0, 0, 0, 0 },
	{ PIN_D8, doingSomethingStart11, doingSomethingStop11, 20.0, 75.0, 0, 0, 0, 0 },
	{ PIN_D9, doingSomethingStart12, doingSomethingStop12, 25.0, 80.0, 0, 0, 0, 0 },
	{ PIN_D10, doingSomethingStart13, doingSomethingStop13, 30.0, 85.0, 0, 0, 0, 0 },
	{ PIN_D11, doingSomethingStart14, doingSomethingStop14, 40.0, 90.0, 0, 0, 0, 0 },
	{ PIN_D12, doingSomethingStart15, doingSomethingStop15, 50.0, 95.0, 0, 0, 0, 0 }
	};

	#else // #if USING_PWM_FREQUENCY

	ISR_PWM_Data curISR_PWM_Data[] =
	{
	// pin, irqCallbackStartFunc, irqCallbackStopFunc, PWM_Period, PWM_DutyCycle, deltaMicrosStart, previousMicrosStart, deltaMicrosStop, previousMicrosStop
	{ LED_BUILTIN, doingSomethingStart0, doingSomethingStop0, 1000000, 5.0, 0, 0, 0, 0 },
	{ LED_BLUE, doingSomethingStart1, doingSomethingStop1, 500000, 10.0, 0, 0, 0, 0 },
	{ LED_RED, doingSomethingStart2, doingSomethingStop2, 333333, 20.0, 0, 0, 0, 0 },
	{ PIN_D0, doingSomethingStart3, doingSomethingStop3, 250000, 30.0, 0, 0, 0, 0 },
	{ PIN_D1, doingSomethingStart4, doingSomethingStop4, 200000, 40.0, 0, 0, 0, 0 },
	{ PIN_D2, doingSomethingStart5, doingSomethingStop5, 166667, 45.0, 0, 0, 0, 0 },
	{ PIN_D3, doingSomethingStart6, doingSomethingStop6, 142857, 50.0, 0, 0, 0, 0 },
	{ PIN_D4, doingSomethingStart7, doingSomethingStop7, 125000, 55.0, 0, 0, 0, 0 },
	{ PIN_D5, doingSomethingStart8, doingSomethingStop8, 111111, 60.0, 0, 0, 0, 0 },
	{ PIN_D6, doingSomethingStart9, doingSomethingStop9, 100000, 65.0, 0, 0, 0, 0 },
	{ PIN_D7, doingSomethingStart10, doingSomethingStop10, 66667, 70.0, 0, 0, 0, 0 },
	{ PIN_D8, doingSomethingStart11, doingSomethingStop11, 50000, 75.0, 0, 0, 0, 0 },
	{ PIN_D9, doingSomethingStart12, doingSomethingStop12, 40000, 80.0, 0, 0, 0, 0 },
	{ PIN_D10, doingSomethingStart13, doingSomethingStop13, 33333, 85.0, 0, 0, 0, 0 },
	{ PIN_D11, doingSomethingStart14, doingSomethingStop14, 25000, 90.0, 0, 0, 0, 0 },
	{ PIN_D12, doingSomethingStart15, doingSomethingStop15, 20000, 95.0, 0, 0, 0, 0 }
	};

	#endif // #if USING_PWM_FREQUENCY

	void doingSomethingStart(int index)
	{
	unsigned long currentMicros = micros();

	curISR_PWM_Data[index].deltaMicrosStart = currentMicros - curISR_PWM_Data[index].previousMicrosStart;
	curISR_PWM_Data[index].previousMicrosStart = currentMicros;
	}

	void doingSomethingStop(int index)
	{
	unsigned long currentMicros = micros();

	//curISR_PWM_Data[index].deltaMicrosStop = currentMicros - curISR_PWM_Data[index].previousMicrosStop;
	// Count from start to stop PWM pulse
	curISR_PWM_Data[index].deltaMicrosStop = currentMicros - curISR_PWM_Data[index].previousMicrosStart;
	curISR_PWM_Data[index].previousMicrosStop = currentMicros;
	}

	#else // #if USE_COMPLEX_STRUCT

	irqCallback irqCallbackStartFunc[] =
	{
	doingSomethingStart0, doingSomethingStart1, doingSomethingStart2, doingSomethingStart3,
	doingSomethingStart4, doingSomethingStart5, doingSomethingStart6, doingSomethingStart7,
	doingSomethingStart8, doingSomethingStart9, doingSomethingStart10, doingSomethingStart11,
	doingSomethingStart12, doingSomethingStart13, doingSomethingStart14, doingSomethingStart15
	};

	irqCallback irqCallbackStopFunc[] =
	{
	doingSomethingStop0, doingSomethingStop1, doingSomethingStop2, doingSomethingStop3,
	doingSomethingStop4, doingSomethingStop5, doingSomethingStop6, doingSomethingStop7,
	doingSomethingStop8, doingSomethingStop9, doingSomethingStop10, doingSomethingStop11,
	doingSomethingStop12, doingSomethingStop13, doingSomethingStop14, doingSomethingStop15
	};

	#endif // #if USE_COMPLEX_STRUCT

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

	#define SIMPLE_TIMER_MS 2000L

	// Init SimpleTimer
	SimpleTimer simpleTimer;

	// Here is software Timer, you can do somewhat fancy stuffs without many issues.
	// But always avoid
	// 1. Long delay() it just doing nothing and pain-without-gain wasting CPU power.Plan and design your code / strategy ahead
	// 2. Very long "do", "while", "for" loops without predetermined exit time.
	void simpleTimerDoingSomething2s()
	{
	static unsigned long previousMicrosStart = startMicros;

	unsigned long currMicros = micros();

	Serial.print(F("SimpleTimer (ms): ")); Serial.print(SIMPLE_TIMER_MS);
	Serial.print(F(", us : ")); Serial.print(currMicros);
	Serial.print(F(", Dus : ")); Serial.println(currMicros - previousMicrosStart);

	for (uint16_t i = 0; i < NUMBER_ISR_PWMS; i++)
	{
	#if USE_COMPLEX_STRUCT
	Serial.print(F("PWM Channel : ")); Serial.print(i);
	Serial.print(F(", programmed Period (us): "));

	#if USING_PWM_FREQUENCY
	Serial.print(1000000 / curISR_PWM_Data[i].PWM_Freq);
	#else
	Serial.print(curISR_PWM_Data[i].PWM_Period);
	#endif

	Serial.print(F(", actual : ")); Serial.print(curISR_PWM_Data[i].deltaMicrosStart);

	Serial.print(F(", programmed DutyCycle : "));

	Serial.print(curISR_PWM_Data[i].PWM_DutyCycle);

	Serial.print(F(", actual : ")); Serial.println((float) curISR_PWM_Data[i].deltaMicrosStop * 100.0f / curISR_PWM_Data[i].deltaMicrosStart);

	#else

	Serial.print(F("PWM Channel : ")); Serial.print(i);

	#if USING_PWM_FREQUENCY
	Serial.print(1000000 / PWM_Freq[i]);
	#else
	Serial.print(PWM_Period[i]);
	#endif

	Serial.print(F(", programmed Period (us): ")); Serial.print(PWM_Period[i]);
	Serial.print(F(", actual : ")); Serial.print(deltaMicrosStart[i]);

	Serial.print(F(", programmed DutyCycle : "));

	Serial.print(PWM_DutyCycle[i]);

	Serial.print(F(", actual : ")); Serial.println( (float) deltaMicrosStop[i] * 100.0f / deltaMicrosStart[i]);
	#endif
	}

	previousMicrosStart = currMicros;
	}

	void setup()
	{
	Serial.begin(115200);
	while (!Serial);

	delay(2000);

	Serial.print(F("\nStarting ISR_16_PWMs_Array_Complex on ")); Serial.println(BOARD_NAME);
	Serial.println(SAMD_SLOW_PWM_VERSION);

	// 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"));

	startMicros = micros();

	// 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++)
	{
	#if USE_COMPLEX_STRUCT
	curISR_PWM_Data[i].previousMicrosStart = startMicros;
	//ISR_PWM.setInterval(curISR_PWM_Data[i].PWM_Period, curISR_PWM_Data[i].irqCallbackStartFunc);

	//void setPWM(uint32_t pin, float frequency, float dutycycle
	// , timer_callback_p StartCallback = nullptr, timer_callback_p StopCallback = nullptr)

	#if USING_PWM_FREQUENCY
	// You can use this with PWM_Freq in Hz
	ISR_PWM.setPWM(curISR_PWM_Data[i].PWM_Pin, curISR_PWM_Data[i].PWM_Freq, curISR_PWM_Data[i].PWM_DutyCycle,
	curISR_PWM_Data[i].irqCallbackStartFunc, curISR_PWM_Data[i].irqCallbackStopFunc);
	#else
	// Or You can use this with PWM_Period in us
	ISR_PWM.setPWM_Period(curISR_PWM_Data[i].PWM_Pin, curISR_PWM_Data[i].PWM_Period, curISR_PWM_Data[i].PWM_DutyCycle,
	curISR_PWM_Data[i].irqCallbackStartFunc, curISR_PWM_Data[i].irqCallbackStopFunc);
	#endif

	#else
	previousMicrosStart[i] = micros();

	#if USING_PWM_FREQUENCY
	// You can use this with PWM_Freq in Hz
	ISR_PWM.setPWM(PWM_Pin[i], PWM_Freq[i], PWM_DutyCycle[i], irqCallbackStartFunc[i], irqCallbackStopFunc[i]);
	#else
	// Or You can use this with PWM_Period in us
	ISR_PWM.setPWM_Period(PWM_Pin[i], PWM_Period[i], PWM_DutyCycle[i], irqCallbackStartFunc[i], irqCallbackStopFunc[i]);
	#endif

	#endif
	}

	// You need this timer for non-critical tasks. Avoid abusing ISR if not absolutely necessary.
	simpleTimer.setInterval(SIMPLE_TIMER_MS, simpleTimerDoingSomething2s);
	}

	#define BLOCKING_TIME_MS 10000L

	void loop()
	{
	// This unadvised blocking task is used to demonstrate the blocking effects onto the execution and accuracy to Software timer
	// You see the time elapse of ISR_PWM still accurate, whereas very unaccurate for Software Timer
	// The time elapse for 2000ms software timer now becomes 3000ms (BLOCKING_TIME_MS)
	// While that of ISR_PWM is still prefect.
	delay(BLOCKING_TIME_MS);

	// You need this Software timer for non-critical tasks. Avoid abusing ISR if not absolutely necessary
	// You don't need to and never call ISR_PWM.run() here in the loop(). It's already handled by ISR timer.
	simpleTimer.run();
	}

License

khoih-prog/SAMD_Slow_PWM

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SAMD_Slow_PWM Library

Table of Contents

Important Change from v1.2.0

Why do we need this SAMD_Slow_PWM library

Features

Why using ISR-based PWM is better

Currently supported Boards

Important Notes about ISR

Prerequisites

Installation

Use Arduino Library Manager

Manual Install

VS Code & PlatformIO

Packages' Patches

1. For Arduino SAMD boards

For core version v1.8.10+

For core version v1.8.9-

2. For Adafruit SAMD boards

3. For Seeeduino SAMD boards

4. For SparkFun SAMD boards

HOWTO Fix Multiple Definitions Linker Error

Usage

1. Init Hardware Timer

2. Set PWM Frequency, dutycycle, attach irqCallbackStartFunc and irqCallbackStopFunc functions

Examples:

For SAMD21

For SAMD51

Example SAMD51 ISR_16_PWMs_Array_Complex

Debug Terminal Output Samples

1. ISR_4_PWMs_Array_Complex on SAMD_NANO_33_IOT

2. ISR_16_PWMs_Array_Complex on ITSYBITSY_M4

3. ISR_4_PWMs_Array_Complex on SEEED_XIAO_M0

4. ISR_Modify_PWM on SAMD_NANO_33_IOT

5. ISR_Changing_PWM on SAMD_NANO_33_IOT

6. ISR_Modify_PWM on ITSYBITSY_M4

7. ISR_Changing_PWM on ITSYBITSY_M4

Debug

Troubleshooting

Issues

TO DO

DONE

Contributions and Thanks

Contributing

License

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HOWTO Fix `Multiple Definitions` Linker Error

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