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Published 20 hours ago • verified publisher icon khoih-prog
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This library enables you to use Interrupt from Hardware Timers on an ESP32, ESP32_S2 or ESP32_C3-based board to create and output PWM to pins. It now supports 16 ISR-based synchronized PWM channels, w...

ESP32_PWM Library

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Table of Contents

  • Important Change from v1.2.0
  • Why do we need this ESP32_PWM library
    • Why using ISR-based PWM-channels is better
    • Currently supported Boards
    • Important Notes about ISR
  • Changelog
  • Prerequisites
  • Installation
    • Use Arduino Library Manager
    • Manual Install
    • VS Code & PlatformIO
  • HOWTO Fix Multiple Definitions Linker Error
  • HOWTO Use analogRead() with ESP32 running WiFi and/or BlueTooth (BT/BLE)
    • 1. ESP32 has 2 ADCs, named ADC1 and ADC2
    • 2. ESP32 ADCs functions
    • 3. ESP32 WiFi uses ADC2 for WiFi functions
  • More useful Information
  • How to use
  • Examples
    • 1. ISR_16_PWMs_Array
    • 2. ISR_16_PWMs_Array_Complex
    • 3. ISR_16_PWMs_Array_Simple
    • 4. ISR_Changing_PWM
    • 5. ISR_Modify_PWM
    • 6. multiFileProject New
  • Example ISR_16_PWMs_Array_Complex
  • Debug Terminal Output Samples
    • 1. ISR_16_PWMs_Array_Complex on ESP32_DEV
    • 2. ISR_16_PWMs_Array on ESP32_DEV
    • 3. ISR_16_PWMs_Array_Simple on ESP32_DEV
    • 4. ISR_Modify_PWM on ESP32_DEV
    • 5. ISR_Changing_PWM on ESP32_DEV
    • 6. ISR_Modify_PWM on ESP32S2_DEV
    • 7. ISR_Changing_PWM on ESP32S2_DEV
    • 8. ISR_Modify_PWM on ESP32C3_DEV
    • 9. ISR_Changing_PWM on ESP32C3_DEV
    • 10. ISR_16_PWMs_Array_Complex on ESP32S3_DEV New
  • 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 is possibly some crash depending on use-case.

You can modify to use larger HW_TIMER_INTERVAL_US, (from current 20uS), according to your board and use-case if crash happens.

// Current 20uS
#define HW_TIMER_INTERVAL_US      20L

Why do we need this ESP32_PWM library

Features

This library enables you to use Interrupt from Hardware Timers on an ESP32, ESP32_S2-based board to create and output PWM to pins. Becayse this library doesn't use the powerful hardware-controlled PWM with limitations, the maximum PWM frequency is currently limited at 500Hz, which is suitable for many real-life applications. Now you can also modify PWM settings on-the-fly.

This library enables you to use Interrupt from Hardware Timers on an ESP32, ESP32_S2 or ESP32_C3-based board 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 timers 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 timers, 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 ISR_16_PWMs_Array_Complex example will demonstrate the nearly perfect accuracy compared to software timers by printing the actual elapsed millisecs of each type of PWM channels.

Being ISR-based timers, their executions are not blocked by bad-behaving functions / tasks, such as connecting to WiFi, Internet and 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.

Why using ISR-based PWM-channels 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 PWM-channels 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

  1. ESP32 boards, such as ESP32_DEV, etc.
  2. ESP32_S2-based boards, such as ESP32S2_DEV, ESP32_S2 Saola, Adafruit QTPY_ESP32S2, ESP32S2 Native USB, UM FeatherS2 Neo, UM TinyS2, UM RMP, microS2, etc.
  3. ESP32_C3-based boards, such as ESP32C3_DEV, LOLIN_C3_MINI, DFROBOT_BEETLE_ESP32_C3, ADAFRUIT_QTPY_ESP32C3, AirM2M_CORE_ESP32C3, XIAO_ESP32C3, etc. New
  4. ESP32_S3-based boards, such as ESP32S3_DEV, ESP32_S3_BOX, UM TINYS3, UM PROS3, UM FEATHERS3, FEATHER_ESP32S3_NOPSRAM, QTPY_ESP32S3_NOPSRAM, etc. New

Important Notes about ISR

  1. 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.

  2. 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

  1. Arduino IDE 1.8.19+ for Arduino. GitHub release
  2. ESP32 Core 2.0.5+ for ESP32-based boards. Latest release.
  3. 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 ESP32_PWM, then select / install the latest version. You can also use this link arduino-library-badge for more detailed instructions.

Manual Install

Another way to install is to:

  1. Navigate to ESP32_PWM page.
  2. Download the latest release ESP32_PWM-main.zip.
  3. Extract the zip file to ESP32_PWM-main directory
  4. Copy whole ESP32_PWM-main folder to Arduino libraries' directory such as ~/Arduino/libraries/.

VS Code & PlatformIO

  1. Install VS Code
  2. Install PlatformIO
  3. Install ESP32_PWM library by using Library Manager. Search for ESP32_PWM in Platform.io Author's Libraries
  4. 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

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 "ESP32_PWM.hpp"     //https://github.com/khoih-prog/ESP32_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 "ESP32_PWM.h"           //https://github.com/khoih-prog/ESP32_PWM

Check the new multiFileProject example for a HOWTO demo.

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

HOWTO Use analogRead() with ESP32 running WiFi and/or BlueTooth (BT/BLE)

Please have a look at ESP_WiFiManager Issue 39: Not able to read analog port when using the autoconnect example to have more detailed description and solution of the issue.

1. ESP32 has 2 ADCs, named ADC1 and ADC2

2. ESP32 ADCs functions

  • ADC1 controls ADC function for pins GPIO32-GPIO39
  • ADC2 controls ADC function for pins GPIO0, 2, 4, 12-15, 25-27

3.. ESP32 WiFi uses ADC2 for WiFi functions

Look in file adc_common.c

In ADC2, there're two locks used for different cases:

  1. lock shared with app and Wi-Fi: ESP32: When Wi-Fi using the ADC2, we assume it will never stop, so app checks the lock and returns immediately if failed. ESP32S2: The controller's control over the ADC is determined by the arbiter. There is no need to control by lock.

  2. lock shared between tasks: when several tasks sharing the ADC2, we want to guarantee all the requests will be handled. Since conversions are short (about 31us), app returns the lock very soon, we use a spinlock to stand there waiting to do conversions one by one.

adc2_spinlock should be acquired first, then adc2_wifi_lock or rtc_spinlock.

  • In order to use ADC2 for other functions, we have to acquire complicated firmware locks and very difficult to do
  • So, it's not advisable to use ADC2 with WiFi/BlueTooth (BT/BLE).
  • Use ADC1, and pins GPIO32-GPIO39
  • If somehow it's a must to use those pins serviced by ADC2 (GPIO0, 2, 4, 12, 13, 14, 15, 25, 26 and 27), use the fix mentioned at the end of ESP_WiFiManager Issue 39: Not able to read analog port when using the autoconnect example to work with ESP32 WiFi/BlueTooth (BT/BLE).

More useful Information

ESP32 Hardware Timers

  • The ESP32, ESP32_S2 and ESP32_S3 has two timer groups, each one with two general purpose hardware timers.
  • The ESP32_C3 has two timer groups, each one with only one general purpose hardware timer.
  • All the timers are based on 64-bit counters (except 54-bit counter for ESP32_S3 counter) and 16-bit prescalers.
  • The timer counters can be configured to count up or down and support automatic reload and software reload.
  • They can also generate alarms when they reach a specific value, defined by the software.
  • The value of the counter can be read by the software program.

Now with these new 16 ISR-based PWM-channels (while consuming only 1 hardware timer), the maximum interval is practically unlimited (limited only by unsigned long milliseconds). The accuracy is nearly perfect compared to software PWM-channels. 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 ISR_16_PWMs_Array_Complex example will demonstrate the nearly perfect accuracy compared to software-based PWM-channels by printing the actual elapsed microsecs / millisecs of each type of PWM-channels. Being ISR-based PWM-channels, their executions are not blocked by bad-behaving functions / tasks, such as connecting to WiFi, Internet and Blynk services. You can also have many (up to 16) synchronized PWM-channels to use. This non-being-blocked important feature is absolutely necessary for mission-critical tasks. You'll see 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

How to use

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

Timer0, Timer1, Timer2 and Timer3 are supported for ESP32

Examples:

  1. ISR_16_PWMs_Array
  2. ISR_16_PWMs_Array_Complex
  3. ISR_16_PWMs_Array_Simple
  4. ISR_Changing_PWM
  5. ISR_Modify_PWM
  6. multiFileProject New

Example ISR_16_PWMs_Array_Complex

https://github.com/khoih-prog/ESP32_PWM/blob/bf025f27e40c4b70687cd61a320a63c98bb724ba/examples/ISR_16_PWMs_Array_Complex/ISR_16_PWMs_Array_Complex.ino#L25-L471

Debug Terminal Output Samples

1. ISR_16_PWMs_Array_Complex on ESP32_DEV

The following is the sample terminal output when running example ISR_16_PWMs_Array_Complex on ESP32_DEV to demonstrate 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 ESP32_DEV
ESP32_PWM v1.3.3
CPU Frequency = 240 MHz
[PWM] ESP32_TimerInterrupt: _timerNo = 1 , _fre = 1000000
[PWM] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[PWM] _timerIndex = 1 , _timerGroup = 0
[PWM] _count = 0 - 20
[PWM] timer_set_alarm_value = 20.00
Starting ITimer OK, micros() = 2058708
Channel : 0	    Period : 1000000		OnTime : 50000	Start_Time : 2058897
Channel : 1	    Period : 500000		OnTime : 50000	Start_Time : 2069539
Channel : 2	    Period : 333333		OnTime : 66666	Start_Time : 2069906
Channel : 3	    Period : 250000		OnTime : 75000	Start_Time : 2080530
Channel : 4	    Period : 200000		OnTime : 80000	Start_Time : 2080889
Channel : 5	    Period : 166667		OnTime : 75000	Start_Time : 2091451
Channel : 6	    Period : 142857		OnTime : 71428	Start_Time : 2102051
Channel : 7	    Period : 125000		OnTime : 68750	Start_Time : 2102413
Channel : 8	    Period : 111111		OnTime : 66666	Start_Time : 2113029
Channel : 9	    Period : 100000		OnTime : 65000	Start_Time : 2113401
Channel : 10	    Period : 66667		OnTime : 46666	Start_Time : 2124047
Channel : 11	    Period : 50000		OnTime : 37500	Start_Time : 2124423
Channel : 12	    Period : 40000		OnTime : 32000	Start_Time : 2135081
Channel : 13	    Period : 33333		OnTime : 28333	Start_Time : 2135450
Channel : 14	    Period : 25000		OnTime : 22500	Start_Time : 2146102
Channel : 15	    Period : 20000		OnTime : 19000	Start_Time : 2156669
SimpleTimer (ms): 2000, us : 12156966, Dus : 10098123
PWM Channel : 01000000, programmed Period (us): 1000000, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1500000, programmed Period (us): 500000, actual : 500000, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2333333, programmed Period (us): 333333, actual : 333340, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3250000, programmed Period (us): 250000, actual : 250000, programmed DutyCycle : 30.00, actual : 30.00
PWM Channel : 4200000, programmed Period (us): 200000, actual : 200000, programmed DutyCycle : 40.00, actual : 40.00
PWM Channel : 5166667, programmed Period (us): 166667, actual : 166680, programmed DutyCycle : 45.00, actual : 45.00
PWM Channel : 6142857, programmed Period (us): 142857, actual : 142860, programmed DutyCycle : 50.00, actual : 49.99
PWM Channel : 7125000, programmed Period (us): 125000, actual : 125001, programmed DutyCycle : 55.00, actual : 54.99
PWM Channel : 8111111, programmed Period (us): 111111, actual : 111120, programmed DutyCycle : 60.00, actual : 59.99
PWM Channel : 9100000, programmed Period (us): 100000, actual : 100002, programmed DutyCycle : 65.00, actual : 65.00
PWM Channel : 1066667, programmed Period (us): 66667, actual : 66680, programmed DutyCycle : 70.00, actual : 69.98
PWM Channel : 1150000, programmed Period (us): 50000, actual : 50001, programmed DutyCycle : 75.00, actual : 74.97
PWM Channel : 1240000, programmed Period (us): 40000, actual : 39999, programmed DutyCycle : 80.00, actual : 80.00
PWM Channel : 1333333, programmed Period (us): 33333, actual : 33340, programmed DutyCycle : 85.00, actual : 84.94
PWM Channel : 1425000, programmed Period (us): 25000, actual : 25000, programmed DutyCycle : 90.00, actual : 90.00
PWM Channel : 1520000, programmed Period (us): 20000, actual : 20000, programmed DutyCycle : 95.00, actual : 95.00
SimpleTimer (ms): 2000, us : 22312882, Dus : 10155916
PWM Channel : 01000000, programmed Period (us): 1000000, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1500000, programmed Period (us): 500000, actual : 500000, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2333333, programmed Period (us): 333333, actual : 333340, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3250000, programmed Period (us): 250000, actual : 250000, programmed DutyCycle : 30.00, actual : 30.00
PWM Channel : 4200000, programmed Period (us): 200000, actual : 200000, programmed DutyCycle : 40.00, actual : 40.00
PWM Channel : 5166667, programmed Period (us): 166667, actual : 166680, programmed DutyCycle : 45.00, actual : 45.00
PWM Channel : 6142857, programmed Period (us): 142857, actual : 142861, programmed DutyCycle : 50.00, actual : 49.99
PWM Channel : 7125000, programmed Period (us): 125000, actual : 125000, programmed DutyCycle : 55.00, actual : 54.99
PWM Channel : 8111111, programmed Period (us): 111111, actual : 111120, programmed DutyCycle : 60.00, actual : 59.99
PWM Channel : 9100000, programmed Period (us): 100000, actual : 100001, programmed DutyCycle : 65.00, actual : 65.00
PWM Channel : 1066667, programmed Period (us): 66667, actual : 66680, programmed DutyCycle : 70.00, actual : 69.98
PWM Channel : 1150000, programmed Period (us): 50000, actual : 50000, programmed DutyCycle : 75.00, actual : 75.00
PWM Channel : 1240000, programmed Period (us): 40000, actual : 40000, programmed DutyCycle : 80.00, actual : 80.00
PWM Channel : 1333333, programmed Period (us): 33333, actual : 33340, programmed DutyCycle : 85.00, actual : 84.94
PWM Channel : 1425000, programmed Period (us): 25000, actual : 25000, programmed DutyCycle : 90.00, actual : 90.00
PWM Channel : 1520000, programmed Period (us): 20000, actual : 20000, programmed DutyCycle : 95.00, actual : 95.00

2. ISR_16_PWMs_Array on ESP32_DEV

The following is the sample terminal output when running example ISR_16_PWMs_Array on ESP32_DEV to demonstrate how to use multiple Hardware PWM channels.

Starting ISR_16_PWMs_Array on ESP32_DEV
ESP32_PWM v1.3.3
CPU Frequency = 240 MHz
[PWM] ESP32_TimerInterrupt: _timerNo = 1 , _fre = 1000000
[PWM] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[PWM] _timerIndex = 1 , _timerGroup = 0
[PWM] _count = 0 - 20
[PWM] timer_set_alarm_value = 20.00
Starting ITimer OK, micros() = 2058746
Channel : 0	    Period : 1000000		OnTime : 50000	Start_Time : 2058951
Channel : 1	    Period : 500000		OnTime : 50000	Start_Time : 2069589
Channel : 2	    Period : 333333		OnTime : 66666	Start_Time : 2070006
Channel : 3	    Period : 250000		OnTime : 75000	Start_Time : 2080650
Channel : 4	    Period : 200000		OnTime : 80000	Start_Time : 2081082
Channel : 5	    Period : 166666		OnTime : 74999	Start_Time : 2091764
Channel : 6	    Period : 142857		OnTime : 71428	Start_Time : 2092203
Channel : 7	    Period : 125000		OnTime : 68750	Start_Time : 2102906
Channel : 8	    Period : 111111		OnTime : 66666	Start_Time : 2113570
Channel : 9	    Period : 100000		OnTime : 65000	Start_Time : 2114007
Channel : 10	    Period : 66666		OnTime : 46666	Start_Time : 2124648
Channel : 11	    Period : 50000		OnTime : 37500	Start_Time : 2125104
Channel : 12	    Period : 40000		OnTime : 32000	Start_Time : 2135783
Channel : 13	    Period : 33333		OnTime : 28333	Start_Time : 2136239
Channel : 14	    Period : 25000		OnTime : 22500	Start_Time : 2146919
Channel : 15	    Period : 20000		OnTime : 19000	Start_Time : 2147367

3. ISR_16_PWMs_Array_Simple on ESP32_DEV

The following is the sample terminal output when running example ISR_16_PWMs_Array_Simple on ESP32_DEV to demonstrate how to use multiple Hardware PWM channels.

Starting ISR_16_PWMs_Array_Simple on ESP32_DEV
ESP32_PWM v1.3.3
CPU Frequency = 240 MHz
[PWM] ESP32_TimerInterrupt: _timerNo = 1 , _fre = 1000000
[PWM] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[PWM] _timerIndex = 1 , _timerGroup = 0
[PWM] _count = 0 - 20
[PWM] timer_set_alarm_value = 20.00
Starting ITimer OK, micros() = 2058739
Channel : 0	    Period : 1000000		OnTime : 50000	Start_Time : 2058949
Channel : 1	    Period : 500000		OnTime : 50000	Start_Time : 2069626
Channel : 2	    Period : 333333		OnTime : 66666	Start_Time : 2070013
Channel : 3	    Period : 250000		OnTime : 75000	Start_Time : 2080640
Channel : 4	    Period : 200000		OnTime : 80000	Start_Time : 2081020
Channel : 5	    Period : 166666		OnTime : 74999	Start_Time : 2091664
Channel : 6	    Period : 142857		OnTime : 71428	Start_Time : 2102298
Channel : 7	    Period : 125000		OnTime : 68750	Start_Time : 2102684
Channel : 8	    Period : 111111		OnTime : 66666	Start_Time : 2113302
Channel : 9	    Period : 100000		OnTime : 65000	Start_Time : 2113700
Channel : 10	    Period : 66666		OnTime : 46666	Start_Time : 2124315
Channel : 11	    Period : 50000		OnTime : 37500	Start_Time : 2124701
Channel : 12	    Period : 40000		OnTime : 32000	Start_Time : 2135333
Channel : 13	    Period : 33333		OnTime : 28333	Start_Time : 2135733
Channel : 14	    Period : 25000		OnTime : 22500	Start_Time : 2146377
Channel : 15	    Period : 20000		OnTime : 19000	Start_Time : 2156993

4. ISR_Modify_PWM on ESP32_DEV

The following is the sample terminal output when running example ISR_Modify_PWM on ESP32_DEV to demonstrate how to modify PWM settings on-the-fly without deleting the PWM channel

Starting ISR_Modify_PWM on ESP32_DEV
ESP32_PWM v1.3.3
CPU Frequency = 240 MHz
[PWM] ESP32_TimerInterrupt: _timerNo = 1 , _fre = 1000000
[PWM] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[PWM] _timerIndex = 1 , _timerGroup = 0
[PWM] _count = 0 - 20
[PWM] timer_set_alarm_value = 20.00
Starting ITimer OK, micros() = 2059642
Using PWM Freq = 200.00, PWM DutyCycle = 1.00
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 2060337
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 12071208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 22066228
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 32071347
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 42066348
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 52072208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 62077247
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 72078208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 82078228
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 92078347
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 102073347
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 112079208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 122074208
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 132079347
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 142084368
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 152085208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 162080208

5. ISR_Changing_PWM on ESP32_DEV

The following is the sample terminal output when running example ISR_Changing_PWM on ESP32_DEV 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 ESP32_DEV
ESP32_PWM v1.3.3
CPU Frequency = 240 MHz
[PWM] ESP32_TimerInterrupt: _timerNo = 1 , _fre = 1000000
[PWM] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[PWM] _timerIndex = 1 , _timerGroup = 0
[PWM] _count = 0 - 20
[PWM] timer_set_alarm_value = 20.00
Starting ITimer OK, micros() = 2058761
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 2059443
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 12070335
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 22070374
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 32070329
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 42070352
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 52070349
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 62070352
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 72070329

6. ISR_Modify_PWM on ESP32S2_DEV

The following is the sample terminal output when running example ISR_Modify_PWM on ESP32S2_DEV to demonstrate how to modify PWM settings on-the-fly without deleting the PWM channel

Starting ISR_Modify_PWM on ESP32S2_DEV
ESP32_PWM v1.3.3
CPU Frequency = 240 MHz
[PWM] ESP32_S2_TimerInterrupt: _timerNo = 1 , _fre = 1000000
[PWM] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[PWM] _timerIndex = 1 , _timerGroup = 0
[PWM] _count = 0 - 20
[PWM] timer_set_alarm_value = 20.00
Starting ITimer OK, micros() = 2059642
Using PWM Freq = 200.00, PWM DutyCycle = 1.00
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 2060337
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 12071208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 22066228
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 32071347
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 42066348
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 52072208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 62077247
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 72078208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 82078228
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 92078347
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 102073347
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 112079208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 122074208
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 132079347
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 142084368
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 152085208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 162080208

7. ISR_Changing_PWM on ESP32S2_DEV

The following is the sample terminal output when running example ISR_Changing_PWM on ESP32S2_DEV 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 ESP32S2_DEV
ESP32_PWM v1.3.3
CPU Frequency = 240 MHz
[PWM] ESP32_S2_TimerInterrupt: _timerNo = 1 , _fre = 1000000
[PWM] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[PWM] _timerIndex = 1 , _timerGroup = 0
[PWM] _count = 0 - 20
[PWM] timer_set_alarm_value = 20.00
Starting ITimer OK, micros() = 2563689
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 2568686
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 12578679
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 22583648
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 32583648

8. ISR_Modify_PWM on ESP32C3_DEV

The following is the sample terminal output when running example ISR_Modify_PWM on ESP32C3_DEV to demonstrate how to modify PWM settings on-the-fly without deleting the PWM channel

Starting ISR_Modify_PWM on ESP32C3_DEV
ESP32_PWM v1.3.3
CPU Frequency = 160 MHz
[PWM] ESP32_TimerInterrupt: _timerNo = 1 , _fre = 1000000
[PWM] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[PWM] _timerIndex = 0 , _timerGroup = 1
[PWM] _count = 0 - 20
[PWM] timer_set_alarm_value = 20.00
Starting ITimer OK, micros() = 2059642
Using PWM Freq = 200.00, PWM DutyCycle = 1.00
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 2060337
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 12071208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 22066228
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 32071347
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 42066348
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 52072208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 62077247
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 72078208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 82078228
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 92078347
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 102073347
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 112079208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 122074208
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 132079347
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 142084368
Channel : 0	    Period : 10000		OnTime : 555	Start_Time : 152085208
Channel : 0	    Period : 5000		OnTime : 50	Start_Time : 162080208

9. ISR_Changing_PWM on ESP32C3_DEV

The following is the sample terminal output when running example ISR_Changing_PWM on ESP32C3_DEV 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 ESP32C3_DEV
ESP32_PWM v1.3.3
CPU Frequency = 160 MHz
[PWM] ESP32_TimerInterrupt: _timerNo = 1 , _fre = 1000000
[PWM] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[PWM] _timerIndex = 0 , _timerGroup = 1
[PWM] _count = 0 - 20
[PWM] timer_set_alarm_value = 20.00
Starting ITimer OK, micros() = 2100339
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 2105212
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 12117109
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 22122103
Using PWM Freq = 2.00, PWM DutyCycle = 90.00
Channel : 0	    Period : 500000		OnTime : 450000	Start_Time : 32122107
Using PWM Freq = 1.00, PWM DutyCycle = 50.00
Channel : 0	    Period : 1000000		OnTime : 500000	Start_Time : 42127102

10. ISR_16_PWMs_Array_Complex on ESP32S3_DEV

The following is the sample terminal output when running example ISR_16_PWMs_Array_Complex on ESP32S3_DEV to demonstrate 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 ESP32S3_DEV
ESP32_PWM v1.3.3
CPU Frequency = 240 MHz
[PWM] ESP32_S3_TimerInterrupt: _timerNo = 1 , _fre = 1000000
[PWM] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[PWM] _timerIndex = 1 , _timerGroup = 0
[PWM] _count = 0 - 20
[PWM] timer_set_alarm_value = 20.00
Starting ITimer OK, micros() = 2118162
Channel : 0	    Period : 1000000		OnTime : 50000	Start_Time : 2118373
Channel : 1	    Period : 500000		OnTime : 50000	Start_Time : 2128833
Channel : 2	    Period : 333333		OnTime : 66666	Start_Time : 2129071
Channel : 3	    Period : 250000		OnTime : 75000	Start_Time : 2139568
Channel : 4	    Period : 200000		OnTime : 80000	Start_Time : 2150027
Channel : 5	    Period : 166667		OnTime : 75000	Start_Time : 2150272
Channel : 6	    Period : 142857		OnTime : 71428	Start_Time : 2160711
Channel : 7	    Period : 125000		OnTime : 68750	Start_Time : 2160971
Channel : 8	    Period : 111111		OnTime : 66666	Start_Time : 2171464
Channel : 9	    Period : 100000		OnTime : 65000	Start_Time : 2171714
Channel : 10	    Period : 66667		OnTime : 46666	Start_Time : 2182194
Channel : 11	    Period : 50000		OnTime : 37500	Start_Time : 2192697
Channel : 12	    Period : 40000		OnTime : 32000	Start_Time : 2192958
Channel : 13	    Period : 33333		OnTime : 28333	Start_Time : 2203438
Channel : 14	    Period : 25000		OnTime : 22500	Start_Time : 2203696
Channel : 15	    Period : 20000		OnTime : 19000	Start_Time : 2214155
SimpleTimer (ms): 2000, us : 12214398, Dus : 10096157
PWM Channel : 01000000, programmed Period (us): 1000000, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1500000, programmed Period (us): 500000, actual : 500000, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2333333, programmed Period (us): 333333, actual : 333340, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3250000, programmed Period (us): 250000, actual : 249999, programmed DutyCycle : 30.00, actual : 30.00
PWM Channel : 4200000, programmed Period (us): 200000, actual : 200000, programmed DutyCycle : 40.00, actual : 40.00
PWM Channel : 5166667, programmed Period (us): 166667, actual : 166680, programmed DutyCycle : 45.00, actual : 45.00
PWM Channel : 6142857, programmed Period (us): 142857, actual : 142860, programmed DutyCycle : 50.00, actual : 49.99
PWM Channel : 7125000, programmed Period (us): 125000, actual : 125000, programmed DutyCycle : 55.00, actual : 54.99
PWM Channel : 8111111, programmed Period (us): 111111, actual : 111120, programmed DutyCycle : 60.00, actual : 59.99
PWM Channel : 9100000, programmed Period (us): 100000, actual : 100001, programmed DutyCycle : 65.00, actual : 65.00
PWM Channel : 1066667, programmed Period (us): 66667, actual : 66680, programmed DutyCycle : 70.00, actual : 69.98
PWM Channel : 1150000, programmed Period (us): 50000, actual : 50000, programmed DutyCycle : 75.00, actual : 75.00
PWM Channel : 1240000, programmed Period (us): 40000, actual : 40000, programmed DutyCycle : 80.00, actual : 80.00
PWM Channel : 1333333, programmed Period (us): 33333, actual : 33340, programmed DutyCycle : 85.00, actual : 84.94
PWM Channel : 1425000, programmed Period (us): 25000, actual : 25000, programmed DutyCycle : 90.00, actual : 90.00
PWM Channel : 1520000, programmed Period (us): 20000, actual : 19999, programmed DutyCycle : 95.00, actual : 95.00
SimpleTimer (ms): 2000, us : 22375317, Dus : 10160919
PWM Channel : 01000000, programmed Period (us): 1000000, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1500000, programmed Period (us): 500000, actual : 500000, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2333333, programmed Period (us): 333333, actual : 333340, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3250000, programmed Period (us): 250000, actual : 250001, programmed DutyCycle : 30.00, actual : 30.00
PWM Channel : 4200000, programmed Period (us): 200000, actual : 200000, programmed DutyCycle : 40.00, actual : 40.00
PWM Channel : 5166667, programmed Period (us): 166667, actual : 166680, programmed DutyCycle : 45.00, actual : 45.00
PWM Channel : 6142857, programmed Period (us): 142857, actual : 142860, programmed DutyCycle : 50.00, actual : 49.99
PWM Channel : 7125000, programmed Period (us): 125000, actual : 125000, programmed DutyCycle : 55.00, actual : 54.99
PWM Channel : 8111111, programmed Period (us): 111111, actual : 111120, programmed DutyCycle : 60.00, actual : 59.99
PWM Channel : 9100000, programmed Period (us): 100000, actual : 100000, programmed DutyCycle : 65.00, actual : 65.00
PWM Channel : 1066667, programmed Period (us): 66667, actual : 66679, programmed DutyCycle : 70.00, actual : 69.98
PWM Channel : 1150000, programmed Period (us): 50000, actual : 50000, programmed DutyCycle : 75.00, actual : 75.00
PWM Channel : 1240000, programmed Period (us): 40000, actual : 40000, programmed DutyCycle : 80.00, actual : 80.00
PWM Channel : 1333333, programmed Period (us): 33333, actual : 33340, programmed DutyCycle : 85.00, actual : 84.94
PWM Channel : 1425000, programmed Period (us): 25000, actual : 25000, programmed DutyCycle : 90.00, actual : 90.00
PWM Channel : 1520000, programmed Period (us): 20000, actual : 20000, programmed DutyCycle : 95.00, actual : 95.00
SimpleTimer (ms): 2000, us : 32536323, Dus : 10161006
PWM Channel : 01000000, programmed Period (us): 1000000, actual : 1000000, programmed DutyCycle : 5.00, actual : 5.00
PWM Channel : 1500000, programmed Period (us): 500000, actual : 500000, programmed DutyCycle : 10.00, actual : 10.00
PWM Channel : 2333333, programmed Period (us): 333333, actual : 333340, programmed DutyCycle : 20.00, actual : 20.00
PWM Channel : 3250000, programmed Period (us): 250000, actual : 250001, programmed DutyCycle : 30.00, actual : 30.00
PWM Channel : 4200000, programmed Period (us): 200000, actual : 200000, programmed DutyCycle : 40.00, actual : 40.00
PWM Channel : 5166667, programmed Period (us): 166667, actual : 166680, programmed DutyCycle : 45.00, actual : 45.00
PWM Channel : 6142857, programmed Period (us): 142857, actual : 142861, programmed DutyCycle : 50.00, actual : 49.99
PWM Channel : 7125000, programmed Period (us): 125000, actual : 125000, programmed DutyCycle : 55.00, actual : 54.99
PWM Channel : 8111111, programmed Period (us): 111111, actual : 111120, programmed DutyCycle : 60.00, actual : 59.99
PWM Channel : 9100000, programmed Period (us): 100000, actual : 100000, programmed DutyCycle : 65.00, actual : 64.98
PWM Channel : 1066667, programmed Period (us): 66667, actual : 66680, programmed DutyCycle : 70.00, actual : 69.98
PWM Channel : 1150000, programmed Period (us): 50000, actual : 50000, programmed DutyCycle : 75.00, actual : 75.00
PWM Channel : 1240000, programmed Period (us): 40000, actual : 40001, programmed DutyCycle : 80.00, actual : 80.00
PWM Channel : 1333333, programmed Period (us): 33333, actual : 33340, programmed DutyCycle : 85.00, actual : 84.94
PWM Channel : 1425000, programmed Period (us): 25000, actual : 25000, programmed DutyCycle : 90.00, actual : 90.01
PWM Channel : 1520000, programmed Period (us): 20000, actual : 20000, programmed DutyCycle : 95.00, actual : 95.00

Debug

Debug is enabled by default on Serial.

You can also change the debugging level _PWM_LOGLEVEL_ from 0 to 4

// 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

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: ESP32_PWM issues

TO DO

  1. Search for bug and improvement.
  2. Similar features for remaining Arduino boards such as SAMD21, SAMD51, SAM-DUE, nRF52, ESP8266, STM32, Portenta_H7, RP2040, etc.

DONE

  1. Basic hardware PWM-channels for ESP32, ESP32_C2 and ESP32_C3 for ESP32 core v2.0.0+
  2. Longer time interval
  3. Add complex examples.
  4. Add functions to modify PWM settings on-the-fly
  5. Fix examples to use with ESP32 core v2.0.1+
  6. Fix multiple-definitions linker error. Drop src_cpp and src_h directories
  7. Add example multiFileProject to demo for multiple-file project
  8. Improve accuracy by using float, instead of uint32_t for dutycycle
  9. DutyCycle to be optionally updated at the end current PWM period instead of immediately.
  10. Add support to ESP32-S3
  11. Display informational warning only when _PWM_LOGLEVEL_ > 3
  12. Remove crashing PIN_D24 from examples

Contributions and Thanks

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

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

Copyright

Copyright 2021- Khoi Hoang

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Metadata

This library enables you to use Interrupt from Hardware Timers on an ESP32, ESP32_S2 or ESP32_C3-based board to create and output PWM to pins. It now supports 16 ISR-based synchronized PWM channels, w...

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