- Why do we need this megaAVR_PWM library
- Changelog
- Prerequisites
- Installation
- More useful Information
- Usage
- Examples
- Example PWM_Multi
- Debug Terminal Output Samples
- Debug
- Troubleshooting
- Issues
- TO DO
- DONE
- Contributions and Thanks
- Contributing
- License
- Copyright
Why do we need this megaAVR_PWM library
This hardware-based PWM library enables you to use Hardware-PWM on megaAVR-based boards to create and output PWM. These purely hardware-based PWM channels can generate very high PWM frequencies, depending on CPU clock and acceptable accuracy, due to 8 or 16-bit PWM / Timer registers.
This library is using the same or similar functions as other FastPWM libraries, as follows, to enable you to port your PWM code easily between platforms
- RP2040_PWM
- AVR_PWM
- megaAVR_PWM
- ESP32_FastPWM
- SAMD_PWM
- SAMDUE_PWM
- nRF52_PWM
- Teensy_PWM
- ATtiny_PWM
- Dx_PWM
- Portenta_H7_PWM
- MBED_RP2040_PWM
- nRF52_MBED_PWM
- STM32_PWM
The most important feature is they're purely hardware-based PWM channels. Therefore, their operations are not blocked by bad-behaving software functions / tasks.
This important feature is absolutely necessary for mission-critical tasks. These hardware PWM-channels, still work even if other software 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 control external systems (Servo, etc.) requiring better accuracy.
New efficient setPWM_manual()
function enables waveform creation using PWM.
The PWM_Multi example will demonstrate the usage of multichannel PWM using multiple Hardware-PWM blocks (slices). The 2 independent Hardware-PWM channels are used to control 2 different PWM outputs, with totally independent frequencies and dutycycles on Arduino Mega
.
Being hardware-based PWM, their executions are not blocked by bad-behaving functions / tasks, such as connecting to WiFi, Internet or Blynk services.
This non-being-blocked important feature is absolutely necessary for mission-critical tasks.
Imagine you have a system with a mission-critical function, controlling a robot 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 hardware-based PWM
.
These hardware-based PWM channels still work even if other software functions are blocking. Moreover, they are much more precise (certainly depending on clock frequency accuracy) than other software-based PWMs, using millis() or micros().
Functions using normal software-based PWMs, 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.
- megaAVR-based boards such as UNO WiFi Rev2, AVR_Nano_Every, etc., using
Arduino megaAVR core
- megaAVR-based boards such as UNO WiFi Rev2, AVR_Nano_Every, ATmega4809, ATmega4808, ATmega3209, ATmega3208, ATmega1609, ATmega1608, ATmega809, ATmega808, etc., using
MegaCoreX megaAVR core
Arduino IDE 1.8.19
for Arduino.Arduino megaAVR core 1.8.7
for Arduino megaAVR boards. . Use Arduino Board Manager to install.MegaCoreX megaAVR core 1.1.1
for Arduino megaAVR boards. . Follow How to install.
The best and easiest way is to use Arduino Library Manager
. Search for megaAVR_PWM, then select / install the latest version.
You can also use this link for more detailed instructions.
Another way to install is to:
- Navigate to megaAVR_PWM page.
- Download the latest release
megaAVR_PWM-main.zip
. - Extract the zip file to
megaAVR_PWM-main
directory - Copy whole
megaAVR_PWM-main
folder to Arduino libraries' directory such as~/Arduino/libraries/
.
- Install VS Code
- Install PlatformIO
- Install megaAVR_PWM library by using Library Manager. Search for megaAVR_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
TCB0-TCB3 are 16-bit timers.
Before using any Timer, you have to make sure the Timer has not been used by any other purpose.
/******************************************************************************************************************************
Pins can be used for hardware-PWM
// For ATmega4809 (Nano Every, Uno WiFi Rev2, etc.)
TCA0 (16-bit) used by PWM generation on pins 5, 9 and 10
TCB0 (16-bit) used by PWM generation on pin 6
TCB1 (16-bit) used by PWM generation on pin 3
TCB2 (16-bit)
TCB3 (16-bit)
////////////////////////////////////////////
// For ATmega4809 (Nano Every, Uno WiFi Rev2, etc.)
Pin 3 => TIMERB1, // 3 PF5, 8-bit PWM, 16-bit counter
Pin 5 => TIMERA0, // 5 PB2, 16-bit PWM, 16-bit counter
Pin 6 => TIMERB0, // 6 PF4, 8-bit PWM, 16-bit counter
Pin 9 => TIMERA0, // 9 PB0, 16-bit PWM, 16-bit counter
Pin 10 => TIMERA0, // 10 PB1, 16-bit PWM, 16-bit counter
////////////////////////////////////////////
******************************************************************************************************************************/
Before using any PWM Timer
and channel
, you have to make sure the Timer
and channel
has not been used by any other purpose.
megaAVR_PWM* PWM_Instance;
PWM_Instance = new megaAVR_PWM(PWM_Pins, freq, dutyCycle);
if (PWM_Instance)
{
PWM_Instance->setPWM();
}
To use float new_dutyCycle
PWM_Instance->setPWM(PWM_Pins, new_frequency, new_dutyCycle);
such as
dutyCycle = 10.0f;
Serial.print(F("Change PWM DutyCycle to ")); Serial.println(dutyCycle);
PWM_Instance->setPWM(pinToUse, frequency, dutyCycle);
To use uint32_t new_dutyCycle
= (real_dutyCycle * 65536) / 100
PWM_Instance->setPWM_Int(PWM_Pins, new_frequency, new_dutyCycle);
such as for real_dutyCycle = 50%
// 50% dutyCycle = (real_dutyCycle * 65535) / 100
dutyCycle = 32767;
Serial.print(F("Change PWM DutyCycle to (%) "));
Serial.println((float) dutyCycle * 100 / 65536);
PWM_Instance->setPWM_Int(pinToUse, frequency, dutyCycle);
for real_dutyCycle = 50%
// 20% dutyCycle = (real_dutyCycle * 65535) / 100
dutyCycle = 13107;
Serial.print(F("Change PWM DutyCycle to (%) "));
Serial.println((float) dutyCycle * 100 / 65536);
PWM_Instance->setPWM_Int(pinToUse, frequency, dutyCycle);
Function prototype
bool setPWM_manual(const uint8_t& pin, const uint16_t& DCValue);
Need to call only once for each pin
PWM_Instance->setPWM(PWM_Pins, frequency, dutyCycle);
after that, if just changing dutyCycle
/ level
, use
PWM_Instance->setPWM_manual(PWM_Pins, new_level);
- PWM_Basic
- PWM_DynamicDutyCycle
- PWM_DynamicDutyCycle_Int
- PWM_DynamicFreq
- PWM_Multi
- PWM_MultiChannel
- PWM_Waveform
- PWM_StepperControl New
Example PWM_Multi
megaAVR_PWM/examples/PWM_Multi/PWM_Multi.ino
Lines 11 to 136 in 7c73a23
The following is the sample terminal output when running example PWM_DynamicDutyCycle on megaAVR Nano Every using MegaCoreX
, to demonstrate the ability to provide high PWM frequencies and ability to change DutyCycle on-the-fly
.
Starting PWM_DynamicDutyCycle on MegaCoreX Nano Every
megaAVR_PWM v1.0.1
[PWM] megaAVR_PWM: _dutycycle = 32767
[PWM] setPWM_Int: input dutycycle = 127
[PWM] setPWM_Int: _timer = 3
[PWM] setPeriod_TimerB: F_CPU = 16000000 , cycles = 3200
[PWM] setPeriod_TimerB: cycles < TIMERB_RESOLUTION * 64, using divider = 64
[PWM] setPeriod_TimerB: pwmPeriod = 50 , _actualFrequency = 5000.00
[PWM] setPWM_Int: TIMERB, _dutycycle = 24 , DC % = 50.00
=====================================================================================
Change PWM DutyCycle to 90.00
[PWM] setPWM: _dutycycle = 58981
[PWM] setPWM_Int: input dutycycle = 230
[PWM] setPWM_Int: _timer = 3
[PWM] setPeriod_TimerB: F_CPU = 16000000 , cycles = 16000
[PWM] setPeriod_TimerB: cycles < TIMERB_RESOLUTION * 64, using divider = 64
[PWM] setPeriod_TimerB: pwmPeriod = 250 , _actualFrequency = 1000.00
[PWM] setPWM_Int: TIMERB, _dutycycle = 224 , DC % = 90.00
=====================================================================================
Actual data: pin = 3, PWM DC = 90.00, PWMPeriod = 250.00, PWM Freq (Hz) = 1000.0000
=====================================================================================
Change PWM DutyCycle to 10.00
[PWM] setPWM: _dutycycle = 6553
[PWM] setPWM_Int: input dutycycle = 25
[PWM] setPWM_Int: _timer = 3
[PWM] setPeriod_TimerB: F_CPU = 16000000 , cycles = 16000
[PWM] setPeriod_TimerB: cycles < TIMERB_RESOLUTION * 64, using divider = 64
[PWM] setPeriod_TimerB: pwmPeriod = 250 , _actualFrequency = 1000.00
[PWM] setPWM_Int: TIMERB, _dutycycle = 24 , DC % = 10.00
=====================================================================================
Actual data: pin = 3, PWM DC = 10.00, PWMPeriod = 250.00, PWM Freq (Hz) = 1000.0000
=====================================================================================
Change PWM DutyCycle to 90.00
[PWM] setPWM: _dutycycle = 58981
[PWM] setPWM_Int: input dutycycle = 230
[PWM] setPWM_Int: _timer = 3
[PWM] setPeriod_TimerB: F_CPU = 16000000 , cycles = 16000
[PWM] setPeriod_TimerB: cycles < TIMERB_RESOLUTION * 64, using divider = 64
[PWM] setPeriod_TimerB: pwmPeriod = 250 , _actualFrequency = 1000.00
[PWM] setPWM_Int: TIMERB, _dutycycle = 224 , DC % = 90.00
=====================================================================================
Actual data: pin = 3, PWM DC = 90.00, PWMPeriod = 250.00, PWM Freq (Hz) = 1000.0000
=====================================================================================
The following is the sample terminal output when running example PWM_Multi on megaAVR Nano Every, to demonstrate the ability to provide high PWM frequencies on multiple PWM-capable
pins.
Starting PWM_Multi on megaAVR Nano Every
megaAVR_PWM v1.0.1
=====================================================================================
Index Pin PWM_freq DutyCycle Actual Freq
=====================================================================================
0 3 1000.00 10.00 1000.0000
1 6 4000.00 50.00 4000.0000
=====================================================================================
Actual data: pin = 3, PWM DC = 10.00, PWMPeriod = 250.00, PWM Freq (Hz) = 1000.0000
=====================================================================================
=====================================================================================
Actual data: pin = 6, PWM DC = 50.00, PWMPeriod = 62.00, PWM Freq (Hz) = 4000.0000
=====================================================================================
The following is the sample terminal output when running example PWM_DynamicFreq on megaAVR Nano Every, to demonstrate the ability to change dynamically PWM frequencies.
Starting PWM_DynamicFreq on megaAVR Nano Every
megaAVR_PWM v1.0.1
[PWM] megaAVR_PWM: _dutycycle = 32767
[PWM] setPWM_Int: input dutycycle = 127
[PWM] setPWM_Int: _timer = 3
[PWM] setPeriod_TimerB: F_CPU = 16000000 , cycles = 16000
[PWM] setPeriod_TimerB: cycles < TIMERB_RESOLUTION * 64, using divider = 64
[PWM] setPeriod_TimerB: pwmPeriod = 250 , _actualFrequency = 1000.00
[PWM] setPWM_Int: TIMERB, _dutycycle = 124 , DC % = 50.00
=====================================================================================
Change PWM Freq to 4000.00
[PWM] setPWM: _dutycycle = 32767
[PWM] setPWM_Int: input dutycycle = 127
[PWM] setPWM_Int: _timer = 3
[PWM] setPeriod_TimerB: F_CPU = 16000000 , cycles = 4000
[PWM] setPeriod_TimerB: cycles < TIMERB_RESOLUTION * 64, using divider = 64
[PWM] setPeriod_TimerB: pwmPeriod = 62 , _actualFrequency = 4000.00
[PWM] setPWM_Int: TIMERB, _dutycycle = 30 , DC % = 50.00
=====================================================================================
Actual data: pin = 3, PWM DC = 50.00, PWMPeriod = 62.00, PWM Freq (Hz) = 4000.0000
=====================================================================================
Change PWM Freq to 1000.00
[PWM] setPWM: _dutycycle = 32767
[PWM] setPWM_Int: input dutycycle = 127
[PWM] setPWM_Int: _timer = 3
[PWM] setPeriod_TimerB: F_CPU = 16000000 , cycles = 16000
[PWM] setPeriod_TimerB: cycles < TIMERB_RESOLUTION * 64, using divider = 64
[PWM] setPeriod_TimerB: pwmPeriod = 250 , _actualFrequency = 1000.00
[PWM] setPWM_Int: TIMERB, _dutycycle = 124 , DC % = 50.00
=====================================================================================
Actual data: pin = 3, PWM DC = 50.00, PWMPeriod = 250.00, PWM Freq (Hz) = 1000.0000
=====================================================================================
The following is the sample terminal output when running example PWM_Waveform on megaAVR Nano Every, to demonstrate how to use the setPWM_manual()
function in wafeform creation
Starting PWM_Waveform on megaAVR Nano Every
megaAVR_PWM v1.0.1
[PWM] megaAVR_PWM: _dutycycle = 0
[PWM] setPWM: _dutycycle = 0
[PWM] setPWM_Int: input dutycycle = 0
[PWM] setPWM_Int: _timer = 3
[PWM] setPeriod_TimerB: F_CPU = 16000000 , cycles = 16000
[PWM] setPeriod_TimerB: cycles < TIMERB_RESOLUTION * 64, using divider = 64
[PWM] setPeriod_TimerB: pwmPeriod = 250 , _actualFrequency = 1000.00
[PWM] setPWM_Int: TIMERB, _dutycycle = 0 , DC % = 0.40
============================================================================================
Actual data: pin = 3, PWM DutyCycle = 0.40, PWMPeriod = 250.00, PWM Freq (Hz) = 1000.0000
============================================================================================
[PWM] PWM enabled, DCValue = 0 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 15 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 31 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 46 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 62 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 78 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 93 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 109 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 125 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 140 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 156 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 171 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 187 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 203 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 218 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 234 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 250 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 234 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 218 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 203 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 187 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 171 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 156 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 140 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 125 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 109 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 93 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 78 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 62 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 46 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 31 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 15 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
[PWM] PWM enabled, DCValue = 0 , pwmPeriod = 250 , _frequency = 1000.00 , _actualFrequency = 1000.00
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
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.
Submit issues to: megaAVR_PWM issues
- Search for bug and improvement.
- Similar features for remaining Arduino boards
- Basic hardware-based multi-channel PWMs for megaAVR-based boards such as
UNO WiFi Rev2
,AVR_Nano_Every
, etc.**, using either
- Add example PWM_StepperControl to demo how to control Stepper Motor using PWM
Many thanks for everyone for bug reporting, new feature suggesting, testing and contributing to the development of this library.
- Thanks to Paul van Dinther for proposing new way to use PWM to drive Stepper-Motor in Using PWM to step a stepper driver #16, leading to v2.0.3
Paul van Dinther |
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
- The library is licensed under MIT
Copyright (c) 2022- Khoi Hoang