I need some help porting code using PWM16.h to this library

[glennblock]

Hi everyone

I have Artisan’s roaster sketch running fine on my Arduino Uno Rev 3. I purchased an Uno WiFi Rev 2 and the sketch won’t compile because the PWM16 lib is not supported for the new chipset.

I understand how PWM works and can see what the current library is doing, can someone tell me looking at this code

https://github.com/greencardigan/TC4-shield/blob/master/applications/Artisan/aArtisan_PID/trunk/src/aArtisanQ_PID/aArtisanQ_PID.ino

What would I need to change to use this new mega avr lib? See the ssr variable

Also please tell me if I am completely off on what I am asking.

Thanks!

[khoih-prog]

Hi @glennblock

https://github.com/nicolaskruchten/arduino/blob/fc8b5804fc2da155384c528dfd2be0d629bba816/libraries/PWM16/PWM16.h#L96-L109

#define pwmN128Hz 127    // TOP values for various frequencies
#define pwmN64Hz  255
#define pwmN60Hz  272  // approx.; exact = 272.0667
#define pwmN50Hz  327  // approx.; exact = 326.68
#define pwmN32Hz  511
#define pwmN30Hz  545  // approx.; exact = 545.1333
#define pwmN16Hz  1023
#define pwmN8Hz   2047
#define pwmN4Hz   4095
#define pwmN2Hz   8191
#define pwmN1Hz   16383
#define pwmN1sec  16383
#define pwmN2sec  32767
#define pwmN4sec  65535

As you're using very low frequency, I suggest you start with the megaAVR_Slow_PWM library, designed specifically for low-frequency applications

Check Features

Very simple to convert from PWM16 to megaAVR_Slow_PWM library.

Check the simple example

1. ISR_8_PWMs_Array_Simple

---

#define pwmOutA 9   // pin 9
#define pwmOutB 10  // pin 10

In PWM16 library, the function Out() outputs dutyA and dutyB (from 0-100) to pin 9 and 10

void Out( unsigned int dutyA, unsigned int dutyB );

The matching functions you possibly can use are

https://github.com/khoih-prog/megaAVR_Slow_PWM/blob/54981c2b689e3fed64ab331ae5d626ab3e0fa541/src/megaAVR_Slow_PWM_ISR.hpp#L176

https://github.com/khoih-prog/megaAVR_Slow_PWM/blob/54981c2b689e3fed64ab331ae5d626ab3e0fa541/src/megaAVR_Slow_PWM_ISR.hpp#L166-L167

bool modifyPWMChannel(const uint8_t& channelNum, const uint32_t& pin, const float& frequency, const float& dutycycle);
int setPWM_Period(const uint32_t& pin, const uint32_t& period, const float& dutycycle, 
                      timer_callback StartCallback = nullptr, timer_callback StopCallback = nullptr)  ;

Good Luck,

[glennblock]

Thank you for the quick response! Looking at the code wouldn't int setPWM(const uint32_t& pin, const float& frequency, const float& dutycycle, timer_callback StartCallback = nullptr, timer_callback StopCallback = nullptr) be fine?

[khoih-prog]

It's easier to use setPWM or setPWM_Period() function.

The channelNum (max 16 channel for each Timer) is assigned uniquely for each pin, to be used later when necessary.

Please check and run example ISR_Modify_PWM for how to use.

#if USING_PWM_FREQUENCY

  // You can use this with PWM_Freq in Hz
  ISR_PWM.setPWM(PWM_Pin, PWM_Freq1, PWM_DutyCycle1);

#else
#if USING_MICROS_RESOLUTION
  // Or using period in microsecs resolution
  channelNum = ISR_PWM.setPWM_Period(PWM_Pin, PWM_Period1, PWM_DutyCycle1);
#else
  // Or using period in millisecs resolution
  channelNum = ISR_PWM.setPWM_Period(PWM_Pin, PWM_Period1 / 1000, PWM_DutyCycle1);
#endif
#endif

[khoih-prog]

I've just un-archived the megaAVR_Slow_PWM so that you can post the issue there if you decide to use it.

[glennblock]

@khoih-prog the newer version of the PWM16 also supports fast PWM on IO3. https://github.com/Roastr/TC4-Shield/blob/main/applications/libraries/trunk/libraries/PWM16/PWM16.h which the sketch also uses.

I tried including both fast and slow versions but I am getting errors due to redeclarations of variables. Does megaAVR_PWM support both fast and slow?

In file included from /Users/glennblock/src/TC4-shield/applications/Artisan/aArtisan_PID/trunk/src/aArtisanQ_PID/aArtisanQ_PID.ino:309:0:
/Users/glennblock/Documents/Arduino/libraries/megaAVR_PWM/src/megaAVR_PWM.h:222:16: error: redeclaration of 'HW_TIMER_0'
   HW_TIMER_0 = 0,
                ^
In file included from /Users/glennblock/Documents/Arduino/libraries/megaAVR_Slow_PWM/src/megaAVR_Slow_PWM.h:29:0,
                 from /Users/glennblock/src/TC4-shield/applications/Artisan/aArtisan_PID/trunk/src/aArtisanQ_PID/aArtisanQ_PID.ino:301:
/Users/glennblock/Documents/Arduino/libraries/megaAVR_Slow_PWM/src/megaAVR_Slow_PWM.hpp:99:3: note: previous declaration '<unnamed enum> HW_TIMER_0'
   HW_TIMER_0 = 0,

[khoih-prog]

Sorry the 2 libraries are not designed to coexist yet. Therefore, conflict in declarations happens.

megaAVR_PWM only supports Fast-PWM, while megaAVR_Slow_PWM only supports Slow-PWM