25 pwm pins can be used on mega2560 ? i can't add more then 20 ?

[Vincenttor]

Hi guys,

i had a great idea for my workshop lights ( led panels) to make them dimmable since there 40Watts each and power is "expensive" in Europe.

Now i am running the beta arduino version so i could use 25 pwm pins.
not sure whats going on but here is a video where i can't add any more then 20.
I can add the pins to outputs etc but pwm is like it has been locked.

Did i miss something in the manual ?




Video you can find here :

[enigmatheatre]

Yep, My bad I have just looked at the code and it is limited to 20 PWM pins and I did not update the manual. I also somehow missed returning the info to tell you that in the log. It has been like this for years and you are the first to notice.

[Vincenttor]

Ah that's a pity.
Can this limit easily be lifted/raised to 25 ? or is it limited in the code because of a hardware limit ?



edit: i do see in softpwm.h this :
#define SOFTPWM_MAXCHANNELS 20

Going to change it to 25 and see if it really would be this simple 😀

[enigmatheatre]

Unfortunately, this is not something I can change as the size of the sketch is a problem on some boards and I need to make it universal. Do you need to control all 25 lamps independently or can you not daisy chain the drivers?

[enigmatheatre]

edit: i do see in softpwm.h this :
#define SOFTPWM_MAXCHANNELS 20

Going to change it to 25 and see if it really would be this simple 😀

If only! there are other arrays that need to change and the plugin is coded to limit the pin setup to 20 as you have found.

[Vincenttor]

no ill just take 1 board away and use a esp8266 for controller this one.
Also let's the mega breath a bit since it isnt the fastest board as far i know.

Thanks anyway for the fast replies, the rest works great here with your plugin as always.

I hoped it was this easy with changing the line , as it did for taking away the flickering by raising the Hz in softpwm.cpp/h
But after reading a threat about 20 softpwm limit it was wiser to go for a hardware solution as i understand by most of the replies instead of taking the time to rewrite a library.
And also risking that the arduino itself couldn't handle it.