I have a sketch that's running slow and I thought,

I have a sketch that’s running slow and I thought, can I just show (send data) only the leds that were updated or does FastLed do this already?

@Stephen_Kramer unfortunately no. All the led must be displayed.
Could we know what you are trying to achieve as maybe share the code ? Which controller are you using for which led type ?

Depending on your controller and LED chipset, you could look into FastLED’s parallel output functionality to speed things up.

I’ll take a wild guess and say that WS2812’s ARE notoriously slow in larger installations, which is why parallelism is so important with them.

Yes I have a strand of 265 WS2812Bs on my house that I animate for a variety of occasions. But I found the main problems with the sketch, it used the pow() function a lot and when I replaced it with a combination of FastLED lib8tion functions it runs very smooth. Parallel output is next on my list to learn. Which strand do you recommend for a faster data update ? I’ll post the sketch probably this weekend with a vid of the animation.

@Stephen_Kramer FastLED math is FAST math. I prefer APA102’s because I avoid interrupt issues.

Just remember, we still don’t know much about your setup except that it’s currently running WS2812’s and is 265 in length. Could be running on one of over a dozen different microcontrollers.

It’s running great now, on Esp8266 Wemos D1 Mini R2 @ 160 MHz . I was trying to update every 25ms so I guess that’s 265340 ~ 32 kB/s ?

@Stephen_Kramer the time needed to display to update the strip is 265*30E-9~8ms for ws2812. So you have 17ms to run code.

Thanks. Let me tell you, I started using Blynk to tune in my display parameters and I have done more work tonight in 15 minutes than I have all day long earlier today! I could have been using analog pins but Blynk is a great alternative, just save the values to EEPROM or SPIFFS when your done, no hardware required! Could also write a webserver but I’m not yet HTTP savvy.

@Stephen_Kramer what is Blynk exactly ?

@Yves_BAZIN I’ve only played with it a tiny bit, but it’s actually very cool. Check it out.

You make an ‘app’ on your phone by dragging widget icons, I used a page full of sliders and you can easily customize the widgets. You select a WIFI com channel for each widget, the app sends the widget data to the uC. In the sketch you make a simple function for each com channel that assigns it to ANY variable. I think the refresh rate is as fast as your loop. Takes about 15 minutes to set up. You can also send any data from the uC to the app just as easily and display it with a variety of widgets. It’s free for a limited number of widgets.