Detect button press inside a for() cycle

Question

I was working on a project with an LED strip, where I'd like to cycle through various effects with just a press of a button. The problem is that I don't know how to detect the press of the button to change effect while in for() cycling colors to have a rainbow effect (so it's a multitasking problem, I think). Could you help me? :)

#include <Adafruit_NeoPixel.h>
#define pin 5
#define led 15
#define button 7
Adafruit_NeoPixel strip = Adafruit_NeoPixel (led,pin,NEO_RGB+NEO_KHZ800);
int doggo=0;
void setup(){
 strip.begin();
 pinMode(button,INPUT);
}
void loop(){
 int buttonVal=digitalRead(button);
 if(buttonVal==HIGH){
 doggo++;
 delay(300);
 }
 if (doggo>2){
 doggo=0;
 }
 while (doggo==0){
 //whole strip red
 for (int i=0;i<led;i++){
 strip.setPixelColor(i,255,0,0);
 strip.show();
 }
 }
 while (doggo==1){
 //rainbow effect
 uint16_t i, j;
 int rainbowSpeed=10;
 for(j=0; j<256*5; j++) { 
 for(i=0; i< strip.numPixels(); i++) {
 strip.setPixelColor(i, Wheel(((i * 256 / strip.numPixels()) + j) & 255));
 strip.show();
 }
 }
 delay(rainbowSpeed);
 }
 while (doggo==2){
 //whole strip blue
 for (int i=0;i<led;i++){
 strip.setPixelColor(i,0,0,255);
 strip.show();
 }
 }
}
uint32_t Wheel(byte WheelPos) {
 WheelPos = 255 - WheelPos;
 if(WheelPos < 85) {
 return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
 }
 if(WheelPos < 170) {
 WheelPos -= 85;
 return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
 }
 WheelPos -= 170;
 return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}

Answer 1

You could use the Bounce2 library.

Call the update() method regularly and then check the state with read().

e.g.

for (...) {
 button.update();
 if (button.read() == HIGH) {
 //change pattern
 break;
 }
 // Do strip stuff.
}

As an added bonus the bounce library will debounce your button.

Answer 2

You should use a hardware interrupt. Depending on your microcontroller, you have different pins available.

Here is a reference for more details and syntax

• Lorenzo Alinari: Thanks, I correctly implemented the hardware interrupt since it works with single colors (there is no digitalRead in loop, just a attachInterrupt() in setup). Still, it doesn't work with the rainbow effect :(

Answer 3

I finally solved!

I tried the Bounce2 library, but it acted really strange (the effects passed from the first one, then the third one, then the first one again for a fraction of second and automatically to the second one, plus other things :/ )

It looks like I just needed to add a normal digitalRead inside for() and a return, I don't usually make those errors xD