Hello All About Circuits forum

Have put together a simple circuit that operates
an LED strip, WS2812b using a microcontoller
XIAO SAMD21
SAMD21_to_WS2812b_schematic_250721.jpg

The sketch on the SAMD21 is
WS2812b_Fade_Color_to_Color_250722.ino

//from
//https://arduino.stackexchange.com/questions/13136/fading-colors-on-a-ws2812-strip

#include <FastLED.h>
#define DATA_PIN 4
#define NUM_LEDS 299

#define COLOR_ORDER GRB

CRGB leds[NUM_LEDS];

void setup(){
  FastLED.addLeds<WS2811, DATA_PIN, GRB>(leds, NUM_LEDS);
}

void loop(){

  // 256 steps to get from blue to red
  // (the most possible with an LED with 8 bit RGB values)

  for( int colorStep=0; colorStep<256; colorStep++ ) {

      int r = colorStep;  // Redness starts at zero and goes up to full
      int b = 255-colorStep;  // Blue starts at full and goes down to zero
      int g = 0;              // No green needed to go from blue to red

      // Now loop though each of the LEDs and set each one to the current color

      for(int x = 0; x < NUM_LEDS; x++){
          leds[x] = CRGB(r,g,b);
       }

      // Display the colors we just set on the actual LEDs
      FastLED.show();

      delay(10);
  }

}

Would like to turn on the strip with
PIR (motion detector).

This is the schematic for a simple
PIR circuit.

This the sketch for the simple PIR circuit.

//from
//https://circuitdigest.com/microcontroller-projects/arduino-motion-detector-using-pir-sensor
// this sketch works with schematic /PIR_to_Arduino_250725/PIR_to_SAMD21_to_LED_250725.jpg

void setup() {
  pinMode(2, INPUT); //Pin 2 as INPUT
  pinMode(3, OUTPUT); //PIN 3 as OUTPUT
}
void loop() {
  if (digitalRead(2) == HIGH)
  {
  digitalWrite(3, HIGH);   // turn the LED
  delay(1000);                       // wait for 100 msecond
  digitalWrite(3, LOW);   // turn the LED off
  delay(100);                       // wait for 100 msecond
  }
}

This is the schematic which adds the
PIR to the SAMD21 to WS28212b circuit


Combined the PIR logic with the
WS28212b code in sketch
PIR_to_SAMD21_to_WS28212b_250725.ino

/* ************************************
PIR_to_SAMD21_to_WS28212b_250725.ino
combines
PIR sensor code from
PIR_to_Arduino_250725.ino
with PIR digitalRead code from
Staircase_Single_Channel_PIR_to_LED_220424.ino
with WS28212b code from
WS2812b_Fade_Color_to_Color_250722.ino

************************************ */

#include <FastLED.h>
#define DATA_PIN 4
#define NUM_LEDS 30

#define COLOR_ORDER GRB

void setup() {
   FastLED.addLeds<WS2811, DATA_PIN, GRB>(leds, NUM_LEDS);
   pinMode(2, INPUT); //Pin 2 as INPUT
}

void loop() {
  if (digitalRead(2) == HIGH)
  runSAMD21()
 }   

void runSAMD21(){

  // 256 steps to get from blue to red
  // (the most possible with an LED with 8 bit RGB values)

  for( int colorStep=0; colorStep<256; colorStep++ ) {

      int r = colorStep;  // Redness starts at zero and goes up to full
      int b = 255-colorStep;  // Blue starts at full and goes down to zero
      int g = 0;              // No green needed to go from blue to red

      // Now loop though each of the LEDs and set each one to the current color

      for(int x = 0; x < NUM_LEDS; x++){
          leds[x] = CRGB(r,g,b);
          
      }

      // Display the colors we just set on the actual LEDs
      FastLED.show();

      delay(10);
  }

}

The WS28212b code is
in a function runSAMD21() which is
called by void loop().
PIR_to_SAMD21_to_WS28212b_250725.ino

When the sketch is compiled the IDE
returns
Compilation error: 'leds' was not declared in this scope
at the line
FastLED.addLeds<WS2811, DATA_PIN, GRB>(leds, NUM_LEDS);

Which is surprising because the sketch
WS2812b_Fade_Color_to_Color_250722.ino
has the same line and compiles ok.

It is surmised that 'leds' is found in
the FastLED.h library so does not have to be
defined in WS2812b_Fade_Color_to_Color_250722.ino

But the FastLED.h library is also called by
PIR_to_SAMD21_to_WS28212b_250725.ino
so why does the sketch
WS2812b_Fade_Color_to_Color_250722.ino
compile and the sketch
PIR_to_SAMD21_to_WS28212b_250725.ino
return a compilation error?

Thanks.

Allen Pitts

 

CRGB leds[NUM_LEDS];

is missing in PIR_to_SAMD21_to_WS28212b_250725.ino

 

https://github.com/fastled/fastled/wiki/basic-usage