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I recently switched over to Visual studio code and away from the arduino IDE though I am a novice at both. When using VSC and the neopixel library and sample code(strandtest) containing animations such as color wipe, I run into declaration errors. I have insalled the library to the project im working on, it is declared by default in the platformio.ini file as expected. The animation function is in the code as well and the same code works just fine in the Arduino IDE as stated. The standard example files (ie ones other than strand test with no declared function animations) work just fine no declaration issues. When I compile in the arduino ide it works as expected can use the example and immediately upload it no problem.

#include <Arduino.h>

// A basic everyday NeoPixel strip test program.

// NEOPIXEL BEST PRACTICES for most reliable operation:
// - Add 1000 uF CAPACITOR between NeoPixel strip's + and - connections.
// - MINIMIZE WIRING LENGTH between microcontroller board and first pixel.
// - NeoPixel strip's DATA-IN should pass through a 300-500 OHM RESISTOR.
// - AVOID connecting NeoPixels on a LIVE CIRCUIT. If you must, ALWAYS
//   connect GROUND (-) first, then +, then data.
// - When using a 3.3V microcontroller with a 5V-powered NeoPixel strip,
//   a LOGIC-LEVEL CONVERTER on the data line is STRONGLY RECOMMENDED.
// (Skipping these may work OK on your workbench but can fail in the field)

#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
 #include <avr/power.h> // Required for 16 MHz Adafruit Trinket
#endif

// Which pin on the Arduino is connected to the NeoPixels?
// On a Trinket or Gemma we suggest changing this to 1:
#define LED_PIN    3

// How many NeoPixels are attached to the Arduino?
#define LED_COUNT 4

// Declare our NeoPixel strip object:
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
// Argument 1 = Number of pixels in NeoPixel strip
// Argument 2 = Arduino pin number (most are valid)
// Argument 3 = Pixel type flags, add together as needed:
//   NEO_KHZ800  800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)
//   NEO_KHZ400  400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)
//   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)
//   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
//   NEO_RGBW    Pixels are wired for RGBW bitstream (NeoPixel RGBW products)


// setup() function -- runs once at startup --------------------------------

void setup() {
  // These lines are specifically to support the Adafruit Trinket 5V 16 MHz.
  // Any other board, you can remove this part (but no harm leaving it):
#if defined(__AVR_ATtiny85__) && (F_CPU == 16000000)
  clock_prescale_set(clock_div_1);
#endif
  // END of Trinket-specific code.

  strip.begin();           // INITIALIZE NeoPixel strip object (REQUIRED)
  strip.show();            // Turn OFF all pixels ASAP
  strip.setBrightness(50); // Set BRIGHTNESS to about 1/5 (max = 255)
}


// loop() function -- runs repeatedly as long as board is on ---------------

void loop() {
  // Fill along the length of the strip in various colors...
  colorWipe(strip.Color(255,   0,   0), 50); // Red
  colorWipe(strip.Color(  0, 255,   0), 50); // Green
  colorWipe(strip.Color(  0,   0, 255), 50); // Blue

  // Do a theater marquee effect in various colors...
  theaterChase(strip.Color(127, 127, 127), 50); // White, half brightness
  theaterChase(strip.Color(127,   0,   0), 50); // Red, half brightness
  theaterChase(strip.Color(  0,   0, 127), 50); // Blue, half brightness

  rainbow(10);             // Flowing rainbow cycle along the whole strip
  theaterChaseRainbow(50); // Rainbow-enhanced theaterChase variant
}


// Some functions of our own for creating animated effects -----------------

// Fill strip pixels one after another with a color. Strip is NOT cleared
// first; anything there will be covered pixel by pixel. Pass in color
// (as a single 'packed' 32-bit value, which you can get by calling
// strip.Color(red, green, blue) as shown in the loop() function above),
// and a delay time (in milliseconds) between pixels.
void colorWipe(uint32_t color, int wait) {
  for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...
    strip.setPixelColor(i, color);         //  Set pixel's color (in RAM)
    strip.show();                          //  Update strip to match
    delay(wait);                           //  Pause for a moment
  }
}

// Theater-marquee-style chasing lights. Pass in a color (32-bit value,
// a la strip.Color(r,g,b) as mentioned above), and a delay time (in ms)
// between frames.
void theaterChase(uint32_t color, int wait) {
  for(int a=0; a<10; a++) {  // Repeat 10 times...
    for(int b=0; b<3; b++) { //  'b' counts from 0 to 2...
      strip.clear();         //   Set all pixels in RAM to 0 (off)
      // 'c' counts up from 'b' to end of strip in steps of 3...
      for(int c=b; c<strip.numPixels(); c += 3) {
        strip.setPixelColor(c, color); // Set pixel 'c' to value 'color'
      }
      strip.show(); // Update strip with new contents
      delay(wait);  // Pause for a moment
    }
  }
}

// Rainbow cycle along whole strip. Pass delay time (in ms) between frames.
void rainbow(int wait) {
  // Hue of first pixel runs 5 complete loops through the color wheel.
  // Color wheel has a range of 65536 but it's OK if we roll over, so
  // just count from 0 to 5*65536. Adding 256 to firstPixelHue each time
  // means we'll make 5*65536/256 = 1280 passes through this outer loop:
  for(long firstPixelHue = 0; firstPixelHue < 5*65536; firstPixelHue += 256) {
    for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...
      // Offset pixel hue by an amount to make one full revolution of the
      // color wheel (range of 65536) along the length of the strip
      // (strip.numPixels() steps):
      int pixelHue = firstPixelHue + (i * 65536L / strip.numPixels());
      // strip.ColorHSV() can take 1 or 3 arguments: a hue (0 to 65535) or
      // optionally add saturation and value (brightness) (each 0 to 255).
      // Here we're using just the single-argument hue variant. The result
      // is passed through strip.gamma32() to provide 'truer' colors
      // before assigning to each pixel:
      strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(pixelHue)));
    }
    strip.show(); // Update strip with new contents
    delay(wait);  // Pause for a moment
  }
}

// Rainbow-enhanced theater marquee. Pass delay time (in ms) between frames.
void theaterChaseRainbow(int wait) {
  int firstPixelHue = 0;     // First pixel starts at red (hue 0)
  for(int a=0; a<30; a++) {  // Repeat 30 times...
    for(int b=0; b<3; b++) { //  'b' counts from 0 to 2...
      strip.clear();         //   Set all pixels in RAM to 0 (off)
      // 'c' counts up from 'b' to end of strip in increments of 3...
      for(int c=b; c<strip.numPixels(); c += 3) {
        // hue of pixel 'c' is offset by an amount to make one full
        // revolution of the color wheel (range 65536) along the length
        // of the strip (strip.numPixels() steps):
        int      hue   = firstPixelHue + c * 65536L / strip.numPixels();
        uint32_t color = strip.gamma32(strip.ColorHSV(hue)); // hue -> RGB
        strip.setPixelColor(c, color); // Set pixel 'c' to value 'color'
      }
      strip.show();                // Update strip with new contents
      delay(wait);                 // Pause for a moment
      firstPixelHue += 65536 / 90; // One cycle of color wheel over 90 frames
    }
  }
}

The error I run into when compiling is as follows.

> Executing task in folder led pir: C:\Users\Yeee\.platformio\penv\Scripts\pio.exe run --target upload <

Processing nanoatmega328new (platform: atmelavr; board: nanoatmega328new; framework: arduino)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/atmelavr/nanoatmega328new.html
PLATFORM: Atmel AVR (3.1.0) > Arduino Nano ATmega328 (New Bootloader)
HARDWARE: ATMEGA328P 16MHz, 2KB RAM, 30KB Flash
DEBUG: Current (avr-stub) On-board (avr-stub, simavr)
PACKAGES:
 - framework-arduino-avr 5.1.0
 - tool-avrdude 1.60300.200527 (6.3.0)
 - toolchain-atmelavr 1.50400.190710 (5.4.0)
LDF: Library Dependency Finder -> https://docs.platformio.org/en/latest/librarymanager/ldf.html
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 7 compatible libraries
Scanning dependencies...
Dependency Graph
|-- <Adafruit NeoPixel> 1.7.0
Building in release mode
Compiling .pio\build\nanoatmega328new\src\main.cpp.o
src\main.cpp: In function 'void loop()':
src\main.cpp:59:43: error: 'colorWipe' was not declared in this scope
   colorWipe(strip.Color(255,   0,   0), 50); // Red
                                           ^
src\main.cpp:64:46: error: 'theaterChase' was not declared in this scope
   theaterChase(strip.Color(127, 127, 127), 50); // White, half brightness
                                              ^
src\main.cpp:68:13: error: 'rainbow' was not declared in this scope
   rainbow(10);             // Flowing rainbow cycle along the whole strip
             ^
src\main.cpp:69:25: error: 'theaterChaseRainbow' was not declared in this scope
   theaterChaseRainbow(50); // Rainbow-enhanced theaterChase variant
                         ^
src\main.cpp: In function 'void colorWipe(uint32_t, int)':
src\main.cpp:81:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...
                 ^
src\main.cpp: In function 'void theaterChase(uint32_t, int)':
src\main.cpp:96:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       for(int c=b; c<strip.numPixels(); c += 3) {
                     ^
src\main.cpp: In function 'void rainbow(int)':
src\main.cpp:112:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...
                   ^
src\main.cpp: In function 'void theaterChaseRainbow(int)':
src\main.cpp:136:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       for(int c=b; c<strip.numPixels(); c += 3) {
                     ^
*** [.pio\build\nanoatmega328new\src\main.cpp.o] Error 1
================================================================================== [FAILED] Took 1.30 seconds ==================================================================================
The terminal process "C:\Users\Yeee\.platformio\penv\Scripts\pio.exe 'run', '--target', 'upload'" terminated with exit code: 1.

Terminal will be reused by tasks, press any key to close it.
3
  • add forward declarations of functions. in Arduino IDE the builder does it for you at ino to cpp conversion – Juraj Mar 2 at 5:35
  • @Juraj, if you make that an answer, I'll vote it up, because it points out something relevant to using the Arduino core and libraries with their build environment. IMO, to be a valid answer it needn't necessarily explain the required C++ aspects, however helpful that might be. That this is apparently just part of the trade made in choosing to use platform.io, assuming it isn't also capable of running arduino-cli/arduino-builder. – timemage Mar 2 at 15:29
  • To the extent possible, you can also just arrange your function definitions to appear before their usages. The definition will serve as a declaration. If you don't have any mutually recursive functions this is generally something you can do within the context of a single file. – timemage Mar 2 at 15:39

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