I was modifying my all dancing, all singing neopixel libraries to add support for WS2812Serial. In looking at the header file, I noticed there was a busy function that returned a bool. I assumed this would allow me to poll whether the previous request had finished (assuming that show would be non-blocking).

But it looks like there is a busy function in the header file, there is no busy function in the C++ file.

Here is the BasicTest example with a busy test added:

Code:
/* WS2812Serial BasicTest Example

   Test LEDs by turning then 7 different colors.

   This example code is in the public domain. */

#include <WS2812Serial.h>

const int numled = 64;
const int pin = 1;

// Usable pins:
//   Teensy LC:   1, 4, 5, 24
//   Teensy 3.2:  1, 5, 8, 10, 31   (overclock to 120 MHz for pin 8)
//   Teensy 3.5:  1, 5, 8, 10, 26, 32, 33, 48
//   Teensy 3.6:  1, 5, 8, 10, 26, 32, 33
//   Teensy 4.0:  1, 8, 14, 17, 20, 24, 29, 39
//   Teensy 4.1:  1, 8, 14, 17, 20, 24, 29, 35, 47, 53

byte drawingMemory[numled*3];         //  3 bytes per LED
DMAMEM byte displayMemory[numled*12]; // 12 bytes per LED

WS2812Serial leds(numled, displayMemory, drawingMemory, pin, WS2812_GRB);

#define RED    0xFF0000
#define GREEN  0x00FF00
#define BLUE   0x0000FF
#define YELLOW 0xFFFF00
#define PINK   0xFF1088
#define ORANGE 0xE05800
#define WHITE  0xFFFFFF

// Less intense...
/*
#define RED    0x160000
#define GREEN  0x001600
#define BLUE   0x000016
#define YELLOW 0x101400
#define PINK   0x120009
#define ORANGE 0x100400
#define WHITE  0x101010
*/

void setup() {
  leds.begin();
}

void loop() {
  // change all the LEDs in 1.5 seconds
  int microsec = 1500000 / leds.numPixels();

  colorWipe(RED, microsec);
  colorWipe(GREEN, microsec);
  colorWipe(BLUE, microsec);
  colorWipe(YELLOW, microsec);
  colorWipe(PINK, microsec);
  colorWipe(ORANGE, microsec);
  colorWipe(WHITE, microsec);
}

void colorWipe(int color, int wait) {
  for (int i=0; i < leds.numPixels(); i++) {
    leds.setPixel(i, color);
    leds.show();
    delayMicroseconds(wait);
    while (leds.busy ()) {
      yield ();
    }
  }
}
And here is the error message I got with Teensydunio 1.57 using the Arduino 1.8.19 libraries on a Fedora 36 x86_64 system:

Code:
/tmp/arduino_build_245626/sketch/Ws2812Serial_test.ino.cpp.o: In function `colorWipe(int, int)':
/home/meissner/Arduino/Tests/NeoPixel/Ws2812Serial_test/Ws2812Serial_test.ino:66: undefined reference to `WS2812Serial::busy()'
/home/meissner/Arduino/Tests/NeoPixel/Ws2812Serial_test/Ws2812Serial_test.ino:66: undefined reference to `WS2812Serial::busy()'
collect2: error: ld returned 1 exit status
Error compiling for board Teensy 4.1.