C code to use a basic led strip. this example code should light 4 LEDs in order from Red, Green, Blue, White.

LEDstrip.c

#include <stdio.h>
#include <unistd.h>

//Green = DI
//Blue = CI
//BLack = GND
//Red = PWR


#define ledcount 4
char ledFrame[ledcount*4]; 

FILE * spidev;
void setled(int pixelIndex, unsigned char red, unsigned char green, unsigned char blue, unsigned char pixelIntensity);
void updateLEDs();

int main() {
    spidev = fopen("/dev/spidev1.0", "wb");
    for(int i = 0; i < ledcount; i++) {
        ledFrame[i*4] = 0xe0;
    }
    setled(0,100,0,0,5);
    setled(1,0,100,0,5);
    setled(2,0,0,100,5);
    setled(3,100,100,100,5);
    updateLEDs();
}

void setled(int pixelIndex, unsigned char red, unsigned char green, unsigned char blue, unsigned char pixelIntensity)
{
    pixelIntensity = 0xe0 | (pixelIntensity & 0x1f);
    
	int ledFrameIndex = pixelIndex * 4; // Positions index to beginning of each LED frame
	
    ledFrame[ledFrameIndex] = pixelIntensity;
    ledFrame[ledFrameIndex + 1] =  blue;
    ledFrame[ledFrameIndex + 2] =  green;
    ledFrame[ledFrameIndex + 3] =  red;
}

void updateLEDs()
{
	static const char startframe [4]={0,0,0,0};
	fwrite(startframe, 1, 4, spidev);
	fwrite(ledFrame, 1, ledcount*4, spidev);
	fflush(spidev);
}