L5-LEDC/main.c

// LED application in C by
// Gerado Marx Chavez Campos, 26/04/2021
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

#define LED3PATH "/sys/class/leds/beaglebone:green:usr3"
#define bon "/brightness"
#define trg "/trigger"

//Function prototypes
void WriteLED(char fileName[], char value[]);
void RemoveTrigger();

//main
int main(int argc, char* argv[]){
	if(argc!=2){
		printf("Incorrect use of command...\n");
		printf("Please use LEDc with:\n");
		printf("on, off, flash or status.\n");
		printf("\n");
		printf("Example: LEDc on\n");
		return 2;
	}
	printf("Starting Application...\n");
	//checking the command argument:
	if(strcmp(argv[1], "on")==0){
		printf("Turning LED on\n");
		RemoveTrigger();
		WriteLED(bon,"1");
	}
	else if(strcmp(argv[1], "off")==0){
		printf("Turning LED off\n");
		RemoveTrigger();
		WriteLED(bon,"0");
	}
printf("LED Application Done\n");
return 0;
}

//complete functions here:
void WriteLED(char filename[], char value[]){
	FILE* fp; //file pointer
	char fileName[100]; //var to store path and file
	sprintf(fileName, LED3PATH "%s", filename);
	fp = fopen(fileName, "w+");
	fprintf(fp, "%s", value);
	fclose(fp);
}
void RemoveTrigger(){
	WriteLED(trg, "none");
}