improving gpio_write and verifying arguments

main.c

@@ -13,38 +13,41 @@
 // prototype functions
 int gpio_export(const char *gpio);
 int gpio_direction(const char *gpio, const char *direction); // this function
-int gpio_write(int gpio, int value);
+int gpio_write(const char *gpio, const char *value); // write function
+int gpio_read(const char *gpio); //read function
 
 int main(int argc, char *argv[]){
-
 	int fd;
-	const char *pin = argv[1]; // get gpio number from argument
+	const char *pin;
-	const char *dir = argv[2]; // get gpio direction from arguments
+	const char *dir;
-							   //
+	const char *val = NULL;
+	
+	// checking that at least gpio and direction is passed
+	if(argc<3){
+		printf("Usage:\n");
+		printf(" %s <gpio> in\n", argv[0]);
+		printf(" %s <gpio> out <value>\n", argv[0]);
+		return 1;
+	}
+	
+    pin = argv[1]; // get gpio number from argument
+	dir = argv[2]; // get gpio direction from arguments
+	
+	//const char *val = argv[3];
+	// checking the gpio direction
+	if(strcmp(dir, "out") == 0) {
+			if(argc<4){
+			printf("Error: GPIO out option requires a value.\n");
+			printf("Usage: %s <gpio> out <0|1>\n", argv[0]);
+			return 1;
+			}
+			val = argv[3];
+			}
+
 	gpio_export(pin); 
 	gpio_direction(pin, dir);
+	gpio_write(pin, val);
 	
-	
-	// pin value to 1
-	fd = open("/sys/class/gpio/chip0/gpio17/value", O_WRONLY);
-	if(fd<0)
-	{
-		perror("Error opening the GPIO path");
-		return -1;
-	}
-	write(fd,"1",1);
-	close(fd);
-	sleep(1);
-	// pin valu to 0
-	fd = open("/sys/class/gpio/chip0/gpio17/value", O_WRONLY);
-	if(fd<0)
-	{
-		perror("Error opening the GPIO path");
-		return -1;
-	}
-	write(fd,"0",1);
-	close(fd);
-	sleep(1);
 	// unexport
 	fd = open("/sys/class/gpio/chip0/unexport", O_WRONLY);
 	if(fd<0)
@@ -54,15 +57,6 @@ int main(int argc, char *argv[]){
 	}
 	write(fd,"17",2);
 	close(fd);
-
-
-	printf("Hello from Raspberry Pi!\n");
-	printf("Number of arguments: %d\n", argc);
-	printf("Program is reciving: %s\n", argv[0]);
-
-	if(argc > 1 )
-		printf("Argument: %s\n", argv[1]);
-	return 0;
 }
 
 // comple functions
@@ -100,11 +94,22 @@ int gpio_direction(const char *gpio, const char *direction){
 }
 
 
-
+int gpio_write(const char *gpio, const char *value){
-
+	int fd;
-
+	char path[64];
-
+	snprintf(path, sizeof(path),
-
+			"/sys/class/gpio/chip0/gpio%s/value", gpio);
-
+	fd = open(path, O_WRONLY);
-
+	if(fd<0){
-
+		perror("Error opening the GPIO path");
+		return -1;
+	}
+	if(write(fd,value, strlen(value)) < 0) {
+		perror("write");
+		close(fd);
+		return -1;
+	}
+	//write(fd, value, strlen(value));
+	close(fd);
+	return 0;
+}