====Welcome====

====Purpose====
The purpose of this project was to create a simple daemon type utility that checks the state of a MYSQL database. Based on the state of certain data the program will execute certain operations.

====The GPIO====
Using the wringPi library means you can use your RPi's GPIO like an Arduino's. This means easy access to the GPIO in C/C++ programs.

the workhorse of wiringPi is: "pinMode(pinNumber, OUTPUT/INPUT);" and "digitalWrite(pinNumber, state);"

====PHP and MYSQL====
Using a PHP frontend and MYSQL as mediator we can have users interface with the RPi's GPIO via a web GUI. Let's abstract that away for now and focus on the daemon.

====C code====
Here's some code that establishes a local MYSQL connection and checks the database based on an interval of seconds chosen as an initial argument.

<code c>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <wiringPi.h>
#include </usr/include/mysql/mysql.h>

int main(int argc, char *argv[]){
char user[7] = "gpio";
char pass[6] = "*****";

MYSQL *connection;
MYSQL_RES *result;
MYSQL_ROW row;
int num_fields;
int i;

if (wiringPiSetup () == -1)
    exit (1) ;


connection = mysql_init(NULL);
if (connection == NULL) {
      printf("Error %u: %s\n", mysql_errno(connection), mysql_error(connection));
      exit(1);
}else{
printf("connection established\n");
}

printf("MySQL client version: %s\n", mysql_get_client_info());

mysql_real_connect(connection, "localhost", user, pass, "gpio", 0, NULL, 0);
int repeatFlag = atoi(argv[1]);
char test[4];
for(;;){

	mysql_query(connection, "SELECT pinDirection FROM pinDirection WHERE pinNumber ='17'");
	result = mysql_store_result(connection);
	num_fields = mysql_num_fields(result);
	while ((row = mysql_fetch_row(result)))
  	{
      		for(i = 0; i < num_fields; i++)
      		{
			char* tester = row[i] ? row[i] : "NULL";
			if (tester[0] == 'o' && tester[1] == 'u' && tester[2] == 't'){
				printf("%s\n",tester);
				pinMode(0, OUTPUT);
				mysql_query(connection, "SELECT pinStatus FROM pinStatus WHERE pinNumber ='17'");
				result = mysql_store_result(connection);
			        num_fields = mysql_num_fields(result);
				tester = NULL;
				while ((row = mysql_fetch_row(result))){
					for(i = 0; i < num_fields; i++){
						char *tester = row[i] ? row[i] : "NULL";
						printf("State: %s\n",tester);
						if (tester[0] == '0'){
							digitalWrite(0, 0);
						}else digitalWrite(0, 1);
					}
				}
			}else if(tester[0] == 'i' && tester[1] == 'n'){
				printf("%s\n",tester);
				pinMode(0, INPUT);
				mysql_query(connection, "SELECT pinStatus FROM pinStatus WHERE pinNumber ='17'");
                                result = mysql_store_result(connection);
                                num_fields = mysql_num_fields(result);
				tester = NULL;
                                while ((row = mysql_fetch_row(result))){
                                        for(i = 0; i < num_fields; i++){
                                        	char *tester = row[i] ? row[i] : "NULL";
                                                printf("State%s\n",tester);
                                                if (tester[0] == '0'){
                                                        digitalWrite(0, 0);
                                                }else digitalWrite(0, 1);
                                        }
                                }
			}
      		}
      		printf("\n");
  	}
	sleep(repeatFlag);
}




mysql_free_result(result);
mysql_close(connection);


return 0;
}
</code>