arduino-thermometer/main.c

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <stdlib.h>
#include <signal.h>
#include <time.h>

#include <sqlite3.h>
#include <stdbool.h>

#define WTHR_STATION_ID 0
#define TIMESTAMP_FIELD 1
#define DATA_VAL_FIELD 2
#define STATION_ID_FIELD 3
#define INSERT_HUM_TEMPL "INSERT INTO humidity(timestamp, value, station) VALUES(?, ?, ?)"
#define INSERT_TEMP_TEMPL "INSERT INTO temperature(timestamp, value, station) VALUES(?, ?, ?)"

sqlite3* get_db(void) {
   sqlite3 *db;
   char *zErrMsg = 0;
   int rc;

   rc = sqlite3_open("test.db", &db);

   if( rc ) {
      fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
   } else {
      fprintf(stderr, "Opened database successfully\n");
   }

   return db;
}

int open_port(void) {
    int fd; /* File descriptor for the port */

    fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1) {
        perror("open_port: Unable to open /dev/USB0 - ");
    } else
        fcntl(fd, F_SETFL, 0);
    return (fd);
}

enum record_type {
    R_TEMP,
    R_REL_HUMIDITY
};

void ccleanup(sqlite3 *db) {
    static bool setup = false;
    static sqlite3 *saved;

    if (!setup) {
        saved = db;
        setup = true;
    } else {
        sqlite3_close(db);
        printf("Closed DB.\n");
    }

}

static void call_cleanup(int signo) {
    ccleanup(NULL);
    exit(0);
}

struct query_result {
    int argc;
    char **argv;
    char **azColName;
};

static int save_qry(void *retval, int argc, char **argv, char **azColName) {
    struct query_result r;
    r.argc = argc;
    r.argv = argv;
    r.azColName = azColName;

    struct query_result* ret  = retval;
    *ret = r;

    return 0;
}

static int callback(void *retval, int argc, char **argv, char **azColName) {
    int i;
    for(i = 0; i<argc; i++) {
      printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");
    }
    printf("\n");
    return 0;
}

void initialise_db(sqlite3* db) {
    char *query = "SELECT name from sqlite_master WHERE name = 'temperature'";
    char *zErrMsg = 0;
    int rc;
    struct query_result r;

    rc = sqlite3_exec(db, query, save_qry, &r, &zErrMsg);

    if (rc != SQLITE_OK) {
        fprintf(stderr, "SQL: %s\n", zErrMsg);
        sqlite3_free(zErrMsg);
    }

    if (r.argc == 0) {
        char *query = "CREATE TABLE temperature (" \
            "timestamp INT PRIMARY KEY NOT NULL," \
            "value INT NOT NULL," \
            "station INT NOT NULL," \
            "FOREIGN KEY(station) REFERENCES station(id)" \
               " )";
        rc = sqlite3_exec(db, query, save_qry, &r, &zErrMsg);
        if (rc != SQLITE_OK) {
            fprintf(stderr, "SQL: %s\n", zErrMsg);
            sqlite3_free(zErrMsg);
            call_cleanup(1);
        }
    }
    query = "SELECT name from sqlite_master WHERE name = 'humidity'";

    struct query_result re;
    rc = sqlite3_exec(db, query, save_qry, &re, &zErrMsg);

    if (rc != SQLITE_OK) {
        fprintf(stderr, "SQL: %s\n", zErrMsg);
        sqlite3_free(zErrMsg);
        call_cleanup(1);
    }

    if (re.argc == 0) {
        query = "CREATE TABLE humidity(" \
            "timestamp INT PRIMARY KEY NOT NULL," \
            "value INT NOT NULL," \
            "station INT NOT NULL," \
            "FOREIGN KEY(station) REFERENCES station(id)" \
               " )";
        rc = sqlite3_exec(db, query, save_qry, &r, &zErrMsg);
        if (rc != SQLITE_OK) {
            fprintf(stderr, "SQL: %s\n", zErrMsg);
            sqlite3_free(zErrMsg);
            call_cleanup(1);
        }
    }
}

int check_error(int rc) {
    if (rc != SQLITE_OK) {
        fprintf(stderr, "SQL Error: %d\n", rc);
        call_cleanup(1);
    }
    return 0;
}

int insert_rec(sqlite3 *db, char* sqlt, int value, int station, int timestamp) {
    sqlite3_stmt * statement;
    const char *tail = 0;
    int rc = sqlite3_prepare_v2(db, sqlt, -1, &statement,  &tail); 
    check_error(rc);
    rc = sqlite3_bind_int(statement, DATA_VAL_FIELD, value);
    check_error(rc);
    rc = sqlite3_bind_int(statement, STATION_ID_FIELD, station);
    check_error(rc);
    rc = sqlite3_bind_int(statement, TIMESTAMP_FIELD, timestamp);
    check_error(rc);
    rc = sqlite3_step(statement);
    if (rc != SQLITE_DONE) {
        check_error(rc);
    }
    rc = sqlite3_finalize(statement);
    check_error(rc);
    return 0;
}

int main (int argc, char **arv) {
    sqlite3 *db = get_db();
    ccleanup(db);
    initialise_db(db);

    signal(SIGINT, call_cleanup);

    FILE *serial = fdopen(open_port(), "r");

    char string[200];
    int val;

    int time_now = 0;
    int last_time = 0;
    while(1) {
        last_time = time_now;
        time_now = time(NULL);
        memset(string, 0, sizeof(char) * 200);
        fscanf(serial, "%s%d", string, &val);
        if (!strcmp(string, "temp:")) {
            printf("Temperature: %d\n", val);
            if (last_time != time_now) {
                insert_rec(db, INSERT_TEMP_TEMPL, val, WTHR_STATION_ID, time_now);
            }
        }
        if (!strcmp(string, "humi:")) {
            printf("Relative Humidity: %d\n", val);
            if (last_time != time_now) {
                insert_rec(db, INSERT_HUM_TEMPL, val, WTHR_STATION_ID, time_now);
            }
        }
    }

    fclose(serial);
}