OPM Parking Meters

#include <termios.h>

#include <fcntl.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <stdint.h>

#include <arpa/inet.h>

#include <netinet/in.h>

#include <netdb.h>

#define USE_SERVER

#define XBEE_PORT_DEFAULT "/dev/ttyUSB0" //or try USB1

#define XBEE_GET_PACKET_TIMEOUT 1000

#define XBEE_BUFFER_SIZE        128

#define SPOT_FREE  0

#define SPOT_TAKEN 1

static char* xbee_com_port = XBEE_PORT_DEFAULT;

static int xbee_stream;

char arrival_buf[XBEE_BUFFER_SIZE];

// location of last unread byte in buffer

volatile int buffer_last = 0;

// first unread byte in buffer

volatile int buffer_first = 0;

char *server_hostname;

char *ip_addr;

struct in_addr server_addr;

int  port;

int  socket_open();

static int xbee_read(char* buf, int size);

static void* listen_to_xbee();

int xbee_lib_init();

void wl_relay_update();

int main(int argc, char *argv[]) {

        if (argc != 3) {

        fprintf(stderr, "USAGE: %s <server_ip> <port>\n", argv[0]);

        exit(1);

    }

    // resolve server hostname

    server_hostname = argv[1];

    struct hostent *my_host = gethostbyname(server_hostname);

    if (my_host == NULL) {

        printf("Failed to resolve hostname\n");

    }

    memcpy(&server_addr, my_host->h_addr_list[0], sizeof(struct in_addr));

    ip_addr = inet_ntoa(server_addr);

    printf("%s -> %s\n", server_hostname, ip_addr);

    // port on server

    port = atoi(argv[2]);

    xbee_lib_init();

    while(1) {

            listen_to_xbee();

    }

        return 0;

}

int xbee_lib_init() {

        xbee_stream = open(xbee_com_port, O_RDWR);

        if (xbee_stream == -1) {

                printf("Failed to open connection to XBee on port ");

                printf("%i\n", *xbee_com_port);

                return -1;

        }

    else {

                  printf("Successfully opened connection to XBee on port ");

                printf("%i\n", (int)(*xbee_com_port));

        }

        // set baud rate, etc. correctly

        struct termios options;

        if(tcgetattr(xbee_stream, &options))

                printf("Error getting attributes");

        cfsetispeed(&options, B9600);

        cfsetospeed(&options, B9600);

        options.c_iflag &= ~ICRNL;

        options.c_oflag &= ~OCRNL;

        options.c_cflag |= (CLOCAL | CREAD);

        options.c_cflag &= ~PARENB;

        options.c_cflag &= ~CSTOPB;

        options.c_cflag &= ~CSIZE;

        options.c_cflag |= CS8;

        options.c_lflag &= ~ICANON;

        options.c_cc[VMIN] = 1;

        options.c_cc[VTIME] = 50;

        if (tcsetattr(xbee_stream, TCSANOW, &options)) {

                printf("Error setting attributes.\n");

                return -1;

        }

        return 0;

}

/**

 * Thread that listens to the xbee.

 **/

static void* listen_to_xbee() {

        char c;

        printf("Listening...\n");

        fflush(stdout);

    wl_relay_update();

    usleep(1000);

        return NULL;

}

static int xbee_read(char* buf, int size) {

        if (read(xbee_stream, buf, size) == -1) {

                printf("Failed to read from xbee.\r\n");

                return -1;

        }

        return 0;

}

void wl_relay_update() {

    // XBee API Mode Packet:

    // byte 0 = start delimiter (0x7E)

    // byte 1 = MSB of packet length (length of frame data)

    // byte 2 = LSB of packet length

    // byte 3 = API Identifier (0x81)

    // byte 4 = MSB of destination address

    // byte 5 = LSB of destination address

    // byte 6 = RSSI

    // byte 7 = Options (0x00)

    // byte 8 = Packet Type

    // byte 9 to n = RF Data (char*)

    //      9 = m_state

    //     10 = MSB of time_left

    //     11 = LSB of time_left

    //     12 = Button Status

    //     13 = Sonar Status

    // byte n+1 = checksum (add bytes 3 to n, subtract LSB from 0xFF)

    char     rec;

    uint16_t len;

    uint16_t src;

    uint8_t  rssi;

    uint8_t  m_state;

    uint16_t time_left;

    uint8_t  btn_status, sonar_status;

    uint8_t  checksum;

    int timeout_count = 0;

    // loop until we receive valid start byte

    xbee_read(&rec, 1);

    while (rec != 0x7E) {

        printf("Incorrect Start Delimiter\n");

        xbee_read(&rec, 1);

        timeout_count++;

        // try to reconnect to serial port:

        //  for when xbee is unplugged

        if (timeout_count > 500) {

            printf("are we unplugged?\n");

            timeout_count = 0;

            close(xbee_stream);

            xbee_lib_init();

        } 

    }

    xbee_read(&rec, 1);

    len = (uint8_t)rec << 8;

    xbee_read(&rec, 1);

    len |= (uint8_t)rec;

    char send_buf[len+4];

    send_buf[0] = 0x7E;

    send_buf[1] = ((uint8_t)len >> 8);

    send_buf[2] = (uint8_t)len;

    int i;

    for (i = 0; i <= len; i++) {

        xbee_read(&rec, 1);

        send_buf[i+3] = rec;

    }

    src = (send_buf[4] << 8) | send_buf[5];

    m_state = send_buf[9];

    time_left = ((uint8_t)send_buf[10] << 8) | (uint8_t)send_buf[11];

    //printf("len MSB: %x", (uint8_t)send_buf[10]);

    //printf(" len LSB: %x ", (uint8_t)send_buf[11]);

    btn_status = send_buf[12];

    sonar_status = send_buf[13];

    // sanity check - discard packet if it fails

    if ( (btn_status != 0 && btn_status != 1) ||

         (sonar_status != 0 && sonar_status != 1) ) {

        printf("bad packet from meter, not sent to server\n");

        return;

    }

    #ifdef USE_SERVER

    int sock = socket_open();

    //printf("sending to server\n");

    if (send(sock, send_buf, len+4, 0) != len+4) {

            printf("Mismatch in number of sent bytes");

            return;

    }

    close(sock);

    #endif

    printf("Meter %X is now ", src);

    if (m_state == SPOT_FREE) {

        printf("unoccupied. ");

    }

    else {

        printf ("occupied. ");

    }

    printf("There are %d seconds left. Button Status=%d. Sonar Status=%d\n",

           time_left, btn_status, sonar_status);

}

int socket_open() {

    int sock;

    struct sockaddr_in my_server;

    // Create the TCP socket

    if ((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) {

            printf("Failed to create socket\n");

            return -1;

    }

    // Construct the server sockaddr_in structure

    memset(&my_server, 0, sizeof(my_server));        // Clear struct

    my_server.sin_family = AF_INET;                  // Internet/IP

    my_server.sin_addr.s_addr = inet_addr(ip_addr);  // IP address

    my_server.sin_port = htons(port);                // server port

    // Establish connection

    if (connect(sock, (struct sockaddr *) &my_server, sizeof(my_server)) < 0) {

            printf("Failed to connect with server\n");

            return -1;

    }

    //printf("Socket created!?\n");

    return sock;

}