serialtest.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>

#define MAX_WEIGHT_BUFFER   1024
#define WEIGHT_TYPE_GROSS   1
#define WEIGHT_TYPE_TARE    2
#define TRUE    1
#define FALSE   0

int main() {
    int fd;
    char buf[14];
    int res=0;

    //printf("opening port...%s", "\n");
    fd=open("/dev/ttymxc0", O_RDWR|O_NOCTTY);

    if(fd==-1) {
        //printf("unable to open serial port%s", "\n");
        return -2;
    } else {
        tcflush(fd, TCIFLUSH);
        //printf("opened port%s", "\n");
        //printf("getting attr%s", "\n");
        struct termios oldtio,newtio;
        tcgetattr(fd,&oldtio);
        bzero(&newtio, sizeof(newtio));
        newtio.c_cflag = B9600|CS8|CREAD|CLOCAL;
        newtio.c_iflag = 0;
        newtio.c_oflag = 0;
        newtio.c_lflag = ICANON;
        newtio.c_cc[VINTR] = 0;
        newtio.c_cc[VQUIT] = 0;
        newtio.c_cc[VERASE] = 0;
        newtio.c_cc[VKILL] = 0;
        newtio.c_cc[VEOF] = 0;
        newtio.c_cc[VTIME] = 0;
        newtio.c_cc[VMIN] = 14;
        newtio.c_cc[VSWTC] = 0;
        newtio.c_cc[VSTART] = 0;
        newtio.c_cc[VSTOP] = 0;
        newtio.c_cc[VSUSP] = 0;
        newtio.c_cc[VEOL] = 10;
        newtio.c_cc[VREPRINT] = 0;
        newtio.c_cc[VDISCARD] = 0;
        newtio.c_cc[VWERASE] = 0;
        newtio.c_cc[VLNEXT] = 0;
        newtio.c_cc[VEOL2] = 0;
        //printf("flushing buffer%s", "\n");
        //tcflush(fd, TCIFLUSH);
        //printf("setting attr...%s", "\n");
        tcsetattr(fd, TCSAFLUSH, &newtio);
        //printf("attr set%s", "\n");
        /*
        struct termios options;
        tcgetattr(fd, &options);
        cfsetispeed(&options, B9600);
        cfsetospeed(&options, B9600);
        options.c_cflag |= (CLOCAL|CREAD);
        tcsetattr(fd, TCSANOW, &options);
        options.c_cflag &= ~CSIZE;
        options.c_cflag |= CS8;
        options.c_lflag &= ~(ICANON|ECHO|ECHOE|ISIG);
        options.c_oflag &= ~OPOST;
        options.c_cc[VMIN]=0;
        options.c_cc[VTIME]=10;
        */
    }
    //printf("connected, starting loop%s", "\n");
    //printf("flushing buffer%s", "\n");
    tcflush(fd, TCIOFLUSH);
    while(res!=14) {
        res=read(fd, buf, 14);
        buf[res]=0;
        //printf(":%s:%d\n",buf,res);
    }
    //'buf' now contains valid 14 characters of data
    int weight=0;
    int motion=FALSE;
    int weight_type=0;
    int negative=TRUE;

    //get the sign value
    if(buf[1]=='-') {
        negative=TRUE;
        //printf("negative weight%s", "\n");
    } else {
        negative=FALSE;
    }

    //get to the numeric characters
    int num_begin=0;
    while((buf[num_begin]-48)<0 || (buf[num_begin]-48)>9) {
        num_begin++;
    }

    //process numerical value
    while((buf[num_begin]-48)>=0 && (buf[num_begin]-48)<=9) {
        weight*=10;
        weight+=buf[num_begin]-48;
        num_begin++;
    }

    //printf("weight: %i%s", weight, "\n");

    //TODO: get unit type
    num_begin+=2;   //skipping "Lx" for now, will process later

    if(buf[num_begin]=='M') {
        motion=TRUE;
        //printf("motion found%s", "\n");
    }

    //build return string and send back to stdout
    char weight_buf[MAX_WEIGHT_BUFFER];
    char result[1024]="{\"motion\":";

    if(motion==FALSE) {
        strcat(result, "false,");
    } else {
        strcat(result, "true,");
    }
    strcat(result, "\"weight\":");
    if(negative==TRUE) {
        strcat(result, "-");
    }
    //itoa(weight, weight_buf, 10);
    sprintf(result, "%s%d", result, weight);
    //for(int i=0; i<MAX_WEIGHT_BUFFER; i++) {
    //  we
    //strcat(result, weight_buf);
    strcat(result, ",\"uom\":\"");
    strcat(result, "LBS");  //TODO: fill in the actual units here
    strcat(result, "\"}");
    printf("%s\n", result);

    return 0;
}