Sending commands to Arduino while it's already running - c

Question

I'm currently making a robot and I'm using Raspberry pi 3 and Arduino uno for it.
What I want to do is send commands to Arduino via Pi by using a command line app (written in C)which takes in user input to make certain parts of the robot to move.

Answer 1

Use the following programs to send and receive serial data from Arduino:
Original Source
SEND.c
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define BAUDRATE B115200 //Baud Rate Here
#define MODEMDEVICE "/dev/ttyUSB0" //Serial Port Here
#define _POSIX_SOURCE 1 /* POSIX compliant source */
#define FALSE 0
#define TRUE 1
FILE *file;
int fileLen;
char *tmpbuffer;
void openport(void);
void readport(void);
void sendport(void);
int fd=0;
struct termios oldtp, newtp;
//char sendcmd1[256]="\0";
char buffer[512];
void main()
{
openport();
sleep(1);
// readport();
sendport();
}
void sendport(void)
{
printf("enter write\n");
int n;
// sem_wait(&len);
file = fopen("sample.txt", "r");
//get file size
fseek(file, 0, SEEK_END);
fileLen = ftell(file);
fseek(file, 0, SEEK_SET);
tmpbuffer = (char *)malloc(fileLen + 1);
//read file contents
printf("Start send\n");
fread(tmpbuffer, fileLen, 1, file);
fclose(file);
n = write(fd, tmpbuffer, fileLen + 1);
if (n < 0)
{
fputs("write() of bytes failed!\n", stderr);
}
else
{
printf("File sent successfully %d\n",n);
}
close(fd);
}
void openport(void)
{
fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY |O_NDELAY );
printf("Oviya %d\n",fd);
if (fd <0)
{
perror(MODEMDEVICE); }
fcntl(fd,F_SETFL,0);
tcgetattr(fd,&oldtp); /* save current serial port settings */
// tcgetattr(fd,&newtp); /* save current serial port settings */
bzero(&newtp, sizeof(newtp));
// bzero(&oldtp, sizeof(oldtp));
newtp.c_cflag = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD;
newtp.c_iflag = IGNPAR | ICRNL;
newtp.c_oflag = 0;
newtp.c_lflag = ICANON;
newtp.c_cc[VINTR] = 0; /* Ctrl-c */
newtp.c_cc[VQUIT] = 0; /* Ctrl-\ */
newtp.c_cc[VERASE] = 0; /* del */
newtp.c_cc[VKILL] = 0; /* # */
//newtp.c_cc[VEOF] = 4; /* Ctrl-d */
newtp.c_cc[VEOF] = 0; /* Ctrl-d */
newtp.c_cc[VTIME] = 0; /* inter-character timer unused */
newtp.c_cc[VMIN] = 1; /* blocking read until 1 character arrives */
newtp.c_cc[VSWTC] = 0; /* '\0' */
newtp.c_cc[VSTART] = 0; /* Ctrl-q */
newtp.c_cc[VSTOP] = 0; /* Ctrl-s */
newtp.c_cc[VSUSP] = 0; /* Ctrl-z */
newtp.c_cc[VEOL] = 0; /* '\0' */
newtp.c_cc[VREPRINT] = 0; /* Ctrl-r */
newtp.c_cc[VDISCARD] = 0; /* Ctrl-u */
newtp.c_cc[VWERASE] = 0; /* Ctrl-w */
newtp.c_cc[VLNEXT] = 0; /* Ctrl-v */
newtp.c_cc[VEOL2] = 0; /* '\0' */
// tcflush(fd, TCIFLUSH);
// tcsetattr(fd,TCSANOW,&newtp);
}
Go through the code and modify it according to your will.
This code expects a .txt file as input.
This answer is written from https://www.codeproject.com/Questions/718340/C-program-to-Linux-Serial-port-read-write
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