rxtest & txtest for CP2102N

rxtest.c

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

int main(int argc, const char *argv[])
{
  assert(argc == 2);

  while (1) {
    printf("Opening serial port %s for RX...\n", argv[1]);
    int fd = open (argv[1], O_RDWR | O_NOCTTY | O_SYNC);
    assert(fd >= 0);

    struct termios tty = { 0 };
    assert(tcgetattr (fd, &tty) == 0);

    cfsetospeed (&tty, B115200);
    cfsetispeed (&tty, B115200);

    tty.c_iflag &= ~(IGNBRK | BRKINT | ICRNL |
                     INLCR | PARMRK | INPCK | ISTRIP | IXON);
    tty.c_oflag = 0;
    tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);
    tty.c_cflag &= ~(CSIZE | PARENB | PARODD | CRTSCTS);
    tty.c_cflag |= CS8 | CLOCAL | CREAD;

    tty.c_cc[VMIN] = 1;
    tty.c_cc[VTIME] = 0;
    assert(tcsetattr (fd, TCSANOW, &tty) == 0);

    char buf[8+1] = { 0 };
    printf("Reading max %d bytes from port...\n", sizeof(buf)-1);
    int n = read(fd, buf, sizeof(buf)-1);
    printf("Read %d (%s)\n", n, buf);

    assert( tcflush(fd, TCIFLUSH) == 0 );
    close(fd);
    printf("Closed port @ %d.\n", (int)time(NULL));
  }
}

txtest.c

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

int main(int argc, const char *argv[])
{
  assert(argc == 2);
  printf("Opening serial port %s for TX...\n", argv[1]);
  int fd = open (argv[1], O_RDWR | O_NOCTTY | O_SYNC);
  assert(fd >= 0);

  struct termios tty = { 0 };
  assert(tcgetattr (fd, &tty) == 0);
  cfsetospeed (&tty, B115200);
  cfsetispeed (&tty, B115200);

  char buf[8];
  memset(buf, 'U', sizeof(buf));
  printf("Writing to port...\n");
  int r;
  do {
    r = write(fd, buf, sizeof(buf));
  } while(r >= 0);
}