C 10kHz

serialtimetest/serialtimetest.c

+//
+// serialtimetest.c
+//    serial speed time test
+//
+// Neil Gershenfeld  4/11/21
+// This work may be reproduced, modified, distributed,
+// performed, and displayed for any purpose, but must
+// acknowledge this project. Copyright is retained and
+// must be preserved. The work is provided as is; no
+// warranty is provided, and users accept all liability.
+//
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/time.h>
+#include <fcntl.h>
+#include <termios.h>
+#include <unistd.h>
+#include <stdlib.h>
+//
+int speed,port;
+unsigned char msg0 = 0;
+unsigned char msg1 = 255;
+//
+void timer_handler (int signum) {
+   static int flag = 0;
+   if (flag == 0) {
+      flag = 1;
+      write(port,&msg0,1);
+      }
+   else {
+      flag = 0;
+      write(port,&msg1,1);
+      }
+   }
+//
+int main(int argc,char *argv[]) {
+   if (argc != 3) {
+      printf("command line: serialtimetest port speed\n");
+      return -1;
+      }
+   //
+   speed = atoi(argv[2]);
+   port = open(argv[1],O_RDWR|O_NOCTTY|O_NDELAY);
+   fcntl(port,F_SETFL,0);
+   struct termios term;
+   tcgetattr(port,&term);
+   term.c_cflag &= ~(PARENB|CSTOPB|CSIZE|CRTSCTS);
+   term.c_cflag |= (CS8|CREAD|CLOCAL);
+   term.c_lflag &= ~(ICANON|ECHO|ECHOE|ECHONL|ISIG);
+   term.c_iflag &= ~(IXON|IXOFF|IXANY|IGNBRK|BRKINT
+      |PARMRK|ISTRIP|INLCR|IGNCR|ICRNL);
+   term.c_oflag &= ~(OPOST|ONLCR);
+   term.c_cc[VTIME] = 0;
+   term.c_cc[VMIN] = 1;
+   cfsetispeed(&term,speed);
+   cfsetospeed(&term,speed);
+   tcsetattr(port,TCSANOW,&term);
+   //
+   struct sigaction sa;
+   struct itimerval timer;
+   memset (&sa, 0, sizeof (sa));
+   sa.sa_handler = &timer_handler;
+   sigaction (SIGALRM, &sa, NULL);
+   timer.it_value.tv_sec = 0;
+   timer.it_value.tv_usec = 100;
+   timer.it_interval.tv_sec = 0;
+   timer.it_interval.tv_usec = 100;
+   setitimer (ITIMER_REAL,&timer,NULL);
+   //
+   while (1);
+   }