rp2040

RP2040 Programming without SDK
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cons.c (2691B)

      1 #include <errno.h>
      2 #include <fcntl.h>
      3 #include <stdio.h>
      4 #include <stdlib.h>
      5 #include <string.h>
      6 #include <sys/ioctl.h>
      7 #include <sys/termios.h>
      8 #include <sys/wait.h>
      9 #include <unistd.h>
     10 
     11 int device_open();
     12 int setparms(int fd, int baud);
     13 int flush(int fd);
     14 
     15 #define ERRLEN 128
     16 char err[ERRLEN];
     17 #define BUFSIZE 16
     18 
     19 int
     20 main(void)
     21 {
     22 	int fd;
     23 	int ret = 0;
     24 	int cret;
     25 	struct termios *term;
     26 	
     27 	fd = device_open();
     28 	if (fd < 0) {
     29 		fprintf(stderr, "can't open device: %s\n", strerror(errno));
     30 		return 1;
     31 	}
     32 	if (setparms(fd, 115200) < 0) {
     33 		fprintf(stderr, "setparm: %s\n", err);
     34 		return 1;
     35 	}
     36 
     37 	if (flush(fd) < 0) {
     38 		fprintf(stderr, "flush: %s\n", strerror(errno));
     39 		ret = errno;
     40 		goto defer;
     41 	}
     42 
     43 	if (fork() == 0) {
     44 		int n;
     45 		char buf[BUFSIZE];
     46 		int ret = 0;
     47 		for (;;) {
     48 			n = read(0, buf, BUFSIZE);
     49 			if (n == 0) {
     50 				fprintf(stderr, "eof\n");
     51 				break;
     52 			} else if (n < 0) {
     53 				fprintf(stderr, "read stdin: %s\n", strerror(errno));
     54 				ret = 1;
     55 				break;
     56 			}
     57 			n = write(fd, buf, n);
     58 			if (n < 0) {
     59 				fprintf(stderr, "write to tty %s\n", strerror(errno));
     60 				ret = 1;
     61 				break;
     62 			}
     63 		}
     64 		_exit(ret);
     65 	}
     66 	if (fork() == 0) {
     67 		int n;
     68 		char buf[BUFSIZE];
     69 		int ret = 0;
     70 		for (;;) {
     71 			n = read(fd, buf, BUFSIZE);
     72 			if (n < 0) {
     73 				fprintf(stderr, "read tty: %s\n", strerror(errno));
     74 				ret = 1;
     75 				break;
     76 			}
     77 			n = write(1, buf, n);
     78 			if (n < 0) {
     79 				fprintf(stderr, "write to stdout %s\n", strerror(errno));
     80 				ret = 1;
     81 				break;
     82 			}
     83 		}
     84 		_exit(ret);
     85 	}
     86 
     87 	wait(&cret);
     88 defer:
     89 	close(fd);
     90 	if (ret == 0) {
     91 		ret = cret;
     92 	}
     93 	return ret;
     94 		int n;
     95 }
     96 
     97 int
     98 device_open()
     99 {
    100 	int n;
    101 	int fd;
    102 
    103 	fd = open("/dev/ttyU0", O_RDWR|O_NDELAY|O_NOCTTY);
    104 	if (fd < 0)
    105 		return -1;
    106 	n = fcntl(fd, F_GETFL, 0);
    107 	fcntl(fd, F_SETFL, n&~O_NDELAY);
    108 	return fd;
    109 }
    110 
    111 int
    112 setparms(int fd, int baud)
    113 {
    114 	struct termios tty;
    115 	if (tcgetattr(fd, &tty) < 0) {
    116 		snprintf(err, ERRLEN, "tcgetattr: %s", strerror(errno));
    117 		return -1;
    118 	}
    119 	if (cfsetospeed(&tty, (speed_t)baud) < 0) {
    120 		snprintf(err, ERRLEN, "cfsetospeed: %s", strerror(errno));
    121 		return -1;
    122 	}
    123 	if (cfsetispeed(&tty, (speed_t)baud) < 0) {
    124 		snprintf(err, ERRLEN, "cfsetispeed: %s", strerror(errno));
    125 		return -1;
    126 	}
    127 	tty.c_cflag = (tty.c_cflag&~CSIZE) | CS8;
    128 	tty.c_iflag = IGNBRK;
    129 	tty.c_lflag = 0;
    130 	tty.c_oflag = 0;
    131 	tty.c_cflag |= CLOCAL|CREAD;
    132 	tty.c_cc[VMIN] = 1;
    133 	tty.c_cc[VTIME] = 5;
    134 	tty.c_iflag &= ~(IXON|IXOFF|IXANY); // TODO: xon, xoff?
    135 	// TODO: parity
    136 	tty.c_cflag &= ~CSTOPB; // stop bit == 1
    137 	if (tcsetattr(fd, TCSANOW, &tty) < 0) {
    138 		snprintf(err, ERRLEN, "tcseattr: %s", strerror(errno));
    139 		return -1;
    140 	}
    141 	// TODO: rs485
    142 	return 0;
    143 }
    144 
    145 int
    146 flush(int fd)
    147 {
    148 	int out = 0;
    149 	return ioctl(fd, TIOCFLUSH, &out);
    150 }