Open a serial port
#include <sys/modem.h> int modem_open( char* device, speed_t baud );
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
This function is in libc.a, but not in libc.so (in order to save space). |
The modem_open() function opens a serial port identified by device. The device is set to raw mode by changing the control flags using tcgetattr() and tcsetattr() as follows:
termio.c_cflag = CS8|IHFLOW|OHFLOW|CREAD|HUPCL; termio.c_iflag = BRKINT; termio.c_lflag = IEXTEN; termio.c_oflag = 0;
Any pending input or output characters are discarded.
If baud is nonzero, then the baud rate is changed to that value.
An open file descriptor, or -1 on failure (errno is set).
#include <stdlib.h> #include <unistd.h> #include <string.h> #include <fcntl.h> #include <sys/modem.h> #include <stdio.h> #include <errno.h> /* curstate curflags newstate newflags newtimeout newquiet retvalue pattern response */ struct modem_script table[] ={ {1, 0, 1, 0, 2, 5, 0, NULL, "ATZ\\r\\P0a"}, {1, 0, 2, 0, 30, 5, 0, "*ok*", "ATDT5910934"}, {2, MODEM_BAUD, 3, MODEM_LASTLINE, 10, 5, 0, "*connect*", NULL}, {3, 0, 4, 0, 8, 5, 0, "*login:*", "guest"}, {4, MODEM_NOECHO, 5, 0, 15, 5, 0, "*password:*", "xxxx"}, {5, 0, 0, 0, 0, 0, 0, "*$ *", NULL}, {0, 0, 0, 0, 0, 0, 1, "*no carrier*", NULL}, {0, 0, 0, 0, 0, 0, 2, "*no answer*", NULL}, {0, 0, 0, 0, 0, 0, 3, "*no dialtone*", NULL}, {0, 0, 0, 0, 0, 0, 4, "*busy*", NULL}, { NULL } }; void io(char* progress, char* in, char* out) { if(progress) printf("progress: %s\n", progress); if(in) printf("input: %s\n", in); if(out) printf("output: %s\n", out); } int main(int argc, char* argv[]) { int fd, status; speed_t baud = -1; if((fd = modem_open(argv[1], 0)) == -1) { fprintf(stderr, "Unable to open %s: %s\n", argv[1], strerror(errno)); exit(1); } status = modem_script( fd, table, &baud, &io, NULL ); printf("status=%d baud=%d\n", status, baud); exit(status); }
Safety: | |
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Cancellation point | Yes |
Interrupt handler | No |
Signal handler | Yes |
Thread | Yes |
modem_read(), modem_script(), modem_write()