C Exmaple
You can write the Serial port as the follow demo, the linux inode for the CORE9G25 board is as follow:
Serial Port |
Linux Inode |
Debug serial |
/dev/ttyS0 |
USART0 |
/dev/ttyS1 |
USART1 |
/dev/ttyS2 |
USART2 |
/dev/ttyS3 |
USART3 |
/dev/ttyS4 |
UART0 |
/dev/ttyS5 |
UART1 |
/dev/ttyS6 |
For the Serial port pin define details, you can see the Pin out page
For the C demo, please see the follow word, you can find it at hte CD://linux/example/serial/comtest.c,
#include "stdio.h"
#include "string.h"
#include "unistd.h"
#include "fcntl.h"
#include "errno.h"
#include "sys/types.h"
#include "sys/stat.h"
#include "stdlib.h"
#include "stdarg.h"
#include "termios.h"
int main(void) {
char txBuffer[10];
char rxBuffer[10];
int fd;
struct termios tty_attributes;
if ((fd = open("/dev/ttyS1",O_RDWR|O_NOCTTY|O_NONBLOCK))<0) {
fprintf (stderr,"Open error on %s\n", strerror(errno));
exit(EXIT_FAILURE);
} else {
tcgetattr(fd,&tty_attributes);
// c_cflag
// Enable receiver
tty_attributes.c_cflag |= CREAD;
// 8 data bit
tty_attributes.c_cflag |= CS8;
// c_iflag
// Ignore framing errors and parity errors.
tty_attributes.c_iflag |= IGNPAR;
// c_lflag
// DISABLE canonical mode.
// Disables the special characters EOF, EOL, EOL2,
// ERASE, KILL, LNEXT, REPRINT, STATUS, and WERASE, and buffers by lines.
// DISABLE this: Echo input characters.
tty_attributes.c_lflag &= ~(ICANON);
tty_attributes.c_lflag &= ~(ECHO);
// DISABLE this: If ICANON is also set, the ERASE character erases the preceding input
// character, and WERASE erases the preceding word.
tty_attributes.c_lflag &= ~(ECHOE);
// DISABLE this: When any of the characters INTR, QUIT, SUSP, or DSUSP are received, generate the corresponding signal.
tty_attributes.c_lflag &= ~(ISIG);
// Minimum number of characters for non-canonical read.
tty_attributes.c_cc[VMIN]=1;
// Timeout in deciseconds for non-canonical read.
tty_attributes.c_cc[VTIME]=0;
// Set the baud rate
cfsetospeed(&tty_attributes,B115200);
cfsetispeed(&tty_attributes,B115200);
tcsetattr(fd, TCSANOW, &tty_attributes);
txBuffer[0]='A';
write(fd,txBuffer,1);
// Read a char
if (read(fd,&rxBuffer,1)==1) {
printf("%c",rxBuffer[0]);
printf("\n");
}
}
close(fd);
return EXIT_SUCCESS;
}