linux 串口
while(1){printf("\n--1--\n");
if((nread = read(fd,buff,512))>0)
{ printf("start to read the device %s \n", dev);
printf("\nLen %d\n",nread);
buff='\0';
printf("\n%s",buff);
}
printf("\n--2--"\n);
}
Linux下,能打印出--1--,但是不能执行到--2--
死在if((nread = read(fd,buff,512))>0)上,求解!设备一直往串口上发送0x55.1s一次
#include <stdio.h> /*标准输入输出定义*/
#include <stdlib.h> /*标准函数库定义*/
#include <unistd.h> /*Unix标准函数定义*/
#include <sys/types.h>/**/
#include <sys/stat.h> /**/
#include <fcntl.h> /*文件控制定义*/
#include <termios.h> /*PPSIX终端控制定义*/
#include <errno.h> /*错误号定义*/
/***@brief设置串口通信速率
*@paramfd 类型 int打开串口的文件句柄
*@paramspeed类型 int串口速度
*@returnvoid*/
#define FALSE 1
#define TRUE 0
char *recchr="We received:\"";
int speed_arr[] = { B921600, B460800, B230400, B115200, B57600, B38400, B19200, B9600, B4800, B2400, B1200, B300, B38400, B19200, B9600, B4800, B2400, B1200, B300, };
int name_arr[] = {921600, 460800, 230400, 115200, 57600, 38400,19200,9600,4800,2400,1200,300, 38400,19200,9600, 4800, 2400, 1200,300, };
void set_speed(int fd, int speed)
{
int i;
int status;
struct termios Opt;
tcgetattr(fd, &Opt);
for ( i= 0;i < sizeof(speed_arr) / sizeof(int);i++)
{
if(speed == name_arr)
{
tcflush(fd, TCIOFLUSH);
cfsetispeed(&Opt, speed_arr);
cfsetospeed(&Opt, speed_arr);
status = tcsetattr(fd, TCSANOW, &Opt);
if(status != 0)
perror("tcsetattr fd1");
return;
}
tcflush(fd,TCIOFLUSH);
}
}
/**
*@brief 设置串口数据位，停止位和效验位
*@paramfd 类型int打开的串口文件句柄*
*@paramdatabits 类型int 数据位 取值 为 7 或者8*
*@paramstopbits 类型int 停止位 取值为 1 或者2*
*@paramparity类型int效验类型 取值为N,E,O,,S
*/
int set_Parity(int fd,int databits,int stopbits,int parity)
{
struct termios options;
if( tcgetattr( fd,&options)!=0)
{
perror("SetupSerial 1");
return(FALSE);
}
options.c_cflag &= ~CSIZE;
switch (databits) /*设置数据位数*/
{
case 7:
options.c_cflag |= CS7;
break;
case 8:
options.c_cflag |= CS8;
break;
default:
fprintf(stderr,"Unsupported data size\n");
return (FALSE);
}
switch (parity)
{
case 'n':
case 'N':
options.c_cflag &= ~PARENB; /* Clear parity enable */
options.c_iflag &= ~INPCK; /* Enable parity checking */
break;
case 'o':
case 'O':
options.c_cflag |= (PARODD | PARENB);/* 设置为奇效验*/
options.c_iflag |= INPCK; /* Disnable parity checking */
break;
case 'e':
case 'E':
options.c_cflag |= PARENB; /* Enable parity */
options.c_cflag &= ~PARODD; /* 转换为偶效验*/
options.c_iflag |= INPCK; /* Disnable parity checking */
break;
case 'S':
case 's':/*as no parity*/
options.c_cflag &= ~PARENB;
options.c_cflag &= ~CSTOPB;
break;
default:
fprintf(stderr,"Unsupported parity\n");
return (FALSE);
}
/* 设置停止位*/
switch (stopbits)
{
case 1:
options.c_cflag &= ~CSTOPB;
break;
case 2:
options.c_cflag |= CSTOPB;
break;
default:
fprintf(stderr,"Unsupported stop bits\n");
return (FALSE);
}
if (parity != 'n')
options.c_iflag |= INPCK;
options.c_cc = 150; // 15 seconds
options.c_cc = 0;
tcflush(fd,TCIFLUSH); /* Update the options and do it NOW */
if (tcsetattr(fd,TCSANOW,&options) != 0)
{
perror("SetupSerial 3");
return (FALSE);
}
return (TRUE);
}
/**
*@breif 打开串口
*/
int OpenDev(char *Dev)
{
int fd = open( Dev, O_RDWR); //| O_NOCTTY | O_NDELAY
if (-1 == fd)
{ /*设置数据位数*/
perror("Can't Open Serial Port");
return -1;
}
else
return fd;
}
/**
*@breifmain()
*/
int main(int argc, char *argv[])
{
int fd;
int nread;
char buff;
char *dev ="/dev/ttyUSB0";
int device, c;
printf("Select a port to test (0-6) \n");
AGAIN:
if(scanf("%d", &device)!=EOF){
while((c=getchar())!='\n' && c!=EOF){
;
}
}
if(device==0){
printf("ttyUSB0 is selected \n");
dev="/dev/ttyUSB0";
}
else if(device==1){
printf("ttyUSB1 is selected \n");
dev="/dev/ttyUSB1";
}
else if(device==2){
printf("ttyUSB2 is selected \n");
dev="/dev/ttyUSB2";
}
else if(device==3){
printf("ttyUSB3 is selected \n");
dev="/dev/ttyUSB3";
}
else if(device==4){
printf("ttyUSB4 is selected \n");
dev="/dev/tttyUSB4";
}
else if(device==5){
printf("ttyUSB5 is selected \n");
dev="/dev/ttyUSB5";
}
else if(device==6){
printf("ttyUSB6 is selected \n");
dev="/dev/ttyUSB6";
}
else{
printf("Invalid choice, please try again! \n");
goto AGAIN;
}
sleep(1);
fd = OpenDev(dev);
if (fd>0){
set_speed(fd,115200);
}
else{
printf("Can't Open Serial Port!\n");
exit(0);
}
if (set_Parity(fd,8,1,'N')== FALSE)
{
printf("Set Parity Error\n");
exit(1);
}
printf("start to read the device %s \n", dev);
while(1)
{ printf("start to read the device %s \n", dev);
if((nread = read(fd,buff,512))>0)
{ printf("start to read the device %s \n", dev);
printf("\nLen %d\n",nread);
buff='\0';
printf("\n%s",buff);
//write(fd, recchr, 13);
//write(fd, buff, nread-1);
//write(fd, "\"\n", 2);
}
/*
if(device==0)write(fd,"01234567\n",9);
if(device==1)write(fd,"12345678\n",9);
if(device==2)write(fd,"23456789\n",9);
if(device==3)write(fd,"3456789a\n",9);
if(device==4)write(fd,"456789ab\n",9);
if(device==5)write(fd,"56789abc\n",9);
if(device==6)write(fd,"6789abcd\n",9);
sleep(1);*/
}
close(fd);
exit(0);
} sudo chmod a+rw /dev/ttyUSB0 帮你顶。
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