linux 串口测试指令和测试程序

一、串口设备查看

查看串口 (/dev)

ls /dev/tty*

查看串口（或串口终端）属性 ( /proc)

cat /proc/tty/driver/serial                                                                                                              或
cat /proc/tty/drivers

二、串口自测指令

测试打印口

echo haha > /dev/ttyS0

测试串口4
使用usb转ttl连接串口4，配置串口4波特率为9600，打开上位机串口软件循环发送数据。开发板使用指令

cat /dev/ttyS4

开启输出显示，可在调试串口看到串口4接收到上位机发送的数据.

三、串口测试参考程序

连接方式：以nuc980开发板为例，将串口1和串口2的收、发线交叉连接。
nuc980官方uart测试程序

/****************************************************************************
 *                                                                          *
 * Copyright (c) 2014 Nuvoton Technology Corp. All rights reserved.         *
 *                                                                          *
 ****************************************************************************/
 
/****************************************************************************
 * 
 * FILENAME
 *     uart_test.c
 *
 * VERSION
 *     1.0
 *
 * DESCRIPTION
 *     This is the test program used to test the UARTs on NUC980 EV board
 *
 * DATA STRUCTURES
 *     None
 *
 * FUNCTIONS
 *     None
 *
 * HISTORY
 *     
 *
 * REMARK
 *     None
 ****************************************************************************/
#include     <stdio.h>
#include     <stdlib.h>
#include     <unistd.h> 
#include     <sys/types.h> 
#include     <sys/stat.h> 
#include     <fcntl.h> 
#include     <termios.h>  
#include     <errno.h>
#include     <string.h>
#include     <signal.h>
#include    <pthread.h>

#define FALSE 0
#define TRUE  1

int fd[2];

pthread_t threads[10];

char buff[101];

static struct termios newtios,oldtios; /*termianal settings */
static int saved_portfd=-1;            /*serial port fd */

static void reset_tty_atexit(void)
{
    if(saved_portfd != -1)
    {
        tcsetattr(saved_portfd,TCSANOW,&oldtios);
    } 
}

/*cheanup signal handler */
static void reset_tty_handler(int signal)
{
    if(saved_portfd != -1)
    {
        tcsetattr(saved_portfd,TCSANOW,&oldtios);
    }
    _exit(EXIT_FAILURE);
}

static int open_port(const char *portname)
{
    struct sigaction sa;
    int portfd;

    printf("opening serial port:%s\n",portname);
    /*open serial port */
    if((portfd=open(portname,O_RDWR | O_NOCTTY)) < 0 )
    {
           printf("open serial port %s fail \n ",portname);
           return portfd;
    }

    /*get serial port parnms,save away */
    tcgetattr(portfd,&newtios);
    memcpy(&oldtios,&newtios,sizeof newtios);
    /* configure new values */
    cfmakeraw(&newtios); /*see man page */
    newtios.c_iflag |=IGNPAR; /*ignore parity on input */
    newtios.c_oflag &= ~(OPOST | ONLCR | OLCUC | OCRNL | ONOCR | ONLRET | OFILL); 
    newtios.c_cflag = CS8 | CLOCAL | CREAD;
    newtios.c_cc[VMIN]=1; /* block until 1 char received */
    newtios.c_cc[VTIME]=0; /*no inter-character timer */
    /* 115200 bps */
    cfsetospeed(&newtios,B115200);
    cfsetispeed(&newtios,B115200);
    /* register cleanup stuff */
    atexit(reset_tty_atexit);
    memset(&sa,0,sizeof sa);
    sa.sa_handler = reset_tty_handler;
    sigaction(SIGHUP,&sa,NULL);
    sigaction(SIGINT,&sa,NULL);
    sigaction(SIGPIPE,&sa,NULL);
    sigaction(SIGTERM,&sa,NULL);
    /*apply modified termios */
    saved_portfd=portfd;
    tcflush(portfd,TCIFLUSH);
    tcsetattr(portfd,TCSADRAIN,&newtios);
    return portfd;
}

void * process1(void* arg)
{
    int portfd = (int) arg;
    unsigned char i, j;
    int rev1, rev2;
    char RxBuffer[101];    

    rev1 =0;
    rev2 =0;

    while(rev2 < 100)
       {
        rev1 = write(portfd,(buff+rev2),100);
        rev2 += rev1;
       }

    printf("\n uart1 send %d byts\n", rev2);

    rev1 = 0;
    rev2 = 0;

    while(rev2 < 100)
    {
        rev1 = read(portfd,(RxBuffer+rev2),100);
        rev2 += rev1;
    }
        
    printf("\n uart1 receive %d bytes\n", rev2);

    for(i = 0; i < 100; i++)
    {
        if(i != RxBuffer[i])
        {
            printf("\n uart1 compare Error!!");
                        
            while(1);
        }
    }

    printf("\n uart1 compare correct!!\n");
    printf("\n uart1 test done!!\n");

}    

void * process2(void* arg)
{
    int portfd = (int) arg;
    unsigned char i, j;
    int rev1, rev2;
    char RxBuffer[101];

    rev1 =0;
    rev2 =0;

    while(rev2 < 100)
       {
        rev1 = write(portfd,(buff+rev2),100);
        rev2 += rev1;
       }

    printf("\n uart2 send %d bytes \n", rev2);

    rev1 = 0;
    rev2 = 0;

    while(rev2 < 100)
    {
        rev1 = read(portfd,(RxBuffer+rev2),100);
        rev2 += rev1;
    }
        
    printf("\n uart2 receive %d bytes \n", rev2);

    for(i = 0; i < 100; i++)
    {
        if(i != RxBuffer[i])
        {
            printf("\n uart2 compare Error!!");
            while(1);
        }
    }

    printf("\n uart2 compare correct!!\n");
    printf("\n uart2 test done!!\n");

}

/**
*@breif     main()
*/
int main(int argc, char **argv)
{
    char *dev[10]={"/dev/ttyS1", "/dev/ttyS2"};
    unsigned int i;

    printf("\n demo uart1/uart2 external loop back function \n");

    for(i = 0; i < 100; i++)
    {
        buff[i] = (i & 0xff);
    }

    for(i = 0; i < 2; i++)
    {
        if((fd[i] = open_port(dev[i]))<0)
               return -1;
    }
    
    pthread_create(&threads[0], NULL, process1, (void*)(fd[0]));
    pthread_create(&threads[1], NULL, process2, (void*)(fd[1]));

    pthread_join(threads[0], NULL);
    pthread_join(threads[1], NULL);

           
  return 0;
}

Makefile文件

.SUFFIXES : .x .o .c .s

CC := arm-linux-gcc
STRIP := arm-linux-strip

TARGET = uart_demo
SRCS := uart.c
LIBS = -lpthread -lc -lgcc

all:
    $(CC) -static $(SRCS) -o $(TARGET) $(LIBS)
    $(STRIP) $(TARGET)

clean:
    rm -f *.o
    rm -f *.x
    rm -f *.flat
    rm -f *.map
    rm -f temp
    rm -f *.img
    rm -f $(TARGET)
    rm -f *.gdb

测试结果

nuc980官方rs485测试程序

/*
 * Copyright (c) 2014 Nuvoton technology corporation
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 */
 
#include     <stdio.h>
#include     <stdlib.h>
#include     <unistd.h> 
#include     <sys/types.h>
#include     <sys/stat.h> 
#include     <fcntl.h> 
#include     <termios.h>  
#include     <errno.h>
#include     <string.h>
#include     <signal.h>
#include    <pthread.h>
#include <linux/serial.h>

#define FALSE 0
#define TRUE  1

/* Driver-specific ioctls: ...\linux-3.10.x\include\uapi\asm-generic\ioctls.h */
#define TIOCGRS485      0x542E
#define TIOCSRS485      0x542F

int fd[2];

pthread_t threads[10];

char buff[256];

static struct termios newtios,oldtios; /*termianal settings */
static int saved_portfd=-1;            /*serial port fd */

/* Test GCC version, this structure is consistent in GCC 4.8, thus no need to overwrite */
#if (__GNUC__ == 4 && __GNUC_MINOR__ == 3)

struct my_serial_rs485
{
    unsigned long    flags;            /* RS485 feature flags */
    #define SER_RS485_ENABLED        (1 << 0)    /* If enabled */
    #define SER_RS485_RTS_ON_SEND        (1 << 1)    /* Logical level for RTS pin when sending */
    #define SER_RS485_RTS_AFTER_SEND    (1 << 2)    /* Logical level for  RTS pin after sent*/
    #define SER_RS485_RX_DURING_TX        (1 << 4)
    unsigned long    delay_rts_before_send;    /* Delay before send (milliseconds) */
    unsigned long    delay_rts_after_send;    /* Delay after send (milliseconds) */
    unsigned long    padding[5];        /* Memory is cheap, new structs  are a royal PITA .. */
};

#endif

static void reset_tty_atexit(void)
{
    if(saved_portfd != -1)
    {
        tcsetattr(saved_portfd,TCSANOW,&oldtios);
    } 
}

/*cheanup signal handler */
static void reset_tty_handler(int signal)
{
    if(saved_portfd != -1)
    {
        tcsetattr(saved_portfd,TCSANOW,&oldtios);
    }
    _exit(EXIT_FAILURE);
}

static int open_port(const char *portname)
{
    struct sigaction sa;
    int portfd;
#if (__GNUC__ == 4 && __GNUC_MINOR__ == 3)
    struct my_serial_rs485 rs485conf;
    struct my_serial_rs485 rs485conf_bak;
#else
    struct serial_rs485 rs485conf;
    struct serial_rs485 rs485conf_bak;
#endif    
    //printf("opening serial port:%s\n",portname);
    /*open serial port */
    if((portfd=open(portname,O_RDWR | O_NOCTTY, 0)) < 0 )
    {
           printf("open serial port %s fail \n ",portname);
           return portfd;
    }

    printf("opening serial port:%s\n",portname);

    /*get serial port parnms,save away */
    tcgetattr(portfd,&newtios);
    memcpy(&oldtios,&newtios,sizeof newtios);
    /* configure new values */
    cfmakeraw(&newtios); /*see man page */
    newtios.c_iflag |=IGNPAR; /*ignore parity on input */
    newtios.c_oflag &= ~(OPOST | ONLCR | OLCUC | OCRNL | ONOCR | ONLRET | OFILL); 
    newtios.c_cflag = CS8 | CLOCAL | CREAD;
    newtios.c_cc[VMIN]=1; /* block until 1 char received */
    newtios.c_cc[VTIME]=0; /*no inter-character timer */
    /* 115200 bps */
    cfsetospeed(&newtios,B9600);
    cfsetispeed(&newtios,B9600);
    /* register cleanup stuff */
    atexit(reset_tty_atexit);
    memset(&sa,0,sizeof sa);
    sa.sa_handler = reset_tty_handler;
    sigaction(SIGHUP,&sa,NULL);
    sigaction(SIGINT,&sa,NULL);
    sigaction(SIGPIPE,&sa,NULL);
    sigaction(SIGTERM,&sa,NULL);
    /*apply modified termios */
    saved_portfd=portfd;
    tcflush(portfd,TCIFLUSH);
    tcsetattr(portfd,TCSADRAIN,&newtios);
    
        
    if (ioctl (portfd, TIOCGRS485, &rs485conf) < 0) 
    {
        /* Error handling.*/ 
        printf("ioctl TIOCGRS485 error.\n");
    }
    /* Enable RS485 mode: */
    rs485conf.flags |= SER_RS485_ENABLED;

    /* Set logical level for RTS pin equal to 1 when sending: */
    rs485conf.flags |= SER_RS485_RTS_ON_SEND;
    //rs485conf.flags |= SER_RS485_RTS_AFTER_SEND;

    /* set logical level for RTS pin equal to 0 after sending: */ 
    rs485conf.flags &= ~(SER_RS485_RTS_AFTER_SEND);
    //rs485conf.flags &= ~(SER_RS485_RTS_ON_SEND);

    /* Set rts delay after send, if needed: */
    rs485conf.delay_rts_after_send = 0x80;

    if (ioctl (portfd, TIOCSRS485, &rs485conf) < 0)
    {
        /* Error handling.*/ 
        printf("ioctl TIOCSRS485 error.\n");
    }

    if (ioctl (portfd, TIOCGRS485, &rs485conf_bak) < 0)
    {
        /* Error handling.*/ 
        printf("ioctl TIOCGRS485 error.\n");
    }
    else
    {
        printf("rs485conf_bak.flags 0x%x.\n", rs485conf_bak.flags);
        printf("rs485conf_bak.delay_rts_before_send 0x%x.\n", rs485conf_bak.delay_rts_before_send);
        printf("rs485conf_bak.delay_rts_after_send 0x%x.\n", rs485conf_bak.delay_rts_after_send);
    }

    return portfd;
}

void * process1(void* arg)
{
    int portfd = (int) arg;
    unsigned int i, j;
    int rev1, rev2;
    char RxBuffer[sizeof(buff)];    

    rev1 =0;
    rev2 =0;

    while(rev2 < sizeof(buff))
       {
        rev1 = write(portfd,(buff+rev2),sizeof(buff));
        rev2 += rev1;
       }
    printf("\n uart1 send %d byts\n", rev2);

}    

void * process2(void* arg)
{
    int portfd = (int) arg;
    unsigned int i, j;
    int rev1, rev2;
    char RxBuffer[sizeof(buff)];

    rev1 = 0;
    rev2 = 0;

    while(rev2 < sizeof(RxBuffer))
    {
        rev1 = read(portfd,(RxBuffer+rev2),sizeof(RxBuffer) - rev2);
        rev2 += rev1;

        if(rev1 > 0)
            printf("\n uart2 receive %d bytes \n", rev2);
    }
        
    printf("\n uart2 receive %d bytes \n", rev2);

    for(i = 0; i < sizeof(RxBuffer); i++)
    {
        if(i != RxBuffer[i])
        {
            printf("\n uart2 compare Error!!");
            while(1);
        }
    }

    printf("\n uart2 compare correct!!\n");
    printf("\n uart2 test done!!\n");

}

/**
*@breif     main()
*/
int main(int argc, char **argv)
{
    char *dev[10]={"/dev/ttyS1", "/dev/ttyS2"};
    unsigned int i;

    printf("\n demo uart1/uart2 external loop back function \n");

    for(i = 0; i < sizeof(buff); i++)
    {
        buff[i] = (i & 0xff);
    }

    for(i = 0; i < 2; i++)
    {
        if((fd[i] = open_port(dev[i]))<0)
               return -1;
    }
    
    pthread_create(&threads[0], NULL, process1, (void*)(fd[0]));
    pthread_create(&threads[1], NULL, process2, (void*)(fd[1]));

    pthread_join(threads[0], NULL);
    pthread_join(threads[1], NULL);

           
  return 0;
}

Makefile文件

.SUFFIXES : .x .o .c .s

CC := arm-linux-gcc
STRIP := arm-linux-strip

TARGET = uart_rs485
SRCS := uart.c
LIBS = -lpthread -lc -lgcc

all:
    $(CC) -static $(SRCS) -o $(TARGET) $(LIBS)
    $(STRIP) $(TARGET)

clean:
    rm -f *.o
    rm -f *.x
    rm -f *.flat
    rm -f *.map
    rm -f temp
    rm -f *.img
    rm -f $(TARGET)
    rm -f *.gdb