usb转串口的通信demo

正文之前：

　　经过这段时间的狠查资料，很感谢那些愿意分享技术的大佬们，像他们学习;

借鉴链接：https://blog.csdn.net/morixinguan/article/details/80898172

直接源码demo：

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <asm/termios.h>
 
 
 
 
//设置停止位
static void set_stopbit (struct termios *opt, const char *stopbit)
{
    if (0 == strcmp (stopbit, "1")) {
        opt->c_cflag &= ~CSTOPB; /* 1 stop bit */
    }   else if (0 == strcmp (stopbit, "1")) {
        opt->c_cflag &= ~CSTOPB; /* 1.5 stop bit */
    }   else if (0 == strcmp (stopbit, "2")) {
        opt->c_cflag |= CSTOPB;  /* 2 stop bits */
    } else {
        opt->c_cflag &= ~CSTOPB; /* 1 stop bit */
    }
}
 
 
//设置校验位
static void set_parity (struct termios *opt, char parity)
{
    switch (parity) {
    case 'N':                  /* no parity check */
        opt->c_cflag &= ~PARENB;
        break;
    case 'E':                  /* even */
        opt->c_cflag |= PARENB;
        opt->c_cflag &= ~PARODD;
        break;
    case 'O':                  /* odd */
        opt->c_cflag |= PARENB;
        opt->c_cflag |= ~PARODD;
        break;
    default:                   /* no parity check */
        opt->c_cflag &= ~PARENB;
        break;
    }
}
 
 
//设置数据位
static void set_data_bit(struct termios *opt, unsigned int databit)
{
    opt->c_cflag &= ~CSIZE;
    switch (databit) {
    case 8:
        opt->c_cflag |= CS8;
        break;
    case 7:
        opt->c_cflag |= CS7;
        break;
    case 6:
        opt->c_cflag |= CS6;
        break;
    case 5:
        opt->c_cflag |= CS5;
        break;
    default:
        opt->c_cflag |= CS8;
        break;
    }
}
 
 
 
//set 波特率
static void set_baudrate (struct termios *opt, unsigned int baudrate)
{
    cfsetispeed(opt, baudrate);
    cfsetospeed(opt, baudrate);
}
 
 
static int set_serial(int fd,struct termios* opt)
{
    set_baudrate(opt,9200);
    opt->c_cflag          |= CLOCAL | CREAD;
 
    set_data_bit(opt,8);
    set_parity(opt,'N');
    set_stopbit(opt, "1");
 
    //其他设置
    opt->c_oflag          = 0;
        opt->c_lflag             |= ICANON;
        opt->c_oflag             &= ~OPOST;
    opt->c_cc[VTIME] = 0;  // 规范模式
    opt->c_cc[VMIN]  = 0;  // 规范模式
 
    tcflush (fd, TCIOFLUSH);
 
    return (tcsetattr (fd, TCSANOW, opt));
 
}
 
int main (int argc, char *argv[])
{
    int fd;
    int len, i,ret;
    char rbuf[1024]={0};;
    char wbuf[] = "hello!\n";    //此处的"\n"作用是让read每次收到数据就显示
 
    const char* DEV_NAME;
    //linux串口驱动的默认属性值(9600,8n1,无流控)
     
    struct termios termios_opt;
 
    //可读可写
#ifdef WRITE 
     DEV_NAME =  "/dev/ttyACM0";           //A设备
 
#elif READ
     DEV_NAME =  "/dev/ttyGS0";                //B设备
     
#endif
 
    fd = open(DEV_NAME, O_RDWR | O_NOCTTY);
    if(fd < 0) {
        perror(DEV_NAME);
        return -1;
    }
 
    //设置串口信息
    ret = set_serial(fd, &termios_opt);
    printf("set serial:%d\n",ret);
 
 
#ifdef WRITE
    len = write(fd, wbuf, sizeof(wbuf));
    if (len < 0) {
        printf("write data error \n");
    }
    printf("write data success: %d \n",len);
     
 
#elif READ
    while(1){
        tcflush (fd, TCIOFLUSH);                         //清空串口的read缓冲区-底层
        memset(rbuf, 0, sizeof(rbuf));              　　 //置0, ----应用层，避免上次buf数据干扰
        len = read(fd, rbuf, sizeof(rbuf));
        if (len < 0) {
            printf("read error \n");
            return -1;
        }
 
        printf("%d: %s", len, rbuf);
    }
 
#endif
 
    close(fd);
 
    return(0);
}