串口读写，select 检测有数据时就接收，防止阻塞问题
Makefile:
EXEC = uart_raw OBJS = uart_raw.o SRC = uart_raw.c #CC = arm-none-linux-gnueabi-gcc CC = /home/hongzhunzhun/work/OpenWrt-SDK-sunxi-for-linux-x86_64-gcc-4.8-linaro_uClibc-0.9.33.2/staging_dir/toolchain-arm_cortex-a7+neon_gcc-4.8-linaro_uClibc-0.9.33.2_eabi/bin/arm-openwrt-linux-uclibcgnueabi-g++ CFLAGS += -O2 -Wall LDFLAGS += all:$(EXEC) $(EXEC):$(OBJS) $(CC) $(LDFLAGS) -o $@ $(OBJS) %.o:%.c $(CC) $(CFLAGS) -c $< -o $@ clean: @rm -vf $(EXEC) *.o *~
uart_raw.c:
1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <unistd.h> 4 #include <sys/types.h> 5 #include <sys/stat.h> 6 #include <fcntl.h> 7 #include <termios.h> 8 #include <errno.h> 9 #include <limits.h> 10 #include <unistd.h> 11 #include <string.h> 12 #include <signal.h> 13 14 #define DEV_NAME "/dev/ttyS2" 15 16 int testi=0; 17 //不调用 18 int recv_protocol(int uart_fd,char* buf, int n) 19 { 20 int rc, i; 21 int count = 0; 22 23 while(read(uart_fd, buf, n) >0) 24 { 25 printf("recv serial----rc is %d testi is %d \n ",rc,testi); 26 for(i = 0; i < n; i++) 27 printf(" %x ", buf[i]); 28 } 29 printf("no while !!!\n"); 30 for(i = 0; i < n; i++) 31 printf(" %x ", buf[i]); 32 33 printf("\n"); 34 35 tcflush(uart_fd, TCIOFLUSH); 36 return rc; 37 } 38 39 // 等待时间 串口描述符 读取的buff 40 int Select_Tart_Read(struct timeval tv,int uart_fd,char* buff) 41 { 42 43 memset(buff,0,sizeof(char)*8); 44 fd_set rfds; 45 int retval=0; 46 int i; 47 48 FD_ZERO(&rfds); 49 FD_SET(uart_fd, &rfds); 50 51 retval=select(uart_fd + 1, &rfds, NULL, NULL, &tv); 52 if(retval<0) 53 { 54 perror("select error\n"); 55 } 56 else 57 { 58 if( retval && FD_ISSET(uart_fd, &rfds) ) 59 { 60 testi++; 61 printf("FD_ISSET!\n"); 62 int rc=read(uart_fd, buff, 8); 63 if(rc>0) 64 { 65 printf("recv serial----rc is %d testi is %d \n ",rc,testi); 66 for(i = 0; i < 8; i++) 67 printf(" %x ", buff[i]); 68 printf("\n"); 69 return rc; 70 } 71 } 72 } 73 return 0; 74 } 75 76 77 int monitor_routine( int uart_fd) 78 { 79 int i; 80 printf("in monitor_routine\n"); 81 82 char rebuff[8];//设置最大的数据长度为8个 83 memset(rebuff,0,sizeof(char)*8); 84 struct timeval tv; 85 tv.tv_sec = 0; 86 tv.tv_usec = 10000; 87 int retval; 88 unsigned char commbuff[8];//设置最大的数据长度为8个 89 memset(commbuff,0,sizeof(unsigned char)*8); 90 91 while(1) 92 { 93 //printf("retval is %d\n",retval); 94 if(Select_Tart_Read(tv,uart_fd,rebuff)>0)// 95 { 96 printf("in while Read!\n"); 97 for(i = 0; i < 8; i++) 98 printf(" %x ", rebuff[i]); 99 printf("\n"); 100 } 101 } 102 return 0; 103 } 104 105 106 int main(int argc, char *argv[]) 107 { 108 int iFd, i; 109 int len; 110 unsigned char ucBuf[100]; 111 struct termios opt; 112 113 iFd = open(DEV_NAME, O_RDWR | O_NOCTTY); 114 115 if(iFd < 0) { 116 perror(DEV_NAME); 117 printf(" open /dev/ttyS2 faurel!\n"); 118 return -1; 119 } 120 else 121 printf(" open /dev/ttyS2 !\n"); 122 tcgetattr(iFd, &opt); 123 cfsetispeed(&opt, B115200); 124 cfsetospeed(&opt, B115200); 125 126 if (tcgetattr(iFd, &opt)<0) { 127 return -1; 128 } 129 opt.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG); 130 opt.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON); 131 opt.c_oflag &= ~(OPOST); 132 opt.c_cflag &= ~(CSIZE | PARENB); 133 opt.c_cflag |= CS8; 134 135 opt.c_cc[VMIN] = 255; 136 opt.c_cc[VTIME] = 150; 137 138 if (tcsetattr(iFd, TCSANOW, &opt)<0) { 139 return -1; 140 } 141 tcflush(iFd,TCIOFLUSH); 142 143 144 for (i = 0; i < 100; i++){ 145 ucBuf[i] = 0xff - i; 146 } 147 148 149 char buff[6]; 150 buff[0]=0x05;buff[1]=0x05;buff[2]=0x05;buff[3]=0x05;buff[4]=0x05;buff[5]=0x05; 151 152 153 printf("buff is :\n"); 154 for(i=0;i<6;i++) 155 printf("0x%x ",buff[i]); 156 printf("\n"); 157 158 printf("write buff!!!"); 159 160 len = write(iFd, buff, 6); 161 162 if(len < 0) { 163 164 printf(" write error ! \n"); 165 return -1; 166 } 167 168 printf("in main monitor_routine\n"); 169 170 monitor_routine(iFd); 171 172 printf("\n"); 173 174 175 176 close(iFd); 177 return 0; 178 }
测试：
