linux环境下C语言实现非阻塞方式读取字符串数据的串口测试程序,即串口工具的编写

1、linux环境下C语言实现非阻塞方式读取字符串数据的串口测试程序，即串口工具的编写一、前言1.1 关于串口测试工具，网上已经有集成好的应用程序提供大家使用，但其只提供功能接口，内部具体怎么实现的还需要自己去探索； 1.2 关于串口通信的测试程序在网上已经是数见不鲜，但也不排除很多是直接“参考”别人的（ctrl+c），而且很多代码没有相关注释，从而某些细节性的问题就被忽略； 1.3 本例程序不需全部读完，分为3大部分，设置通信协议、读写字符串函数编写、通信的测试函数，测试函数自己选取看两个典型的就OK；如果哪有说的有误，希望大家指正，多交流共同进步； 1.4 要点：本文提供了设置串口通讯的接口，

2、方便大家对程序的复用，感觉还是面向对象的语言更方便呀；在给模块发送指令后需要读取模块返回的数据时，保险起见采用阻塞式读取，且串口一次只能读取8位byte数据，注意读取数据的调用函数；注意在读写命令中存在0x00(零)的16进制的数据时的方式；通信成功，但恰遇到模块总返回操作失败的代码的问题。二、串口测试程序的实现2.1 要实现串口通信的操作，首先是找到需要操作的对象，即具体的串口设备，一般都在Linux嵌入式设备的/dev/路径下有很多串口设备，找到自己所要操作的串口设备，例如本例程所操作的是/dev/ttySAC0, ttySAC0为串口设备名称；2.2 模块的串口通信协议，不同的模块之间有

3、细微差别，自己作相应的改动就好。本例程的通信协议：波特率9600bps, 8位数据位，1位起始位，一位停止位,无奇偶校验。通信成功时，返回的是操作成功或者操作失败的代码，PS：操作失败并不是说的是通信失败，因为去访问模块时，模块给了应答，表明通信是成功的，只能说明是硬件本身操作失败。发送的指令中存在CS，其值为0减去前面CS前面所有16进制的相加-例：80 06 05 01 CS, CS为：0-（80+06+05+01）=74 ，即需要发送的代码为80 06 05 01 74；2.3 源码如下：#include#include#include#include#include#include#i

4、nclude#include#include#define TRUE 1#define FALSE -1#define BUFF_MAXSIZE 2048#define FREQUENCY_00 0 /设定的频率为0#define FREQUENCY_05 5 /设定的频率为5#define FREQUENCY_10 10 /设定的频率为10#define FREQUENCY_20 20 /设定的频率为20#define RESOLUTION_ONE_MM 1 /1表示选择设定的分辨率为1mm#define RESOLUTION_Z_P_ONE_MM 2 /2表示选择设定的分辨率为0.1mm#

5、define MEASURING_POWER_ON 1 /1表示上电即测开启 #define MEASURING_POWER_OFF 0 /0表示上电即测关闭typedef unsigned char un_char;/初始化设置，即设置通信协议int OpenDev(char *dev);/打开串口设备文件int set_speed(int fd, int speed, struct termios* newtio);/设置波特率int Set_Parity(int fd, int databits, int stopbits, int parity);/设置数据位、停止位、校验位/数据读写

6、函数int Write_Data(int fd, void *buf, int len);/发送命令代码函数int Read_Data(int fd, char *buff);/接收命令代码函数/模块的功能函数int Open_LaserModule(int fd);/模块的打开int Close_LaserModule(int fd);/模块的关闭int Set_Address(int fd);/设置地址un_char* Read_Parameter(int fd, un_char* device_parameter);/读取参数un_char* Read_Device_Num(int fd

7、, un_char* device_num);/读取机器号int Distance_Modification(int fd, int decrease_or_increase, int distance_int);/距离修改,参数decrease_or_increase表示修正可选为取负或者取正，参数distance表示要修正的距离int Mea_Interval(int fd, int interval_time_int);/连续测量时设置数据返回时间间隔,参数interval_time_int表示要设定的时间间隔为interval_time_int秒int Distance_StartSt

8、op(int fd, int position_int);/设置距离起止点,参数position_int的值(1顶端算起；0加上模块长度+上面的距离修正)int Set_MeasuringRange(int fd, int range);/设定量程,range表示要设定的量程大小05, 10, 30, 50, 80int Set_Frequency(int fd, int freg);/设定频率,freg表示要设定的频率大小,00,05,10,20int Set_Resolution(int fd, int mode);/设定分辨率,当mode=1表示设定的分辨率为1mm,当mode=2表示设

9、定的分辨率为0.1mmint Measuring_Power(int fd, int on_off);/设定上电即测,on_off=1表示开启该功能，on_off=0表示关闭该功能int Single_Measurement_Broadcast(int fd);/单次测量（广播命令，返回结果存入模块缓存）un_char* Read_Cache(int fd, un_char* cache_data);/读取缓存un_char* Single_Measurement(int fd, un_char* single_mea);/单次测量un_char* Continuous_Measurement

10、(int fd, un_char* continuous_mea);/连续测量int speed_arr=B115200, B38400, B19200, B9600, B4800, B2400, B1200, B300, B38400, B19200, B9600, B4800, B2400, B1200, B300;int name_arr=115200, 38400, 19200, 9600, 4800, 2400, 1200, 300, 115200, 38400, 19200, 9600, 4800, 2400, 1200, 300;int main(int argc, char *

11、argv) int fd; un_char Buff_data_deviceBUFF_MAXSIZE = 0;/我只是测试用，就在栈分配的空间，正式编写一般需要自己分配动态内存 struct termios oldtio, newtio; /打开串口 char *dev = /dev/ttySAC0; fd = OpenDev(dev); tcgetattr(fd, &oldtio); if(fd 0) set_speed(fd, 9600, &newtio);/设置9600bps波特率 else printf(Cant Open Serial Port!/n); exit(0); if(Se

12、t_Parity(fd, 8, 1, S) = FALSE)/调用设置8位数据位，1位停止位及无校验位 printf(Set Parityu Error!/n); exit(1); /测试函数的调用 Open_LaserModule(fd); Set_Resolution(fd, RESOLUTION_Z_P_ONE_MM); Measuring_Power(fd, MEASURING_POWER_ON); Set_Frequency(fd, FREQUENCY_05); Set_MeasuringRange(fd, RANGE_80); sleep(5); Read_Parameter(fd

13、, Buff_data_device); Set_Address(fd); Distance_Modification(fd, DISTANCE_IN, 2); Mea_Interval(fd, 5); Distance_StartStop(fd, 0); sleep(5); Read_Cache(fd, Buff_data_device); sleep(5); Single_Measurement(fd, Buff_data_device); sleep(5); Continuous_Measurement(fd, Buff_data_device); Close_LaserModule(f

14、d); close(fd);/打开文件设备int OpenDev(char *dev) int fd = open(dev, O_RDWR | O_NOCTTY | O_NDELAY); if(fd = -1) printf(Cant Open Serial Port!n); return FALSE; else return fd;/设置波特率int set_speed(int fd, int speed, struct termios* newtio) int i; int status; struct termios* Opt = newtio; tcgetattr(fd, Opt);

15、for(i = 0; i sizeof(speed_arr)/sizeof(int); i+) if(speed = name_arri) tcflush(fd, TCIOFLUSH); cfsetispeed(Opt, speed_arri); cfsetospeed(Opt, speed_arri); status = tcsetattr(fd, TCSANOW, Opt); if(status != 0) printf(tcsetattr failed!n); return FALSE; tcflush(fd, TCIOFLUSH); return TRUE;/设置fd的数据位、停止位、

16、奇偶检验位int Set_Parity(int fd, int databits, int stopbits, int parity) struct termios options; if(tcgetattr(fd, &options) != 0) printf(Setup Serial 1 error!n); return FALSE; /对options的起始地址开始的termios结构体内存置零 bzero(&options,sizeof(options); options.c_cflag &= CSIZE; /选择数据位 switch(databits) case 7:options.

17、c_cflag |= CS7; break; case 8:options.c_cflag |= CS8; break; default:printf(Unsupported data size!/n); return FALSE; /选择奇偶校验 switch(parity) case n: case N: options.c_cflag &= (PARENB); options.c_cflag &= (INPCK); break; case o:/偶校验 case O: options.c_cflag |= (PARODD | PARENB); options.c_cflag |= INP

18、CK; break; case e:/偶校验 case E: options.c_cflag |= PARENB; options.c_cflag &= (PARODD); options.c_cflag |= INPCK; break; case s:/无奇偶校验 case S: options.c_cflag &= (PARENB); options.c_cflag &= (CSTOPB); break; default: printf(Unsupported parity!/n); return FALSE; /选择停止位 switch(stopbits) case 1: options

19、.c_cflag &= (CSTOPB); break; case 2: options.c_cflag |= CSTOPB; break; default: printf(Unsupported stop bits!/n); return FALSE; if(parity != n) /修改控制模式，保证程序不会占用串口 options.c_cflag |= CLOCAL; /修改控制模式，使得能够从串口中读取输入数据 options.c_cflag |= CREAD; options.c_lflag &= (ICANON | ECHO | ECHOE); options.c_iflag &

20、= (IXON | IXOFF | IXANY); options.c_lflag &= (ICANON | ECHO | ECHOE | ISIG); /*Input*/ options.c_oflag &= OPOST; /有字符处理或经过TIME个0.1秒后返回 options.c_ccVTIME = 0; options.c_ccVMIN = 0; /如果发生数据溢出，接收数据，但是不再读取 tcflush(fd, TCIFLUSH); /激活配置 (将修改后的termios数据设置到串口中） if(tcsetattr(fd, TCSANOW, &options) != 0) prin

21、tf(Setup Serial error!n); return FALSE; return 0;/写数据函数int Write_Data(int fd, void *buf, int len) int m_fd = fd; int write_count = 0; int nwrite = 0; if(m_fd 0) nwrite = write(fd, (char*)buf + write_count, len); if(nwrite 1) printf(Write Datda Fail!n); break; write_count += nwrite; len -= nwrite; /

22、清除所有正在发生的I/O数据 tcflush(fd, TCIOFLUSH); return write_count;/读取数据int Read_Data(int fd, char* buff) int nread = 0; int fd_max; int nselect; fd_set readfds; FD_ZERO(&readfds); FD_SET(fd,&readfds); fd_max = fd+1; nselect = select(fd_max, &readfds, NULL, NULL, NULL); memset(buff, 0, sizeof(buff); if(nsele

23、ct 0) nread = read(fd, buff, 8); buffnread = 0; int j = 0; while(buffj != 0) printf(the readable data is 0x%xn, buffj); j+; return nread;/开启模块 int Open_LaserModule(int fd) un_char Buff_OpenBUFF_MAXSIZE = 0x80, 0x06, 0x05, 0x01, 0x74; un_char Open_SucceededBUFF_MAXSIZE = 0x80, 0x06, 0x85, 0x01, 0xF4;

24、 un_char Open_FailedBUFF_MAXSIZE = 0x80, 0x06, 0x85, 0x00, 0xF5; Write_Data(fd, Buff_Open, strlen(Buff_Open); Read_Data(fd, Buff_Open); if(strcmp(Buff_Open, Open_Succeeded) = 0) printf(Open_LaserModule Succeeded!n); else if(strcmp(Buff_Open, Open_Failed) = 0) printf(Open_LaserModule Failed, Please T

25、ry Again!n); else printf(NGn); return FALSE; return TRUE;/关闭模块 int Close_LaserModule(int fd) un_char Buff_CloseBUFF_MAXSIZE = 0x80, 0x06, 0x05, 0x00, 0x75; un_char Close_SucceededBUFF_MAXSIZE = 0x80, 0x06, 0x85, 0x01, 0xF4; un_char Close_FailedBUFF_MAXSIZE = 0x80, 0x06, 0x85, 0x00, 0xF5; /要写的数据中间有0x

26、00，因此把要的数据长度指定为5个字节，而不用strlen()函数计算长度 Write_Data(fd, Buff_Close, 5); Read_Data(fd, Buff_Close); if(strcmp(Buff_Close, Close_Succeeded) = 0) printf(Close_LaserModule Succeeded!n); else if(strcmp(Buff_Close, Close_Failed) = 0) printf(Close_LaserModule Failed, Please Try Again!n); else printf(NGn); ret

27、urn FALSE; return TRUE;/读取参数un_char* Read_Parameter(int fd, un_char* device_parameter) un_char Buff_Read_ParameterBUFF_MAXSIZE = 0xFA, 0x06, 0x01, 0xFF; Write_Data(fd, Buff_Read_Parameter, strlen(Buff_Read_Parameter); Read_Data(fd, Buff_Read_Parameter); printf(*The parameter have read!*n); strcpy(de

28、vice_parameter, Buff_Read_Parameter); return device_parameter;/读取机器号,由于串口每次只能读取8个字节，而读取机器号的返回代码有20个字节，所以读取三次数据un_char* Read_Device_Num(int fd, un_char* device_num) int nread = 0; un_char Buff_Read_DeviceNumBUFF_MAXSIZE = 0xFA, 0x06, 0x04, 0xFC; un_char Buff_read_backBUFF_MAXSIZE = 0; un_char *Buff_b

29、p = Buff_read_back; Write_Data(fd, Buff_Read_DeviceNum, strlen(Buff_Read_DeviceNum); nread = Read_Data(fd, Buff_Read_DeviceNum); memcpy(Buff_bp, Buff_Read_DeviceNum, nread); Buff_bp += nread; nread = Read_Data(fd, Buff_Read_DeviceNum); memcpy(Buff_bp, Buff_Read_DeviceNum, nread); Buff_bp += nread; n

30、read = Read_Data(fd, Buff_Read_DeviceNum); strcpy(Buff_bp, Buff_Read_DeviceNum); strcpy(device_num, Buff_read_back); return device_num;/设置地址int Set_Address(int fd) un_char Buff_AddressBUFF_MAXSIZE = 0xFA, 0x04, 0x01, 0x80, 0x81; un_char Address_SucceededBUFF_MAXSIZE = 0xFA, 0x04, 0x81, 0x81; un_char

31、 Address_FailedBUFF_MAXSIZE = 0xFA, 0x84, 0x81, 0x02, 0xFF; Write_Data(fd, Buff_Address, strlen(Buff_Address); Read_Data(fd, Buff_Address); if(strcmp(Buff_Address, Address_Succeeded) = 0) printf(Set_Address Succeeded!n); else if(strcmp(Buff_Address, Address_Failed) = 0) printf(Set Address Error, Ple

32、ase Write Again!n); else printf(NGn); return FALSE; return TRUE;/距离修改,参数decrease_or_increase表示修正可选为取负或者取正，参数distance表示要修正的距离int Distance_Modification(int fd, int decrease_or_increase, int distance_int) un_char decrease_increase = (un_char)decrease_or_increase; un_char distance_ch = (un_char)distance

33、_int; int c_s = -250 - 4 - 6 - decrease_or_increase - distance_int;/十进制250表示十六进制0xFA un_char cs = (un_char)c_s; un_char Buff_Distance_MoBUFF_MAXSIZE = 0; Buff_Distance_Mo0 = 0xFA; Buff_Distance_Mo1 = 0x04; Buff_Distance_Mo2 = 0x06; Buff_Distance_Mo3 = decrease_increase; Buff_Distance_Mo4 = distance_

34、ch; Buff_Distance_Mo5 = cs; Buff_Distance_Mo6 = 0; un_char Distance_ModificationSdBUFF_MAXSIZE =0xFA, 0x04, 0x8B, 0x77; un_char Distance_ModificationFdBUFF_MAXSIZE =0xFA, 0x84, 0x8B, 0x01, 0xF6; Write_Data(fd, Buff_Distance_Mo, strlen(Buff_Distance_Mo); Read_Data(fd, Buff_Distance_Mo); if(strcmp(Buf

35、f_Distance_Mo, Distance_ModificationSd) = 0) if(decrease_or_increase = 43) printf(Distance_Increase_Modification_Succeededn); else printf(Distance_Decrease_Modification_Succeededn); else if(strcmp(Buff_Distance_Mo, Distance_ModificationFd) = 0) if(decrease_or_increase = 43) printf(Distance_Increase_

36、Modification_Failedn); else printf(Distance_Decrease_Modification_Failedn); else printf(NGn); return FALSE; return TRUE;/连续测量时设置数据返回时间间隔,参数interval_time_int表示要设定的时间间隔为interval_time_int秒int Mea_Interval(int fd, int interval_time_int) int c_s = -250 - 4 - 5 - interval_time_int;/十进制250表示十六进制0xFA un_cha

37、r cs = (un_char)c_s; un_char interval_ch = (un_char)interval_time_int; un_char Buff_Mea_IntervalBUFF_MAXSIZE = 0; Buff_Mea_Interval0 = 0xFA; Buff_Mea_Interval1 = 0x04; Buff_Mea_Interval2 = 0x05; Buff_Mea_Interval3 = interval_ch; Buff_Mea_Interval4 = cs; Buff_Mea_Interval5 = 0; un_char Mea_IntervalSd

38、BUFF_MAXSIZE = 0xFA, 0x04, 0x85, 0x7D; un_char Mea_IntervalFdBUFF_MAXSIZE = 0xFA, 0x84, 0x85, 0x01, 0xFC; un_char Write_IntervalErrBUFF_MAXSIZE = 0xFA, 0x84, 0x85, 0x01, 0xFA; Write_Data(fd, Buff_Mea_Interval, strlen(Buff_Mea_Interval); Read_Data(fd, Buff_Mea_Interval); if(strcmp(Buff_Mea_Interval,

39、Mea_IntervalSd) = 0) printf(Mea_Interval_Succeededn); else if(strcmp(Buff_Mea_Interval, Mea_IntervalFd) = 0) printf(Mea_Interval_Failed, Please Try Again!n); else if(strcmp(Buff_Mea_Interval, Write_IntervalErr) = 0) printf(Mea_Interval_Errorn); else printf(NGn); return FALSE; return TRUE;/设置距离起止点,参数

40、position_int的值(1顶端算起；0加上模块长度+上面的距离修正)int Distance_StartStop(int fd, int position_int) int c_s = -250 - 4 - 8 - position_int;/十进制250表示十六进制0xFA un_char cs = (un_char)c_s; un_char position_ch = (un_char)position_int; un_char Buff_StartStopBUFF_MAXSIZE = 0; Buff_StartStop0 = 0xFA; Buff_StartStop1 = 0x04

41、; Buff_StartStop2 = 0x08; Buff_StartStop3 = position_ch; Buff_StartStop4 = cs; Buff_StartStop5 = 0; un_char Mea_Distance_StartStopSdBUFF_MAXSIZE = 0xFA, 0x04, 0x88, 0x7A; un_char Mea_Distance_StartStopFdBUFF_MAXSIZE = 0xFA, 0x84, 0x88, 0x01, 0xF9; /要写的数据中间有0x00，因此把要的数据长度指定为5个字节，而不用strlen()函数计算长度 if(Buff_StartStop3 = 0x00) Write_Data(fd, Buff_StartStop, 5); else Write_Data(fd, Buff_StartStop, strlen(Buff_StartStop); Read_Data(fd, Buff_StartStop); if(strcmp(Buff_StartStop, Mea_Distance_StartStopSd) = 0) printf(Mea_Distance_StartStop_Succeeded!n); else if(strcmp(Buff_StartStop,