基本思想：随手记录一下众灵科技树莓派的测试串口通信和超声波模块，其镜像还是很nice，基本的库都给你安装了，比较大
链接：/s/11tMdoRh3bHmcYzPyolm96g
提取码：fd58
第一步、测试树莓派的串口程序
可以通过桌面的设置，在Raspberry Pi Configuration中将Serial Port设置为Enable， 我全部打开了
引脚定义
第二步、根据pin引脚，引入usb转ttl引针，然后打开串口工具
第三步、先使用权限命令打开权限
确定可用的串口
pi@raspberrypi:~/client/build $ ls /dev/ser* -allrwxrwxrwx 1 root root 7 6月 12 09:17 /dev/serial0 -> ttyS0lrwxrwxrwx 1 root root 5 6月 12 09:17 /dev/serial1 -> ttyAMA0pi@raspberrypi:~/client/build $
然后测试
pi@raspberrypi:~/sxj731533730 $ sudo chmod 777 /dev/ttyS0
测试代码
pi@raspberrypi:~/sxj731533730 $ cat a.pyimport serialser = serial.Serial('/dev/ttyS0',9600)ser.isOpen()ser.write('Hello CSDN !!'.encode('utf-8'))
python测试结果
c++测试代码
#include <chrono>#include <sys/stat.h>#include <fcntl.h>#include <termios.h>#include <unistd.h>#include<unistd.h>#include<stdio.h>#include<sys/types.h>#include<sys/stat.h>#include <iostream>#include <cstring>using namespace std;int sendSerialPort(const unsigned char W_BUF[], int length) {int tty_fd = -1;int rv = -1;struct termios options;tty_fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY); //打开串口设备fcntl(tty_fd, F_SETFL, 0);if (tty_fd < 0) {printf("open tty failed:%s\n", strerror(errno));close(tty_fd);return -1;}printf("open devices sucessful!\n");memset(&options, 0, sizeof(options));rv = tcgetattr(tty_fd, &options); //获取原有的串口属性的配置if (rv != 0) {printf("tcgetattr() failed:%s\n", strerror(errno));close(tty_fd);return -1;}options.c_cflag |= (CLOCAL | CREAD); // CREAD 开启串行数据接收，CLOCAL并打开本地连接模式options.c_cflag &= ~CSIZE;// 先使用CSIZE做位屏蔽options.c_cflag |= CS8; //设置8位数据位options.c_cflag &= ~PARENB; //无校验位cfsetispeed(&options, B9600);cfsetospeed(&options, B9600);options.c_cflag &= ~CSTOPB;options.c_cc[VTIME] = 0;options.c_cc[VMIN] = 0;tcflush(tty_fd, TCIFLUSH);if ((tcsetattr(tty_fd, TCSANOW, &options)) != 0) {printf("tcsetattr failed:%s\n", strerror(errno));close(tty_fd);return -1;}std::cout << std::endl << "length= " << length << std::endl;rv = write(tty_fd, W_BUF, length);if(rv<=0) /* 出错了*/{if (errno == EINTR) /* 中断错误 我们继续写*/{close(tty_fd);printf("[SeanSend]error errno==EINTR continue\n");} else if (errno == EAGAIN) /* EAGAIN : Resource temporarily unavailable*/{sleep(1);//等待一秒，希望发送缓冲区能得到释放close(tty_fd);printf("[SeanSend]error errno==EAGAIN continue\n");} else /* 其他错误 没有办法,只好退了*/{printf("[SeanSend]ERROR: errno = %d, strerror = %s \n", errno, strerror(errno));return (-1);}}if (rv < 0) {printf("Write() error:%s\n", strerror(errno));close(tty_fd);return -1;}for (int i = 0; i < length; i++) {std::cout << std::hex << (int) W_BUF[i] << " ";}close(tty_fd);printf("\nWrite() successfully\n");return 0;}int main(int argc, char **argv) {//0xFD 0x00 0x07 0x01 0x01 0xD6 0xB1 0xD0 0xD0 0x9D //直行//0xFD 0x00 0x07 0x01 0x01 0xD7 0xF3 0xD7 0xAA 0xA3 //左转//0xFD 0x00 0x07 0x01 0x01 0xD3 0xD2 0xD7 0xAA 0x86 //右转const unsigned char data[][10] = {{0xFD, 0x00, 0x07, 0x01, 0x01, 0xD6, 0xB1, 0xD0, 0xD0, 0x9D},{0xFD, 0x00, 0x07, 0x01, 0x01, 0xD7, 0xF3, 0xD7, 0xAA, 0xA3},{0xFD, 0x00, 0x07, 0x01, 0x01, 0xD3, 0xD2, 0xD7, 0xAA, 0x86}};sendSerialPort(data[0], sizeof(data[0]));//测试return 0;}
测试方法
pi@raspberrypi:~/sxj731533730 $ g++ a.cpppi@raspberrypi:~/sxj731533730 $ ./a.outopen devices sucessful!length= 10fd 0 7 1 1 d6 b1 d0 d0 9dWrite() successfully
测试结果
第四步、测试超声波模块
引脚插线 我用的gpio14 和 15 引脚 ，超声波模块来自我买的锐志开发板带的超声波 哈哈
测试代码
import RPi.GPIO as GPIOimport timeTrig_Pin = 14Echo_Pin = 15GPIO.setmode(GPIO.BCM)GPIO.setup(Trig_Pin, GPIO.OUT, initial = GPIO.LOW)GPIO.setup(Echo_Pin, GPIO.IN)time.sleep(2)def checkdist():GPIO.output(Trig_Pin, GPIO.HIGH)time.sleep(0.000015)GPIO.output(Trig_Pin, GPIO.LOW)while not GPIO.input(Echo_Pin):passt1 = time.time()while GPIO.input(Echo_Pin):passt2 = time.time()return (t2-t1) *340/2try:while True:print('Distance:%0.2f m' % checkdist())time.sleep(3)except KeyboardInterrupt:GPIO.cleanup()
测试结果
c++ 测距代码 代码需要修改，在while循环那里，判断异常退出
#include <wiringPi.h>#include <stdio.h>#include <sys/time.h>#define Trig 14#define Echo 15void chaoShengBoInit(void){pinMode(Echo, INPUT); //设置端口为输入pinMode(Trig, OUTPUT); //设置端口为输出}float disMeasure(void){struct timeval tv0;struct timeval tv1; //timeval是time.h中的预定义结构体 其中包含两个一个是秒，一个是微秒/*struct timeval{time_t tv_sec; //Seconds.suseconds_t tv_usec; //Microseconds.};*/struct timeval tv2;struct timeval tv3;long start, stop;float dis;digitalWrite(Trig, LOW);delayMicroseconds(2);digitalWrite(Trig, HIGH);delayMicroseconds(10);//发出超声波脉冲digitalWrite(Trig, LOW);gettimeofday(&tv0, NULL); //获取当前时间 开 while(!(digitalRead(Echo) == 1)) {gettimeofday(&tv3, NULL); //获取当前时间 超时退出if(tv3.tv_usec-tv0.tv_usec>10)break;}gettimeofday(&tv1, NULL); //获取当前时间 开始接收到返回信号的时候while(!(digitalRead(Echo) == 0)){gettimeofday(&tv3, NULL); //获取当前时间 超时退出if(tv3.tv_usec-tv1.tv_usec>10)break;}gettimeofday(&tv2, NULL); //获取当前时间 最后接收到返回信号的时候start = tv1.tv_sec * 1000000 + tv1.tv_usec; //微秒级的时间stop = tv2.tv_sec * 1000000 + tv2.tv_usec;dis = (float)(stop - start) / 1000000 * 34000 / 2; //计算时间差求出距离return dis;}int main(void){float dis;printf("wiringPiSetup\n");if(wiringPiSetup() == -1){ //如果初始化失败，就输出错误信息 程序初始化时务必进行printf("setup wiringPi failed !");return 1;}chaoShengBoInit();while(1){dis = disMeasure();printf("distance = %0.2f cm\n",dis);delay(20);}return 0;}
编译命令和测试
pi@raspberrypi:~ $ g++ -g test.cpp -lwiringPipi@raspberrypi:~ $ ./a.out distance = 0.03 cmdistance = 0.02 cmdistance = 0.03 cmdistance = 0.03 cmdistance = 0.02 cmdistance = 0.03 cm
参考：
/tags/MtjaggysNDE2MDItYmxvZwO0O0OO0O0O.html
树莓派控制超声波模块_MHai的博客-CSDN博客_树莓派控制超声波
