嵌入式linux读取th10s温湿度传感器例程

硬件上接口为485
软件上有modbus协议
直接上代码

#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <termios.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//打开串口文件
static int open_uart(char *dev)
{
    
    
    long vdisable;
    int fd;

    fd = open(dev, O_RDWR|O_NOCTTY|O_NDELAY);//注意你的设备名
    if (-1 == fd)
    {
    
    
        perror("Can't Open Serial Port");
        return(-1);
    }

    return fd;
}

//配置串口参数 波特率 数据位 校验位 停止位
static int set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop)
{
    
    
    struct termios newtio, oldtio;

    if ( tcgetattr( fd,&oldtio) != 0)
    {
    
    
        printf("SetupSerial 1");
        return -1;
    }
    bzero( &newtio, sizeof( newtio ) );
    newtio.c_cflag |= CLOCAL | CREAD;
    newtio.c_cflag &= ~CSIZE;

    switch( nBits )
    {
    
    
		case 7:
			newtio.c_cflag |= CS7;
			break;
		case 8:
			newtio.c_cflag |= CS8;
			break;
    }

    switch( nEvent )
    {
    
    
		case 'O':
			newtio.c_cflag |= PARENB;
			newtio.c_cflag |= PARODD;
			newtio.c_iflag |= (INPCK | ISTRIP);
			break;
		case 'E':
			newtio.c_iflag |= (INPCK | ISTRIP);
			newtio.c_cflag |= PARENB;
			newtio.c_cflag &= ~PARODD;
			break;
		case 'N':
			newtio.c_cflag &= ~PARENB;
			break;
    }
    switch( nSpeed )
    {
    
    
		case 2400:
			cfsetispeed(&newtio, B2400);
			cfsetospeed(&newtio, B2400);
			break;
		case 4800:
			cfsetispeed(&newtio, B4800);
			cfsetospeed(&newtio, B4800);
			break;
		case 9600:
			cfsetispeed(&newtio, B9600);
			cfsetospeed(&newtio, B9600);
			break;
		case 115200:
			cfsetispeed(&newtio, B115200);
			cfsetospeed(&newtio, B115200);
			break;
		default:
			cfsetispeed(&newtio, B9600);
			cfsetospeed(&newtio, B9600);
			break;
    }
    if ( nStop == 1 )
    {
    
    
        newtio.c_cflag &= ~CSTOPB;
    }
    else if ( nStop == 2 )
    {
    
    
        newtio.c_cflag |= CSTOPB;
    }
    newtio.c_cc[VTIME] = 0;
    newtio.c_cc[VMIN]  = 0;
    tcflush(fd,TCIFLUSH);
    if ((tcsetattr(fd,TCSANOW,&newtio))!=0)
    {
    
    
        printf("com set error");
        return -1;
    }

    return 0;
}

static int fd;

int th10s_init()
{
    
    
	fd = open_uart("/dev/ttymxc2");//打开串口
	set_opt(fd,9600,8,'N',1);//配置串口参数 波特率 数据位8 校验无 停止位1位
	if(fd  != 0)
		printf("serial opened,wait rcv\n");//打印提示语
	else
		printf("serial opened fail\n");//打印提示语
	return 0;
}

static unsigned short MODBUS_CRC16(unsigned char *buf, unsigned short length)
{
    
    
	
	unsigned short i = 0, j = 0, tmp = 0;
	unsigned short crc = 0xFFFF;
	
	for(i = 0; i < length; i++)
	{
    
    
		crc = buf[i] ^ crc;
		for(j = 0; j < 8; j++)
		{
    
    
			tmp = crc & 0x0001;
			crc = crc >> 1;
			if(tmp)
				crc = crc ^ 0xA001;
		}
	}
	
	return crc << 8 | crc >> 8;
	
}

int th10s_read(float *t,float *h)
{
    
    
	unsigned char buffer[256]={
    
    0};
	unsigned int tmp = 0,crc;

	memset(buffer,0,256);//接收数组清零
	if (read(fd,buffer,sizeof(buffer)) > 8);//等待电脑串口调试助手发送数据
		if(buffer[0] == 0x01 && buffer[1] == 0x03 && buffer[2] == 0x04)
		{
    
    
			printf("rcv %x %x %x %x %x %x %x %x %x\n",buffer[0],buffer[1],buffer[2],buffer[3],buffer[4],buffer[5],buffer[6],buffer[7],buffer[8]);
	
			crc = MODBUS_CRC16(buffer, 7);
			if(buffer[7]|buffer[8] == crc)
			{
    
    
				*t = (float)(buffer[3] << 8 | buffer[4]) / 10.0;			
				*h = (float)(buffer[5] << 8 | buffer[6]) / 10.0;
			}
			return 0;
		}
	memset(buffer,0,256);//接收数组清零
	buffer[0] = 0x01;buffer[1] = 0x03;buffer[2] = 0x00;buffer[3] = 0x00;
	buffer[4] = 0x00;buffer[5] = 0x02;buffer[6] = 0x00;buffer[7] = 0x00;
	crc = MODBUS_CRC16(buffer, 6);
	buffer[6] = crc >> 8;
	buffer[7] = crc & 0xff;
	write(fd, buffer, 8);//将收到的数据发送回去
	printf("send %x %x %x %x %x %x %x %x %x\n",buffer[0],buffer[1],buffer[2],buffer[3],buffer[4],buffer[5],buffer[6],buffer[7],buffer[8]);
	
	return -1;
}

int tf_close(void)
{
    
    
	close(fd);//关闭串口

	return 0;
}