shtxx.c

SHT11温湿传感器+AVR 单片机MEGA16程序

#include "shtxx.h"

void shtxx_init(void)
{
	shtxx_temp = shtxx_humi = 0;
	SHTXX_SCK_LOW();
	SHTXX_DAT_1();
	shtxx_reconnect();
}

void shtxx_reconnect(void)
{
	SHTXX_DAT_1();
	SHTXX_SCK_LOW();
	for(uint8 i=0; i<9; i++)
	{
		SHTXX_SCK_HIGH(); SHTXX_SCK_LOW();
	}
	SHTXX_START();
}

uint8 shtxx_softrst(void)
{
	uint8 error = 0;
	shtxx_reconnect();
	error += shtxx_write_byte(SHTXX_SOFT_RST);
	return error;
}

//写命令函数
//参数：命令类型
//返回：0成功，1失败
uint8 shtxx_write_byte(uint8 cmd)
{
	uint8 ack;
	for (uint8 i=8; i>0; i--)
	{
		if (BITCHK(cmd, (i-1)))		//trans '1' 
		{
			SHTXX_DAT_1();	
			SHTXX_SCK_HIGH(); SHTXX_SCK_LOW();
		}	
		else 						//trans '0'
		{
			SHTXX_DAT_0();						 
			SHTXX_SCK_HIGH(); SHTXX_SCK_LOW();
		}
	}
	//SHTxx 会以下述方式表示已正确地接收到指令：
	//在第8 个SCK 时钟的下降沿之后，将DATA 下拉为低电平（ACK 位）。
	//在第9 个SCK 时钟的下降沿之后，释放DATA（恢复高电平）。
	BITCLR(SHTXX_DAT_DDR, SHTXX_DAT_BIT);
	SHTXX_SCK_HIGH();
	ack = BITCHK(SHTXX_DAT_PIN, SHTXX_DAT_BIT);
	SHTXX_SCK_LOW();
	return ack;
}

uint8 shtxx_read_byte(uint8 dat_crc)
{
	uint8 dat8 = 0;
	for (uint8 i=8; i>0; i--)
	{
		BITCLR(SHTXX_DAT_DDR, SHTXX_DAT_BIT);
		c4680504cSHTXX_SCK_HIGH();
		if (BITCHK(SHTXX_DAT_PIN, SHTXX_DAT_BIT)) 
			BITSET(dat8, (i-1));
		SHTXX_SCK_LOW();
	}
	
	if (dat_crc)
	{
		SHTXX_DAT_0();
		SHTXX_SCK_HIGH(); SHTXX_SCK_LOW();
	}
	else
	{
		SHTXX_DAT_1();
		SHTXX_SCK_HIGH(); SHTXX_SCK_LOW();
	}
	SHTXX_DAT_1();	
	
	return dat8;
}

int8 shtxx_measure(uint8 mode)
{
	uint8 error = 0;
	
	SHTXX_START();	
	switch (mode)
	{
		case SHTXX_MODE_TEMP:
			error = shtxx_write_byte(SHTXX_CMD_TEMPTURE);
			for(uint16 i=0; i<65535; i++)
			{	
				_delay_us(5);
				BITCLR(SHTXX_DAT_DDR, SHTXX_DAT_BIT); 
				if (!(BITCHK(SHTXX_DAT_PIN, SHTXX_DAT_BIT))) break;
			}
			BITCLR(SHTXX_DAT_DDR, SHTXX_DAT_BIT); 
			if (BITCHK(SHTXX_DAT_PIN, SHTXX_DAT_BIT)) error += 1;
						
			shtxx_temp = shtxx_read_byte(1);
			shtxx_temp = (shtxx_temp << 8) + shtxx_read_byte(1);
			shtxx_crc = shtxx_read_byte(0);	
			break;
		case SHTXX_MODE_HUMI:
			error = shtxx_write_byte(SHTXX_CMD_HUMIDITY);
			for(uint16 i=0; i<65535; i++)
			{	
				_delay_us(5);
				BITCLR(SHTXX_DAT_DDR, SHTXX_DAT_BIT); 
				if (!(BITCHK(SHTXX_DAT_PIN, SHTXX_DAT_BIT))) break;
			}
			BITCLR(SHTXX_DAT_DDR, SHTXX_DAT_BIT); 
			if (BITCHK(SHTXX_DAT_PIN, SHTXX_DAT_BIT)) error += 1;
			shtxx_humi = shtxx_read_byte(1);
			shtxx_humi = (shtxx_humi<<8) + shtxx_read_byte(1);			
			shtxx_crc = shtxx_read_byte(0);		
			break;
		default:
			break;
	}

	return error;
}

void shtxx_calc(void)
{
	uint32 rh_line = 0;
	//所有湿度常量放大10000000
	const uint32 C1 = 40000000;
	const uint32 C2 = 405000;
	const uint32 C3 = 28;
	const uint32 T1 = 100000;
	const uint32 T2 = 8000;	
	
	//温度常量放大100
	t_c = shtxx_temp - 4000;	//结果除以100
	
	rh_line = C2*shtxx_humi - C3*shtxx_humi*shtxx_humi - C1;
	rh_true = (t_c/100-25)*(T1+T2*shtxx_humi) + rh_line;
	
	if (rh_true>1000000000) rh_true = 1000000000; //cut if the value is outside of
	if (rh_true<1000000) rh_true = 1000000; //the physical possible range
}

void hex_bcd(uint32 hex32)
{
	memset(bcd32, '\0', 10);
	while (hex32 >= 1000000000)		//
	{
		bcd32[9]++;
		hex32 = hex32 - 1000000000;
	}	  
		   
	while (hex32 >= 100000000)		//
	{
		bcd32[8]++;
		hex32 = hex32 - 100000000;
	}
	
	while (hex32 >= 10000000)		//
	{
		bcd32[7]++;
		hex32 = hex32 - 10000000;
	}
	
	while (hex32 >= 1000000)		//
	{
		bcd32[6]++;
		hex32 = hex32 - 1000000;
	}
	
	while (hex32 >= 100000)			//
	{
		bcd32[5]++;
		hex32 = hex32 - 100000;
	}
	
	while (hex32 >= 10000)			//
	{
		bcd32[4]++;
		hex32 = hex32 - 10000;
	}	
	
	while (hex32 >= 1000)			//
	{
		bcd32[3]++;
		hex32 = hex32 - 1000;
	}	
	
	while (hex32 >= 100)			//
	{
		bcd32[2]++;
		hex32 = hex32 - 100;
	}	
	
	while (hex32 >= 10)				//
	{
		bcd32[1]++;
		hex32 = hex32 - 10;
	}
	
	bcd32[0] = hex32;
}

void shtxx_disp(void)
{
	if (!shtxx_measure(SHTXX_MODE_TEMP))
	{
		shtxx_calc();
		hex_bcd(t_c);
		lcd_print_str(2, 1, "温度: ");
		
		if(bcd32[4] != 0)
			lcd_write_dat(bcd32[4]+0x30);
		lcd_write_dat(bcd32[3]+0x30);
		lcd_write_dat(bcd32[2]+0x30);
		lcd_write_dat('.');
		lcd_write_dat(bcd32[1]+0x30);
		lcd_write_dat(bcd32[0]+0x30);
	}
	if (!shtxx_measure(SHTXX_MODE_HUMI))
	{
		shtxx_calc();
		hex_bcd(rh_true);
		lcd_print_str(3, 1, "湿度: ");
		
		if(bcd32[9] != 0)
			lcd_write_dat(bcd32[9]+0x30);
		lcd_write_dat(bcd32[8]+0x30);
		lcd_write_dat(bcd32[7]+0x30);
		lcd_write_dat('.');
		lcd_write_dat(bcd32[6]+0x30);
		lcd_write_dat(bcd32[5]+0x30);
	}
}