#include "IOSTM8S103F3.h"
//#include <intrins.h> //Keil library (is used for _nop()_ operation)
#include <math.h> //Keil library
#include <stdio.h> //Keil library
typedef union
{ unsigned int i;
float f;
} value;
//----------------------------------------------------------------------------------
// modul-var
//----------------------------------------------------------------------------------
enum {TEMP,HUMI};
#define DS_CLK_H() PB_ODR_ODR4=1
#define DS_CLK_L() PB_ODR_ODR4=0
#define DS_DATA_H() PB_ODR|= 0x20
#define DS_DATA_L() PB_ODR&=~0x20
#define DS_DATA_STATE PB_IDR_IDR5
#define SHT_DATA_IN {PB_DDR&=~ 0x20;PB_CR1&=~ 0x20;PB_CR2|=0x00;}
#define SHT_DATA_OUT {PB_DDR|=0x20;PB_CR1|=0x20;PB_CR2|=0x00;}//PB_CR1|=0x20
#define noACK 0
#define ACK 1
//adr command r/w
#define STATUS_REG_W 0x06 //000 0011 0
#define STATUS_REG_R 0x07 //000 0011 1
#define MEASURE_TEMP 0x03 //000 0001 1
#define MEASURE_HUMI 0x05 //000 0010 1
#define RESET 0x1e //000 1111 0
/*******************************************
函数名称：SHT_Init()
功 能：温湿度传感器IO初始化
参 数：无
返回值 ：无
********************************************/
void SHT_Init(void)
{
// P3SEL &=~(BIT6 + BIT7);
// P3OUT |= (BIT6 + BIT7);//SDA SCK输出
// SHT_DATA_HIGH;
// SHT_SCK_HIGH;
// SHTConnectionRst();//connection reset sequence
PB_DDR|=0x10;
PB_CR1|=0x10;
PB_CR2|=0x00;
SHT_DATA_OUT;
DS_DATA_H();
DS_CLK_H();
//s_connectionreset();
}
void Delay(long nCount)
{
/* Decrement nCount value */
while (nCount != 0)
{
nCount--;
}
}
//----------------------------------------------------------------------------------
char s_write_byte(unsigned char value)
//----------------------------------------------------------------------------------
// writes a byte on the Sensibus and checks the acknowledge
{
unsigned char i,error=0;
for (i=0x80;i>0;i/=2) //shift bit for masking
{ if (i & value) DS_DATA_H(); //masking value with i , write to SENSI-BUS
else DS_DATA_L();
DS_CLK_H(); //clk for SENSI-BUS
Delay(2);Delay(2);Delay(2); //pulswith approx. 5 us
DS_CLK_L();
}
DS_DATA_H(); //release DATA-line
SHT_DATA_IN;
DS_CLK_H(); //clk #9 for ack
error=DS_DATA_STATE; //check ack (DATA will be pulled down by SHT11)
DS_CLK_L();
Delay(2);
SHT_DATA_OUT;
return error; //error=1 in case of no acknowledge
}
//----------------------------------------------------------------------------------
char s_read_byte(unsigned char ack)
//----------------------------------------------------------------------------------
// reads a byte form the Sensibus and gives an acknowledge in case of "ack=1"
{
unsigned char i,val=0;
SHT_DATA_OUT;
DS_DATA_H(); //release DATA-line
SHT_DATA_IN;
for (i=0x80;i>0;i/=2) //shift bit for masking
{ DS_CLK_H(); //clk for SENSI-BUS
if (DS_DATA_STATE) val=(val | i); //read bit
DS_CLK_L();
}
SHT_DATA_OUT;
//DS_DATA_STATE=!ack; //in case of "ack==1" pull down DATA-Line
if(ack==1)
{
DS_DATA_L();
}
else
{
DS_DATA_H();
}
//if(ack==1) DS_DATA_L();
Delay(2);
DS_CLK_H(); //clk #9 for ack
Delay(2);Delay(2);Delay(2); //pulswith approx. 5 us
DS_CLK_L();
Delay(2);Delay(2);Delay(2);
//DS_DATA_H(); //release DATA-line
return val;
}
//----------------------------------------------------------------------------------
void s_transstart(void)
//----------------------------------------------------------------------------------
// generates a transmission start
// _____ ________
// DATA: |_______|
// ___ ___
// SCK : ___| |___| |______
{
DS_DATA_H();
DS_CLK_L(); //Initial state
Delay(2);
DS_CLK_H();
Delay(2);
DS_DATA_L();
Delay(2);
DS_CLK_L();
Delay(2);Delay(2);Delay(2);
DS_CLK_H();
Delay(2);
DS_DATA_H();
Delay(2);
DS_CLK_L();
}
//----------------------------------------------------------------------------------
void s_connectionreset(void)
//----------------------------------------------------------------------------------
// communication reset: DATA-line=1 and at least 9 SCK cycles followed by transstart
// _____________________________________________________ ________
// DATA: |_______|
// _ _ _ _ _ _ _ _ _ ___ ___
// SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______| |___| |______
{
unsigned char i;
DS_DATA_H(); DS_CLK_L(); //Initial state
for(i=0;i<9;i++) //9 SCK cycles
{ DS_CLK_H();
DS_CLK_L();
}
s_transstart(); //transmission start
}
//----------------------------------------------------------------------------------
char s_measure(unsigned char *p_value, unsigned char *p_checksum, unsigned char mode)
//----------------------------------------------------------------------------------
// makes a measurement (humidity/temperature) with checksum
{
unsigned error=0;
unsigned int i;
s_transstart(); //transmission start
switch(mode){ //send command to sensor
case TEMP : error+=s_write_byte(MEASURE_TEMP); break;
case HUMI : error+=s_write_byte(MEASURE_HUMI); break;
default : break;
}
SHT_DATA_IN;
for (i=0;i<65535;i++) if(DS_DATA_STATE==0) break; //wait until sensor has finished the measurement
if(DS_DATA_STATE) error+=1; // or timeout (~2 sec.) is reached
*(p_value) =s_read_byte(ACK); //read the first byte (MSB)
*(p_value+1)=s_read_byte(ACK); //read the second byte (LSB)
*p_checksum =s_read_byte(noACK); //read checksum
SHT_DATA_OUT;
return error;
}
//----------------------------------------------------------------------------------------
void calc_sth11(float *p_humidity ,float *p_temperature)
//----------------------------------------------------------------------------------------
// calculates temperature [ C] and humidity [%RH]
// input : humi [Ticks] (12 bit)
// temp [Ticks] (14 bit)
// output: humi [%RH]
// temp [ C]
{ const float C1=-4.0; // for 12 Bit
const float C2= 0.0405; // for 12 Bit
const float C3=-0.0000028; // for 12 Bit
const float T1=0.01; // for 14 Bit @ 5V
const float T2=0.00008; // for 14 Bit @ 5V
float rh=*p_humidity; // rh: Humidity [Ticks] 12 Bit
float t=*p_temperature; // t: Temperature [Ticks] 14 Bit
float rh_lin; // rh_lin: Humidity linear
float rh_true; // rh_true: Temperature compensated humidity
float t_C; // t_C : Temperature [ C]
//t_C=t*0.01 – 40; //calc. Temperature from ticks to [ C]
t_C=t*0.01;
t_C=t_C-40;
rh_lin=C3*rh*rh + C2*rh + C1; //calc. Humidity from ticks to [%RH]
rh_true=(t_C-25)*(T1+T2*rh)+rh_lin; //calc. Temperature compensated humidity [%RH]
if(rh_true>100)rh_true=100; //cut if the value is outside of
if(rh_true<0.1)rh_true=0.1; //the physical possible range
*p_temperature=t_C; //return temperature [ C]
*p_humidity=rh_true; //return humidity[%RH]
}
//----------------------------------------------------------------------------------
void main()
//----------------------------------------------------------------------------------
// sample program that shows how to use SHT11 functions
// 1. connection reset
// 2. measure humidity [ticks](12 bit) and temperature [ticks](14 bit)
// 3. calculate humidity [%RH] and temperature [ C]
// 4. calculate dew point [ C]
// 5. print temperature, humidity, dew point
{
value humi_val,temp_val;
unsigned char error,checksum;
unsigned int i;
SHT_Init();
s_connectionreset();
while(1)
{
//s_transstart();
//s_write_byte(0x03);
error=0;
error+=s_measure((unsigned char*) &humi_val.i,&checksum,HUMI); //measure humidity
error+=s_measure((unsigned char*) &temp_val.i,&checksum,TEMP); //measure temperature
if(error!=0) s_connectionreset(); //in case of an error: connection reset
else
{ humi_val.f=(float)humi_val.i; //converts integer to float
temp_val.f=(float)temp_val.i; //converts integer to float
calc_sth11(&humi_val.f,&temp_val.f); //calculate humidity, temperature
Delay(2);
}
printf("temp:%3.1f humi:%3.1f",temp_val.f,humi_val.f);
//----------wait approx. 0.8s to avoid heating up SHTxx------------------------------
for (i=0;i<40000;i++); //(be sure that the compiler doesn’t eliminate this line!)
//-----------------------------------------------------------------------------------
}
} |
