sht11.c

msp430与温湿度传感器sht1x的接口程序

#include <msp430x16x.h>
enum {TEMP,HUMI};

#define S_DATA_OUT P6DIR |= BIT6 //P6.5 OUT
#define S_DATA_IN P6DIR &=~BIT6 //P6.5 IN
#define S_DATA P6IN & BIT6 //P6.5 DATA
#define S_DATA_LOW P6OUT &=~BIT6
#define S_DATA_HIGH P6OUT |= BIT6
#define S_SCK_OUT P6DIR |= BIT7
#define S_SCK_LOW P6OUT &=~BIT7
#define S_SCK_HIGH P6OUT |= BIT7

#define noACK 0
#define ACK 1
//adr command r/w
#define MEASURE_TEMP 0x03 //000 0001 1
#define MEASURE_HUMI 0x05 //000 0010 1
#define MEASURE_STATUS 0x06 //000 0011 0

void delay(unsigned int k);
void s_transstart(void);
void s_connectionreset(void);
unsigned char s_write_byte(unsigned char value);
unsigned char s_read_byte(unsigned char ack);
void s_calc_sth11(void);
unsigned char s_measure(unsigned int *p_value, unsigned char mode);
void s_write_status();
void s_read_temp_and_humi(void);
unsigned int temperature,humidity;
float f_temperature,f_humidity;
unsigned char s_read_data(unsigned int *p_value);
unsigned char s_measure_cmd(unsigned char mode);
unsigned char s_error=0;
void main()
// sample program that shows how to use SHT11 functions
{ 
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
BCSCTL1 &=~XT2OFF;
BCSCTL2 |=SELM_2+SELS; 
s_connectionreset();
s_write_status();
while(1)
{ 
// s_read_temp_and_humi();
s_error=0;
s_error=s_measure_cmd(TEMP);
delay(60000);
s_error+=s_read_data(&temperature);
delay(60000);
s_error+=s_measure_cmd(HUMI);
delay(60000);
s_error+=s_read_data(&humidity);
delay(60000);
if(s_error!=0) 
s_connectionreset(); //in case of an error: connection reset
else
s_calc_sth11(); //calculate humidity, temperature
_NOP();
//----------wait approx. 0.8s to ××oid heating up SHTxx------------------------------ 

}
}
/******************************************************************************/
/* Temperature and humidity sensor function start */
/******************************************************************************/
// generates a tran××ission start 
// _____ ________
// DATA: |_______|
// ___ ___
// SCK : ___| |___| |______ 
void s_transstart(void)
{ 
S_DATA_HIGH; //Initial state
S_SCK_LOW;
S_SCK_HIGH;
S_DATA_LOW;
S_SCK_LOW;
S_SCK_HIGH; 
S_DATA_HIGH;
S_SCK_LOW; 
}
// communication reset: DATA-line=1 and at least 9 SCK cycles followed by transstart
// _____________________________________________________ ________
// DATA: |_______|
// _ _ _ _ _ _ _ _ _ ___ ___
// SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______| |___| |______
void s_connectionreset(void)
{ 
unsigned char i; 
S_DATA_OUT;
S_SCK_OUT;
S_DATA_HIGH; //Initial state
S_SCK_LOW; 
for(i=0;i<9;i++) //9 SCK cycles
{ 
S_SCK_HIGH;
S_SCK_LOW;
}
s_transstart(); //tran××ission start
}
// writes a byte on the Sensibus and checks the acknowledge 
unsigned char s_write_byte(unsigned char value)
{ 
unsigned char i,error=0; 
S_DATA_OUT;
for (i=0x80;i>0;i/=2) //shift bit for masking
{ 
if (i & value) S_DATA_HIGH; //masking value with i , write to SENSI-BUS
else S_DATA_LOW; 
S_SCK_HIGH; //clk for SENSI-BUS
S_SCK_LOW;
}
S_DATA_IN; 
S_SCK_HIGH; //clk #9 for ack 
error=S_DATA; //check ack (DATA will be pulled down by SHT11)
S_SCK_LOW; 
S_DATA_OUT; //release DATA-line
return error; //error=1 in case of no acknowledge
}
// reads a byte form the Sensibus and gives an acknowledge in case of "ack=1" 
unsigned char s_read_byte(unsigned char ack)
{ 
unsigned char i,val=0;
S_DATA_IN;
for (i=0x80;i>0;i/=2) //shift bit for masking
{ 
S_SCK_HIGH; //clk for SENSI-BUS
if (S_DATA) val=(val | i); //read bit 
S_SCK_LOW; 
}
S_DATA_OUT;
if(ack)
S_DATA_LOW;
else
S_DATA_HIGH; //in case of "ack==1" pull down DATA-Line
S_SCK_HIGH; //clk #9 for ack
S_SCK_LOW; //release DATA-line
return val;
} 
/*Write status register:12bit humi,14bit temp*/
void s_write_status(void)
{
s_connectionreset();
s_write_byte(MEASURE_STATUS);
s_write_byte(0x00); 
}
// makes a measurement (humidity/temperature)
unsigned char s_measure(unsigned int *p_value,unsigned char mode)
{ 
unsigned char error=0;
unsigned int i;

s_transstart(); //tran××ission start
if(mode==TEMP) //send command to sensor
error+=s_write_byte(MEASURE_TEMP);
else
error+=s_write_byte(MEASURE_HUMI);
S_DATA_IN;
for (i=0;i<65535;i++) if(S_DATA==0) break; //wait until sensor has finished the measurement
if(S_DATA) error+=1; // or timeout (~1 sec.) is reached
*p_value =s_read_byte(ACK); //read the first byte (MSB)
*p_value = (*p_value)<<8;
(*p_value) +=s_read_byte(noACK); //read the second byte (LSB)
return error;
}
/***mode:TEMP,HUMI***/
unsigned char s_measure_cmd(unsigned char mode)
{
unsigned char error=0;
s_transstart();
if(mode==TEMP) //send command to sensor
error+=s_write_byte(MEASURE_TEMP);
else
error+=s_write_byte(MEASURE_HUMI);
S_DATA_IN;
return error;
}
unsigned char s_read_data(unsigned int *p_value)
{
if(S_DATA)
return 1;
else
{
*p_value =s_read_byte(ACK); //read the first byte (MSB)
*p_value = (*p_value)<<8;
(*p_value) +=s_read_byte(noACK); //read the second byte (LSB)
return 0;
}
}
// calculates temperature [懊] and humidity [%RH] 
// input : humi [Ticks] (8 bit) 
// temp [Ticks] (12 bit)
// output: humi [%RH]
// temp [懊]
/*void s_calc_sth11(void)
{ 
float rh=humidity; // rh: Humidity
float t=temperature; // t: Temperature

t=t*0.04 - 39.64; //calc. temperature from ticks to [℃]
rh=(0.648-0.00072*rh)*rh -4.0; //calc. humidity from ticks to [%RH]
rh=(t-25)*(0.01+0.00128*humidity)+rh; //calc. temperature compensated humidity [%RH]
f_temperature=t;
temperature=t; //return temperature [℃]
f_humidity=rh;
humidity=rh; //return humidity[%RH]
if((t-temperature)>=0.5)
temperature+=1;
if((rh-humidity)>=0.5)
humidity+=1;
if(humidity>100) humidity=100; //cut if the value is outside of 
if(humidity<1) humidity=1; //the physical possi××e range
}*/
// calculates temperature [懊] and humidity [%RH] 
// input : humi [Ticks] (12 bit) 
// temp [Ticks] (14 bit)
// output: humi [%RH]
// temp [懊]
void s_calc_sth11(void)
{ 
float rh; // rh: Humidity
float t; // t: Temperature
float ttt;
if(temperature>7000) 
ttt=temperature-7000;
else
ttt=7000-temperature;
t=temperature*0.01 - 39.64-0.00000002*ttt*ttt; //calc. temperature from ticks to [℃]
rh=(0.0405-0.0000028*humidity)*humidity -4.0; //calc. humidity from ticks to [%RH]
rh=(t-25)*(0.01+0.00008*humidity)+rh; //calc. temperature compensated humidity [%RH]
f_temperature=t;
temperature=t; //return temperature [℃]
f_humidity=rh;
humidity=rh; //return humidity[%RH]
if((t-temperature)>=0.5)
temperature+=1;
if((rh-humidity)>=0.5)
humidity+=1;
if(humidity>100) humidity=100; //cut if the value is outside of 
if(humidity<1) humidity=1; //the physical possi××e range
}
// measure humidity [%RH](8 bit) and temperature [℃](12 bit)
void s_read_temp_and_humi(void)
{
unsigned char error=1;
while(error)
{
error=0;
error+=s_measure(&humidity,HUMI); //measure humidity
error+=s_measure(&temperature,TEMP); //measure temperature
if(error!=0) 
s_connectionreset(); //in case of an error: connection reset
else
s_calc_sth11(); //calculate humidity, temperature
}
}
/******************************************************************************/
/* Temperature and humidity sensor function END */
/******************************************************************************/
void delay(unsigned int k)
{
unsigned int ktemp;
for(ktemp=0;ktemp<k;ktemp++);
}