Contoh pemrograman AVR dgn sensor SHT11

Gambar Sckematik

Koneksi sht11 dgn AVR

Program AVR

/*********************************************

Project : The Sensirion SHT11 Humidity & Temperature Demo
Chip type : AT90S8535

Clock frequency : 4.000000 MHz
Memory model : Small
External SRAM size : 0
Data Stack size : 192

SHT1X Humidity and Temperature Sensor
AVR
Pin 1 GND
Pin 2 Data (PB0)
Pin 3 Serial Clock (PB1)
Pin 4 VDD (2.4V to 5.5V)

AVR PB2 – Heater On/Off Switch

Pin PB2 high – Heater On
Pin PB2 low – Heater Off

*********************************************/

#include <90s8535.h>
#include <stdio.h>
#include <delay.h>
#include <math.h>
// Alphanumeric LCD Module functions
#asm
.equ __lcd_port=0x1B
#endasm
#include <lcd.h>

// Declare your global variables here

typedef union
{ unsigned int i; float f;} value;

enum {TEMP,HUMI};

sfrb PINB = 0×16;
sfrb PORTB = 0×18;
sfrb DDRB = 0×17;

#define SHT_DATA_OUT DDRB.0
#define SHT_DATA_IN PINB.0
#define SHT_SCK PORTB.1
#define HEAT_SW PINB.2 // Heater On or Off
#define noACK 0
#define ACK 1
//adr command r/w
#define STATUS_REG_W 0×06 //000 0011 0
#define STATUS_REG_R 0×07 //000 0011 1
#define MEASURE_TEMP 0×03 //000 0001 1
#define MEASURE_HUMI 0×05 //000 0010 1
#define RESET 0x1e //000 1111 0

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

typedef struct{
unsigned char second; //enter the current time, date, month, and year
unsigned char minute;
unsigned char hour;
unsigned char date;
unsigned char month;
unsigned int year;
}time;
time t;

char lcd_buffer[33];

// Function Prototypes
interrupt [TIM2_OVF] void timer2_ovf_isr(void);
char not_leap(void);

//SHT Functions
char SHT_WriteByte(unsigned char value);
char SHT_ReadByte(unsigned char ack);
void s_transstart(void);
void s_connectionreset(void);
char s_softreset(void);
char s_measure(unsigned char *p_value, unsigned char *p_checksum, unsigned char mode);
void calc_sth11(float *p_humidity ,float *p_temperature);
float calc_dewpoint(float h,float t);

char s_write_statusreg(unsigned char *p_value);
char s_read_statusreg(unsigned char *p_value, unsigned char *p_checksum);

void main(void)
{
// Declare your local variables here

value humi_val, temp_val;
unsigned char error, checksum, status;
float dew_point;

t.hour = 23;
t.minute = 30;
t.second = 00;
t.date = 22;
t.month = 8;
t.year = 2003;

// Input/Output Ports initialization
// Port A initialization
// Func0=In Func1=In Func2=In Func3=In Func4=In Func5=In Func6=In Func7=In
// State0=T State1=T State2=T State3=T State4=T State5=T State6=T State7=T
PORTA=0×00;
DDRA=0×00;

// Port B initialization
// Func0=In Func1=In Func2=In Func3=In Func4=In Func5=In Func6=In Func7=In
// State0=T State1=T State2=T State3=T State4=T State5=T State6=T State7=T
PORTB=0×00;
DDRB=0×00;

// Port C initialization
// Func0=In Func1=In Func2=In Func3=In Func4=In Func5=In Func6=In Func7=In
// State0=T State1=T State2=T State3=T State4=T State5=T State6=T State7=T
PORTC=0×00;
DDRC=0×00;

// Port D initialization
// Func0=In Func1=In Func2=In Func3=In Func4=In Func5=Out Func6=In Func7=In
// State0=T State1=T State2=T State3=T State4=T State5=0 State6=T State7=T
PORTD=0×00;
DDRD=0×20;

// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: Timer 0 Stopped
TCCR0=0×00;
TCNT0=0×00;

// Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: Timer 1 Stopped
// Mode: Normal top=FFFFh
// OC1A output: Discon.
// OC1B output: Discon.
// Noise Canceler: Off
// Input Capture on Falling Edge
TCCR1A=0×00;
TCCR1B=0×00;
TCNT1H=0×00;
TCNT1L=0×00;
OCR1AH=0×00;
OCR1AL=0×00;
OCR1BH=0×00;
OCR1BL=0×00;

// Timer/Counter 2 initialization
// Clock source: TOSC1 pin
// Clock value: PCK2/128
// Mode: Normal top=FFh
// OC2 output: Disconnected
ASSR=0×08;
TCCR2=0×05;
TCNT2=0×00;
OCR2=0×00;

// External Interrupt(s) initialization
// INT0: Off
// INT1: Off
GIMSK=0×00;
MCUCR=0×00;

// Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=0×40;

// Analog Comparator initialization
// Analog Comparator: Off
// Analog Comparator Input Capture by Timer/Counter 1: Off
// Analog Comparator Output: Off
ACSR=0×80;

// LCD module initialization
lcd_init(20);
lcd_putsf(“- SHT11 Monitor -”);
//sprintf(lcd_buffer,”No. of Visitors = %d”,visitor);
//lcd_gotoxy(0,2);
//lcd_puts(lcd_buffer);

// Setup Sensibus Pins

PORTB.1 = 0; // ClockLow
DDRB.1 = 1; // SCK is an output

PORTB.0 = 0; // Always Zero
// Toggle DDRB.0 for Data

s_connectionreset();

/*
while (1)
{
s_transstart(); //transmission start

error+=SHT_WriteByte(MEASURE_TEMP); //send command to sensor

for (i=0;i<65535;i++)
if(SHT_DATA_IN==0) break; //wait until sensor has finished the measurement

if(SHT_DATA_IN) error+=1; //or timeout (~2 sec.) is reached

MSB =SHT_ReadByte(ACK); //read the first byte (MSB)
LSB =SHT_ReadByte(ACK); //read the second byte (LSB)
checksum =SHT_ReadByte(noACK); //read checksum

sprintf(lcd_buffer,”T= %u %u %u”,MSB,LSB,checksum);
lcd_gotoxy(0,1);
lcd_puts(lcd_buffer);

delay_ms(500);
}
*/

while (1)
{
error=0;
// Check heater pin
if(HEAT_SW)
status = 0b00000100; // Heater On
else status = 0b00000000; // Heater Off
s_write_statusreg(&status);

error+=s_measure((unsigned char*) &humi_val.i,&checksum,HUMI);
error+=s_measure((unsigned char*) &temp_val.i,&checksum,TEMP);
if(error!=0) s_connectionreset();
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
dew_point=calc_dewpoint(humi_val.f,temp_val.f); //calculate dew point
sprintf(lcd_buffer,”T:%5.1fC H:%5.1f%%”,temp_val.f,humi_val.f);
lcd_gotoxy(0,1);
lcd_puts(lcd_buffer);
if (HEAT_SW)
sprintf(lcd_buffer,”DP:%5.1fC Heat On “,dew_point);
else sprintf(lcd_buffer,”DP:%5.1fC Heat Off “,dew_point);
lcd_gotoxy(0,2);
lcd_puts(lcd_buffer);
}
// Global enable interrupts
#asm(“sei”)
delay_ms(1000);
#asm(“cli”)
}

}

// Timer 2 overflow interrupt service routine
interrupt [TIM2_OVF] void timer2_ovf_isr(void)
{
// Place your code here
if (++t.second==60) //keep track of time, date, month, and year
{
t.second=0;
if (++t.minute==60)
{
t.minute=0;
if (++t.hour==24)
{
t.hour=0;
if (++t.date==32)
{
t.month++;
t.date=1;
}
else if (t.date==31)
{
if ((t.month==4) || (t.month==6) || (t.month==9) || (t.month==11))
{
t.month++;
t.date=1;
}
}
else if (t.date==30)
{
if(t.month==2)
{
t.month++;
t.date=1;
}
}
else if (t.date==29)
{
if((t.month==2) && (not_leap()))
{
t.month++;
t.date=1;
}
}
if (t.month==13)
{
t.month=1;
t.year++;
}
}
}
}
sprintf(lcd_buffer,”%02d:%02d:%02d %02d/%02d/%04d”,t.hour, t.minute, t.second, t.date, t.month, t.year);
lcd_gotoxy(0,3);
lcd_puts(lcd_buffer);
}

char not_leap(void) //check for leap year
{
if (!(t.year%100))
return (char)(t.year%400);
else
return (char)(t.year%4);
}
//———————————————————————————-
// writes a byte on the Sensibus and checks the acknowledge
//———————————————————————————-
char SHT_WriteByte(unsigned char value)
{
unsigned char i,error=0;
for (i=0×80;i>0;i/=2) //shift bit for masking
{
if (i & value) SHT_DATA_OUT=0; //masking value with i , write to SENSI-BUS
else SHT_DATA_OUT=1;
SHT_SCK=1; //clk for SENSI-BUS
delay_us(5); //pulswith approx. 5 us
SHT_SCK=0;
}
SHT_DATA_OUT=0; //release DATA-line
SHT_SCK=1; //clk #9 for ack
error=SHT_DATA_IN; //check ack (DATA will be pulled down by SHT11)
SHT_SCK=0;
return error; //error=1 in case of no acknowledge
}

//———————————————————————————-
// reads a byte form the Sensibus and gives an acknowledge in case of “ack=1″
//———————————————————————————-
char SHT_ReadByte(unsigned char ack)
{
unsigned char i,val=0;
SHT_DATA_OUT=0; //release DATA-line
for (i=0×80;i>0;i/=2) //shift bit for masking
{
SHT_SCK=1; //clk for SENSI-BUS
if (SHT_DATA_IN) val=(val | i); //read bit
SHT_SCK=0;
}
SHT_DATA_OUT=ack; //in case of “ack==1″ pull down DATA-Line
SHT_SCK=1; //clk #9 for ack
delay_us(5); //pulswith approx. 5 us
SHT_SCK=0;
SHT_DATA_OUT=0; //release DATA-line
return val;
}

//———————————————————————————-
// generates a transmission start
// _____ ________
// DATA: |_______|
// ___ ___
// SCK : ___| |___| |______
//———————————————————————————-
void s_transstart(void)
{
SHT_DATA_OUT=0;
SHT_SCK=0; //Initial state
delay_us(1);
SHT_SCK=1;
delay_us(1);
SHT_DATA_OUT=1;
delay_us(1);
SHT_SCK=0;
delay_us(5);
SHT_SCK=1;
delay_us(1);
SHT_DATA_OUT=0;
delay_us(1);
SHT_SCK=0;
}

//———————————————————————————-
// communication reset: DATA-line=1 and at least 9 SCK cycles followed by transstart
// _____________________________________________________ ________
// DATA: |_______|
// _ _ _ _ _ _ _ _ _ ___ ___
// SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______| |___| |______
//———————————————————————————-

void s_connectionreset(void)
{
unsigned char i;
SHT_DATA_OUT=0; SHT_SCK=0; //Initial state
for(i=0;i<9;i++) //9 SCK cycles
{
SHT_SCK=1;
delay_us(1);
SHT_SCK=0;
}
s_transstart(); //transmission start
}

//———————————————————————————-
// resets the sensor by a softreset
//———————————————————————————-

char s_softreset(void)
{
unsigned char error=0;
s_connectionreset(); //reset communication
error+=SHT_WriteByte(RESET); //send RESET-command to sensor
return error; //error=1 in case of no response form the sensor
}

//———————————————————————————-
// makes a measurement (humidity/temperature) with checksum
//———————————————————————————-
char s_measure(unsigned char *p_value, unsigned char *p_checksum, unsigned char mode)
{
unsigned error=0;
unsigned int i;

s_transstart(); //transmission start
switch(mode){ //send command to sensor
case TEMP : error+=SHT_WriteByte(MEASURE_TEMP); break;
case HUMI : error+=SHT_WriteByte(MEASURE_HUMI); break;
default : break;
}
for (i=0;i<65535;i++) if(SHT_DATA_IN==0) break; //wait until sensor has finished the measurement
if(SHT_DATA_IN) error+=1; // or timeout (~2 sec.) is reached
*(p_value+1) =SHT_ReadByte(ACK); //read the first byte (MSB)
*(p_value) =SHT_ReadByte(ACK); //read the second byte (LSB)
*p_checksum =SHT_ReadByte(noACK); //read checksum
return error;
}

//—————————————————————————————-
// calculates temperature [°C] and humidity [%RH]
// input : humi [Ticks] (12 bit)
// temp [Ticks] (14 bit)
// output: humi [%RH]
// temp [°C]
//—————————————————————————————-

void calc_sth11(float *p_humidity ,float *p_temperature)
{

//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=*p_temperature*0.01 – 40; //calc. temperature from ticks to [°C]
rh_lin=C3*(*p_humidity)*(*p_humidity) + C2*(*p_humidity) + C1; //calc. humidity from ticks to [%RH]
rh_true=(t_C-25)*(T1+T2*(*p_humidity))+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]
}

//——————————————————————–
// calculates dew point
// input: humidity [%RH], temperature [°C]
// output: dew point [°C]
//——————————————————————–

float calc_dewpoint(float h,float t)
{
float logEx,dew_point;
logEx=0.66077+7.5*t/(237.3+t)+(log10(h)-2);
dew_point = (logEx – 0.66077)*237.3/(0.66077+7.5-logEx);
return dew_point;
}

//———————————————————————————-
// reads the status register with checksum (8-bit)
//———————————————————————————-
char s_read_statusreg(unsigned char *p_value, unsigned char *p_checksum)
{
unsigned char error=0;
s_transstart(); //transmission start
error=SHT_WriteByte(STATUS_REG_R); //send command to sensor
*p_value=SHT_ReadByte(ACK); //read status register (8-bit)
*p_checksum=SHT_ReadByte(noACK); //read checksum (8-bit)
return error; //error=1 in case of no response form the sensor
}

//———————————————————————————-
// writes the status register with checksum (8-bit)
//———————————————————————————-
char s_write_statusreg(unsigned char *p_value)
{
unsigned char error=0;
s_transstart(); //transmission start
error+=SHT_WriteByte(STATUS_REG_W);//send command to sensor
error+=SHT_WriteByte(*p_value); //send value of status register
return error; //error>=1 in case of no response form the sensor
}