Humidity Sensor Help......

[rrb011270]

Mabuhay!

My code below will print to serial port monitor the linear relative humidity of a sensirion SHT15 humidity sensor.....

Unfortunately, it displays none to the monitor...

Anybody could check the code if I am missing something... or can provide me tips on how to improve the code....

Tenkyu

Code Below:

#include <18F452.h> //Microcontroller specific library, e.g. port definitions
//#device ICD=TRUE // with an ICD debugger
#fuses HS,NOLVP,NOWDT,PUT // high speed, no watch dog timer
#use delay (clock=20000000) // 20MHz clock
//#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7,ERRORS)
#use rs232(baud=115200, xmit=PIN_C6, rcv=PIN_C7)
#use fast_io(A)

#include <math.h>

#define DATA PIN_A0
#define SCK PIN_A1

#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


void sht1x_xmission_start()
/*{
output_high(DATA);
output_low(SCK);
delay_cycles(1);
output_high(SCK);
delay_cycles(1);
output_low(DATA);
delay_cycles(1);
output_low(SCK);
delay_cycles(1);
delay_cycles(1);
output_high(SCK);
delay_cycles(1);
output_high(DATA);
delay_cycles(1);
output_low(SCK);
}*/
{
output_high(DATA); // DATA=1;
output_low(SCK); // SCK=0;
delay_us(2); // _nop_();
output_high(SCK); // SCK=1;
delay_us(2); // _nop_();
output_low(DATA); // DATA=0;
delay_us(2); // _nop_();
output_low(SCK); // SCK=0;
delay_us(2); // _nop_();
delay_us(2); // _nop_();
delay_us(2); // _nop_();
output_high(SCK); // SCK=1;
delay_us(2); // _nop_();
output_high(DATA); // DATA=1;
delay_us(2); // _nop_();
output_low(SCK); // SCK=0;
delay_us(2);
}


void sht1x_connection_reset()
{
char i;

output_high(DATA);

for (i=0; i<9; i++)
{
output_high(SCK);
delay_us(2);
output_low(SCK);
delay_us(2);
}
sht1x_xmission_start();
}


main()
{
int i;
float rh_lin;
long value=0;
long temp;

float const C1 = -4.0;
float const C2 = 0.0405;
float const C3 = -0.0000028;


// connection reset
sht1x_connection_reset();

while (TRUE)
{
//start transmission
sht1x_xmission_start();

//measure humidity (write address & command)
for (i=128; i>0; i/=2)
{
if (i & MEASURE_HUMI) output_high(DATA);
else output_low(DATA);

output_high(SCK);
delay_us(2);
output_low(SCK);
}

set_tris_a(0x01);
output_high(SCK);
delay_us(2);
output_low(SCK);

//measure humidity (read data from SHT1x)
for (i=0; i<17; i++)
{
if (i=8)
{
output_high(SCK);
delay_us(2);
output_low(SCK);
}
else
{
value<<=1;
output_high(SCK);
temp = input(DATA);

if (temp) value|=1;

delay_us(2);
output_low(SCK);
}
}
output_low(SCK); // skip checksum
set_tris_a(0x00);

rh_lin = (C1+(C2*value)+(C3*value*value));
printf("\nRelative Humidity: %2.2f",rh_lin);
delay_ms(2000);
}
}

Need Help on this....

[Neutone]

A lot of people think of decimal and base 10 as one and the same. I like to think as interger and decimal as types of numbers that are independant of the base.

float const C1 = -4.0;
float const C2 = 0.0405;
float const C3 = -0.0000028;
rh_lin = (C1+(C2*value)+(C3*value*value));



is more better expressed as

const int8 C1 = 4;
const int16 const C2 = 2654; // 0.0405 * 2^16
const int8 const C3 = 46; // 0.0000028 * 2^24

int32 temp1;
int32 temp1;
temp1 = C2*value;
temp1 = temp1>>16; // temp * 2^-16
temp2=C3*value*value;
temp2=temp2>>24; // temp * 2^-24
rh_lin = (temp1-temp2-C1);

[rrb011270]

Mabuhay!

This is a working code for a sensirion SHT1x humidity/temperature sensor.

I share it to everybody.. maybe u can use it in your project.

===================================

#include <18F452.h> // MCU specific library
//#device ICD=TRUE // with an ICD debugger
#fuses HS,NOLVP,NOWDT,PUT // high speed, no watch dog timer
#use delay (clock=20000000) // 20MHz clock

//#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7,ERRORS)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)

//#include <math.h>

// set DATA to PortA1 and SCK to portA2
#define DATA PIN_A1
#define SCK PIN_A2

#define noACK 0
#define ACK 1

// SHT1x address=000 is currently supported
// SHT1x command code
//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

// constant use for SHT1x Humidity Measurement
#define C1 -4.0
#define C2 0.0405
#define C3 -0.0000028

// constant use for SHT1x Temperature Measurement
#define D1 -40.0
#define D2 0.01

// constant use for SHT1x True Humidity Measurement
#define T1 0.01
#define T2 0.00008


// SHT1x Transmission Start Sequence
void sht1x_xmission_start()
{
output_high(DATA);
output_low(SCK);
delay_us(2);
output_high(SCK);
delay_us(2);
output_low(DATA);
delay_us(2);
output_low(SCK);
delay_us(2);
delay_us(2);
delay_us(2);
output_high(SCK);
delay_us(2);
output_high(DATA);
delay_us(2);
output_low(SCK);
delay_us(2);
}


// SHT1x Connection Reset Sequence
void sht1x_connection_reset()
{
int i;

output_high(DATA);

for (i=0; i<9; i++)
{
output_high(SCK);
delay_us(2);
output_low(SCK);
delay_us(2);
}
sht1x_xmission_start();
}


// SHT1x Address & Command Mode with address=000
void sht1x_command_mode(int iMode)
{
int i;

for (i=128; i>0; i/=2)
{
if (i & iMode) output_high(DATA);
else output_low(DATA);

delay_us(2);
output_high(SCK);
delay_us(2);
output_low(SCK);
}

output_float(DATA);
delay_us(2);
output_high(SCK);
delay_us(2);
output_low(SCK);

// delay >11ms for 8-bit measurement
// delay >55ms for 12-bit measurement
// delay >210ms for 14-bit measurement
// before data read from SHT1x
delay_ms(250);
}


// SHT1x Soft Reset
// resets the interface, clears the status register to default values
// wait minimum 11ms before next command
void sht1x_soft_reset()
{
sht1x_connection_reset();
sht1x_command_mode(RESET);
}


// read data from SHT1x and store
long sht1x_read_data()
{
int i;
long lTmp;
long lVal1=0;
long lVal2=0;
long lValue;

// get MSB from SHT1x
for (i=0; i<8; i++)
{
lVal1<<=1;
output_high(SCK);
lTmp = input(DATA);
delay_us(2);
output_low(SCK);
delay_us(2);

if (lTmp) lVal1|=1;
}

// acknowledge routine
output_high(SCK);
output_low(DATA);
delay_us(2);
output_float(DATA);
output_low(SCK);
delay_us(2);

// get LSB from SHT1x
for (i=0; i<8; i++)
{
lVal2<<=1;
output_high(SCK);
lTmp = input(DATA);
delay_us(2);
output_low(SCK);
delay_us(2);

if (lTmp) lVal2|=1;
}

lValue = make16(lVal1,lVal2);
return(lValue);
}



// Main Program
main()
{
float fRh_lin;
float fRh_true;
float fTemp_true;

//long lValue_lin;
long lValue_rh;
long lValue_temp;

setup_adc_ports(NO_ANALOGS);

sht1x_connection_reset();


while (TRUE)
{
// delay >11ms before next command
delay_ms(12);

// start transmission
sht1x_xmission_start();

// measure temperature
sht1x_command_mode(MEASURE_TEMP);
lValue_temp = sht1x_read_data();
//printf("\nValue_temp: %lu ",lValue_temp);

fTemp_true = (D1+(D2*lValue_temp));

printf("\nTemperature: %2.2fC",fTemp_true);
//printf("\n");

// delay 11ms before next command
delay_ms(12);

// start transmission
sht1x_xmission_start();

// measure linear
sht1x_command_mode(MEASURE_HUMI);
lValue_rh = sht1x_read_data();
//printf("\nValue_lin: %lu ",lValue_lin);

fRh_lin = (C1+(C2*lValue_rh)+(C3*lValue_rh*lValue_rh));
fRh_true = (((fTemp_true-25)*(T1+(T2*lValue_rh)))+fRh_lin);

printf("\nLinear Relative Humidity: %2.2f%%",fRh_lin);
printf("\nRelative Humidity: %2.2f%%",fRh_true);
printf("\n");
delay_ms(2000);
}
}[/i]

[picprogrammer]

Nearly good, the program will not read the LSB. Change the sht1x_read_DATA() with this, the ack routine is changed.


// read DATA from SHT1x and store
long sht1x_read_DATA()
{
int i;
long lTmp;
long lVal1=0;
long lVal2=0;
long lValue;

// get MSB from SHT1x
for (i=0; i<8; i++)
{
lVal1<<=1;
output_high(SCK);
lTmp = input(DATA);
delay_us(2);
output_low(SCK);
delay_us(2);

if (lTmp) lVal1|=1;
}

// acknowledge routine
output_low(Data);
delay_us(2);
output_high(SCK);
delay_us(2);
output_low(SCK);
output_float(Data);
delay_us(2);

// get LSB from SHT1x
for (i=0; i<8; i++)
{
lVal2<<=1;
output_high(SCK);
lTmp = input(DATA);
delay_us(2);
output_low(SCK);
delay_us(2);

if (lTmp) lVal2|=1;
}

// acknowledge routine
output_high(Data);
delay_us(2);
output_high(SCK);
delay_us(2);
output_low(SCK);
output_float(Data);
delay_us(2);

lValue = make16(lVal1,lVal2);
return(lValue);
}