Please help me.
I desperately disappointed with SHT75.
I need the 0.01 resolution and i checked nearly all of programs about SHT on this forum and i have worked for several days but still no response.
My microchip is 18f452,my clock is 8M.
My LCD works properly and i connect sht as its datasheet.DATA->RB2 with pull-up.SCK->RB1 and two others to +5v and GND.
Thanks in advance.
This is my program but nothing shown on LCD.
Code: Select all
/*******************************************************************************
Filename : SHT11_testing.c
Author : LIAU WEI CHUN
Email : wcl14u@gmail.com
Revision : Demo Revised 1.0b
Date : 29 Feb 2008
Compiled by: Mikro C v8.0.0.0
PIC 16F877A~4MHz.
History : Changes made to the original Keil's lib.
- Reconfigure data pin, sck pin & data port condition.
- Added data port condition: input/output
- _nop_() function -> Delay_us()
*******************************************************************************/
typedef union
{ unsigned int i;
float f;
} value;
//------------------------------------------------------------------------------
// modul-var
//------------------------------------------------------------------------------
//enum {TEMP,HUMI};
//#include "initlcd.h"
#define TEMP 0
#define HUMI 1
#define PORT_COND TRISB.F2 //data port condition: input/output
#define DATA PORTB.F2 //SHT11 DATA pin
#define SCK PORTB.F1 //STH11 SCK pin
#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
#define MEMORY_ADDRESS 0xA0
/************************************************************
Filename : initlcd.c
Description: Initializations of LCD & Sound.
************************************************************/
void Initlcd(void)
{
ADCON1 = 0xff;
PORTA = 0x00; //initialize/clear PORTA
PORTB = 0x00; //initialize PORTB
PORTC = 0x00; //initialize PORTC
PORTD = 0x00; //initialize PORTD
TRISA = 0; //PORTA = output.
TRISB = 0;
TRISC = 0;
TRISD = 0; //PORTD = output.
TRISE = 0; //PORTE = output.
//Lcd_Config(&PORTD, 0, 1, 7, 5, 4, 3, 2);
Lcd_Init(&PORTD);
Lcd_Cmd(LCD_CLEAR); // Clear display
Lcd_Cmd(LCD_CURSOR_OFF); // Turn cursor off
}
char* Out_temp()
{
char str[]="Temp:" absolute MEMORY_ADDRESS;
return str;
}
char* Out_humi()
{
char str[]="Humi:" absolute MEMORY_ADDRESS;
return str;
}
//------------------------------------------------------------------------------
char s_write_byte(unsigned char value)
//------------------------------------------------------------------------------
// writes a byte on the Sensibus and checks the acknowledge
{
unsigned char i,error=0;
PORT_COND = 0; //SHT11 WRITE
for (i=0x80;i>0;i/=2) //shift bit for masking
{
Delay_us(2);
if (i & value)
DATA=1; //masking value with i , write to SENSI-BUS
else
DATA=0;
SCK=1; //clk for SENSI-BUS
Delay_us(2); //pulswith approx. 5 us
SCK=0;
}
DATA=1; //release DATA-line
PORT_COND = 1; //SHT11 READ
Delay_us(2);
SCK=1; //clk #9 for ack
Delay_us(2);
error = DATA; //check ack (DATA will be pulled down by SHT11)
SCK=0;
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;
PORT_COND = 1; //SHT11 READ
DATA=1; //release DATA-line
for (i=0x80;i>0;i/=2) //shift bit for masking
{
Delay_us(2);
SCK=1; //clk for SENSI-BUS
if (DATA) val=(val | i); //read bit
Delay_us(2);
SCK=0;
}
Delay_us(2);
PORT_COND = 0; //SHT11 WRITE
Delay_us(2);
DATA=!ack; //in case of "ack==1" pull down DATA-Line
SCK=1; //clk #9 for ack
Delay_us(2); //pulswith approx. 5 us
SCK=0;
Delay_us(2);
DATA=1; //release DATA-line
return val;
}
//----------------------------------------------------------------------------------
void s_transstart(void)
//----------------------------------------------------------------------------------
// generates a transmission start
// _____ ________
// DATA: |_______|
// ___ ___
// SCK : ___| |___| |______
{
PORT_COND = 0; //SHT11 WRITE
DATA=1;
SCK=0; //Initial state
Delay_us(2);
SCK=1;
Delay_us(2);
DATA=0;
Delay_us(2);
SCK=0;
Delay_us(2);
SCK=1;
Delay_us(2);
DATA=1;
Delay_us(2);
SCK=0;
}
//----------------------------------------------------------------------------------
void s_connectionreset(void)
//----------------------------------------------------------------------------------
// communication reset: DATA-line=1 and at least 9 SCK cycles followed by transstart
// _____________________________________________________ ________
// DATA: |_______|
// _ _ _ _ _ _ _ _ _ ___ ___
// SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______| |___| |______
{
unsigned char i;
PORT_COND = 0; //SHT11 WRITE
DATA=1; SCK=0; //Initial state
for(i=0;i<9;i++) //9 SCK cycles
{
Delay_us(2);
SCK=1;
Delay_us(2);
SCK=0;
}
Delay_us(2);
s_transstart(); //transmission start
}
//----------------------------------------------------------------------------------
char s_softreset(void)
//----------------------------------------------------------------------------------
// resets the sensor by a softreset
{
unsigned char error=0;
s_connectionreset(); //reset communication
error+=s_write_byte(RESET); //send RESET-command to sensor
return error; //error=1 in case of no response form the sensor
}
//----------------------------------------------------------------------------------
char s_read_statusreg(unsigned char *p_value, unsigned char *p_checksum)
//----------------------------------------------------------------------------------
// reads the status register with checksum (8-bit)
{
unsigned char error=0;
s_transstart(); //transmission start
error=s_write_byte(STATUS_REG_R); //send command to sensor
//Delay_us(100);
*p_value=s_read_byte(ACK); //read status register (8-bit)
*p_checksum=s_read_byte(noACK); //read checksum (8-bit)
return error; //error=1 in case of no response form the sensor
}
//----------------------------------------------------------------------------------
char s_write_statusreg(unsigned char *p_value)
//----------------------------------------------------------------------------------
// writes the status register with checksum (8-bit)
{
unsigned char error=0;
s_transstart(); //transmission start
error+=s_write_byte(STATUS_REG_W);//send command to sensor
error+=s_write_byte(*p_value); //send value of status register
return error; //error>=1 in case of no response form the sensor
}
//----------------------------------------------------------------------------------
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; //temp
case HUMI : error+=s_write_byte(MEASURE_HUMI); break; //humidity
default : break;
}
PORT_COND = 1; //SHT11 READ
for (i = 0; i < 65535 && DATA; i++) Delay_us(10); //wait until sensor has finished the measurement
//while (DATA == 1) Delay_us(1);
if(DATA) error+=1; // or timeout (~2 sec.) is reached
*(p_value+1)=s_read_byte(ACK); //read the second byte (LSB)
*(p_value) =s_read_byte(ACK); //read the first byte (MSB)
*p_checksum =s_read_byte(noACK); //read checksum
return error;
}
/*
//----------------------------------------------------------------------------------
void init_uart()
//----------------------------------------------------------------------------------
// Initializes the UART so the final data can be sent away, e.g. to a PC
//9600 bps @ 11.059 MHz
{ SCON = 0x52;
TMOD = 0x20;
TCON = 0x69;
TH1 = 0xfd;
}
*/
//----------------------------------------------------------------------------------------
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]
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]
}
//--------------------------------------------------------------------
float calc_dewpoint(float h,float t)
//--------------------------------------------------------------------
// calculates dew point
// input: humidity [%RH], temperature [C]
// output: dew point [C]
{ float k,dew_point ;
k = (log10(h)-2)/0.4343 + (17.62*t)/(243.12+t);
dew_point = 243.12*k/(17.62-k);
return dew_point;
}
//----------------------------------------------------------------------------------
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;
float dew_point;
unsigned char error,checksum;
//unsigned int i;
char temp[13];
char humi[13];
Initlcd(); //Initialize LCD
s_connectionreset();
Delay_ms(20);
while(1)
{
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
dew_point=calc_dewpoint(humi_val.f,temp_val.f); //calculate dew point
//send final data to serial interface (UART)
Lcd_Out(1,1,Out_temp());
Lcd_Out(2,1,Out_humi());
FloatToStr(temp_val.f, temp);
Lcd_Out(1,6,temp);
FloatToStr(humi_val.f, humi);
Lcd_Out(2,6,humi);
}
//----------wait approx. 0.8s to avoid heating up SHTxx----------------------
//-----------------------------------------------------------------------------------
Delay_ms(1000);
}
}