pic16f876a.c

PIC 16F876A-4MHz 和STH11, data pin =PortA.0, sck pin =PortC.3.

//////////////////////////SHT11.H///////////////////////////////////////////////
// //
// Driver file for SHT11 Temperature & Humidity Sensor //
// //
// ***** To initialise SHT11 sensor upon power up ***** //
// //
// Function : sht_init() //
// Return : none //
// //
// //
// ***** To measure and caluculate SHT11 temp & real RH ***** //
// //
// Function : sht_rd (temp, truehumid) //
// Return : temperature & true humidity in float values //
//
typedef union
{ unsigned int i;
float f;
} value;

enum {TEMP,HUMI};

#define DATA PORTA.F0 //= 0x00 // portA bit 0
#define SCK PORTC.F3 //= 0x01 // portA bit1
#define PORT_COND TRISA.F0
#define TEMP 0
#define HUMI 1
#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

char* Out_temp()
{
char str[]="Temp:" absolute MEMORY_ADDRESS;
return str;
}

char* Out_humi()
{
char str[]="Humi:" absolute MEMORY_ADDRESS;
return str;
}
void init_LCD(){

TRISB = 0; // PORTB is output
Lcd_Custom_Config(&PORTB,7,6,5,4,&PORTB,2,0,3); // Initialize LCD on PORTB
Lcd_Custom_Cmd(LCD_CLEAR) ; // Clear display
Lcd_Custom_Cmd(Lcd_CURSOR_OFF); // Turn on cursor
Delay_ms(1000);

}

void initialize(void){
//ADCON1 = 0xF7; // Configure all pins as digital I/O
TRISB = 0x00; // PORTB is output
PORTB = 0x00;
// PORTB = 0xF9;
TRISA = 0x00; // PORTA is output
PORTA = 0x00;

TRISC = 0x00; // PORTC is output
PORTC = 0x00; // Set PORTC to 00
// Soft_Uart_Init(PORTB, 5, 0, 9600, 0);
// Usart_Init(9600);
}

char s_write_byte(unsigned char value)
//----------------------------------------------------------------------------------
// writes a byte on the Sensibus and checks the acknowledge
{
unsigned char i=0;
unsigned char error=0;

PORT_COND = 0; //SHT11 WRITE

for (i=0x80;i>0;i/=2) //shift bit for masking
{
if (i & value) DATA = 1; //masking value with i , write to SENSI-BUS

else DATA=0;
SCK=1; //clk for SENSI-BUS
Delay_us(5); //pulswith approx. 5 us
SCK=0;
}
DATA=1; //release DATA-line
SCK=1; //clk #9 for ack
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
{ SCK=1; //clk for SENSI-BUS
if (DATA) val=(val | i); //read bit
SCK=0;
}
DATA=!ack; //in case of "ack==1" pull down DATA-Line
SCK=1; //clk #9 for ack
Delay_us(5); //pulswith approx. 5 us
SCK=0;
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(5);
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 c;

PORT_COND = 0; //SHT11 WRITE

DATA=1; SCK=0; //Initial state
for(c=0;c<9;c++) //9 SCK cycles
{ SCK=1;
SCK=0;
}
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
*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;
case HUMI : error+=s_write_byte(MEASURE_HUMI); break;
default : break;
}

PORT_COND = 1; //SHT11 READ

for (i=0;i<65535;i++) if(DATA==0) break; //wait until sensor has finished the measurement
if(DATA) error+=1; // or timeout (~2 sec.) is reached
*(p_value+1) =s_read_byte(ACK); //read the first byte (MSB)
*(p_value)=s_read_byte(ACK); //read the second byte (LSB)
*p_checksum =s_read_byte(noACK); //read checksum
return error;
}

//----------------------------------------------------------------------------------
/*void init_uart()
//----------------------------------------------------------------------------------
//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;

/*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; */
}
//----------------------------------------------------------------------------------
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

{
initialize(); ///Initialize parameters
Delay_ms(2000);
//TRISA = 0;
//TRISB = 0;
{
value humi_val,temp_val;
float dew_point;
unsigned char error,checksum;
unsigned int i;

char temp[13];
char humi[13];

init_LCD();

/* init_uart(); */
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)
{
/* char *text = "calc error";
Lcd_Custom_Out(1,2,text);
Delay_ms(1000); // Print text at LCD
*/
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
// printf("temp:%5.1fC humi:%5.1f%% dew point:%5.1fC\n",temp_val.f,humi_val.f,dew_point);
//send final data to serial interface (UART)
Lcd_Custom_Out(1,1,Out_temp());
Lcd_Custom_Out(2,1,Out_humi());

FloatToStr(temp_val.f, temp);
Lcd_Custom_Out(1,6,temp);

FloatToStr(humi_val.f, humi);
Lcd_Custom_Out(2,6,humi);

}
//----------wait approx. 0.8s to avoid heating up SHTxx------------------------------

delay_ms(1000);//for (i=0;i<40000;i++); //(be sure that the compiler doesn't eliminate this line!)
//-----------------------------------------------------------------------------------
}
}
}