pic16f877a drives the temperature and humidity sensor DHT11

admin · Posted on 11/25/2014 10:12:09 PM

[mw_shl_code=c,true]#include<pic.h> // Use 12M crystal oscillator
#include"12864.h"
#define uint unsigned int
#define uchar unsigned char
__CONFIG(FOSC_HS&WDTE_OFF&LVP_OFF);
uchar temp_valueH,hum_valueH,hum_valueL,temp_valueL,check;
uint delay_time;
void timer0_init()
{
TMR0=0;  First value
T0CS=0;  Select the clock source, which is 1/4 of the crystal oscillator;
T0SE=1; Clock source edge selection bits
PSA=0; Predivider allocation bits
PS0=0; PS1=0; PS2=0;  Pre-division selection bits
TMR0IF=0; The timer flag is clear 0
GIE=1;    Open the global interruption
TMR0IE=0; Timer 0 enabled
TMR0=236; The first value of the poem
}
void interrupt  timer0()
{
   if(TMR0IF)
   {
   TMR0IF=0; TMR0=235;
   delay_time--;
   }
}
void timer0_delay(uint delay_value)
{
delay_time=delay_value;
TMR0IE=1;
while(delay_time);
TMR0IE=0;
}
uchar Read_byte()
{
uchar i,temp,hum;
for(i=0; i<8; i++)
{
   while(! RC1);
   timer0_delay(2); Delay 20us
   temp=0;
   if(RC1){temp=1; while(RC1); }
   else{temp=0; }
   hum<<=1;
   hum|=temp;
  }
return(hum);
}
void Read_data()
{
uchar ckeck_value;
RC1=0;
timer0_delay(2500); The bus is pulled down by at least 18 MS
RC1=1;
timer0_delay(2); The bus is pulled up by the pull-up resistor and the host delay is 20us
TRISC1=1;    The host is set to input to judge the slave response signal
RC1=1;
  if(! RC1)
  {
while((! RC1)) // Determine whether the slave emits an 80us low response signal or not
{
NOP();
}
while(RC1) // Determine whether the slave emits a high level of 80us, and if so, it enters the data receiving state
{
NOP();
}
temp_valueH=Read_byte();
temp_valueL=Read_byte();
hum_valueH=Read_byte();
hum_valueL=Read_byte();
check=Read_byte();
ckeck_value=hum_valueL+hum_valueH+temp_valueL+temp_valueH;
  if(check==ckeck_value)
{
   Proce_num(0x84,temp_valueH);
   Proce_num(0x94,hum_valueH);
}
  }
  TRISC1=0;
  RC1=1;
}
void main()
{
  TRISB=0X00;
  lcdinit();
  timer0_init();
  while(1)
  {
Read_data();
  }
}[/mw_shl_code]

pic16f877a drives the temperature and humidity sensor DHT11

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