Hello friends,
I'm compilited this code for interface BBB with DHT11(temperature-humidity
sensor) this code is compiled and run successfully but OUTPUT
is
*0'c temperature - 0% humidity ....Plz *, find error this code...
*Code-#include <stdio.h>#include <stdlib.h>#include <string.h>#include
<time.h>#include <stdint.h>#include <sys/time.h>#include <unistd.h>#define
MAXTIMINGS 85#define DHTPIN 48int dht11_dat[5] = { 0, 0, 0, 0, 0
};int readpin(int pinnum);void setDirection(int pin, int dir);void
writepin(int pinnum, int value);void pauseSec(int sec);void
pauseNanoSec(long nano);void setDirection(int pin, int dir) {
FILE *fpin, *fpinDir; char pinDir[50]; fpin =
fopen("/sys/class/gpio/export", "w"); fprintf(fpin, "%i",
pin); fflush(fpin); sprintf(pinDir,
"/sys/class/gpio/gpio%i/direction", pin); fpinDir = fopen(pinDir,
"w"); fprintf(fpinDir, dir ? "in" : "out");
fflush(fpinDir); fclose(fpinDir); fclose(fpin);} int readpin(int
pinnum){ int value; FILE *inval; inval =
fopen("/sys/class/gpio/gpio48/value", "r");
fseek(inval,0,SEEK_SET);
fscanf(inval,"%d",&value);
fclose(inval); return
value;} void writepin(int pinnum, int value){ FILE *val;
char buf[5]; char buf2[50] = "/sys/class/gpio/gpio";
sprintf(buf,"%i",pinnum);
strcat(buf2,strcat(buf,"/value")); val =
fopen(buf2, "w"); fseek(val,0,SEEK_SET);
fprintf(val,"%d",value);
fflush(val);
fclose(val);}void pauseSec(int sec){ time_t now,later;
now = time(NULL); later = time(NULL);
while((later - now) < (double)sec) later =
time(NULL);}void pauseNanoSec(long nano){ struct timespec tmr1;
tmr1.tv_sec = 0; tmr1.tv_nsec = nano;
} void read_dht11_dat(){ uint8_t laststate = 1; uint8_t
counter = 0; uint8_t j = 0, i; float f; /*
fahrenheit */ dht11_dat[0] = dht11_dat[1] = dht11_dat[2] = dht11_dat[3]
= dht11_dat[4] = 0; /* pull pin down for 18 milliseconds */
setDirection(48,0); //OUT PUT Direction writepin(48,0);
usleep(18000); /* then pull it up for 40 microseconds */
writepin(48,1); usleep(40); /* prepare to read the pin */
setDirection(48,1); //IN PUT Direction /* detect change and read
data */ for ( i = 0; i < MAXTIMINGS; i++ ) { counter = 0;
while ( readpin(48) == laststate ) { counter++;
usleep( 1 ); if ( counter == 255 ) {
break; } } laststate = readpin(48);
if ( counter == 255 ) break; /* ignore first 3
transitions */ if ( (i >= 4) && (i % 2 == 0) ) {
/* shove each bit into the storage bytes */ dht11_dat[j / 8] <<=
1; if ( counter > 16 ) dht11_dat[j / 8] |= 1;
j++; } } /* * check we read 40 bits (8bit x 5 ) +
verify checksum in the last byte * print it out if data is good
*/ /*if ( (j >= 40) && (dht11_dat[4] == ( (dht11_dat[0] +
dht11_dat[1] + dht11_dat[2] + dht11_dat[3]) & 0xFF) ) ) {*/ f =
dht11_dat[2] * 9. / 5. + 32; printf( "Humidity = %d.%d %%
Temperature = %d.%d *C (%.1f *F)\n", dht11_dat[0], dht11_dat[1],
dht11_dat[2], dht11_dat[3], f ); /*}else { printf( "Data not
good, skip\n" ); }*/}int main() { while ( 1 ) {
read_dht11_dat(); pauseSec( 1 ); /* wait 1sec to refresh */ }
return(0);}Thank you......*
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