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Page 110
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
int main(int argc, char **argv)
{
char buffer[25];
int fd = open("/sys/bus/iio/devices/iio:device0/name", O_RDONLY);
read(fd, buffer, 25);
close(fd);
printf("%s", buffer);
fd = open("/sys/bus/iio/devices/iio:device0/in_temp_input", O_RDONLY);
read(fd, buffer, 25);
close(fd);
int temp;
sscanf(buffer, "%d", &temp);
printf("%f\n\r", temp / 1000.0);
fd = open("/sys/bus/iio/devices/iio:device0/in_humidityrelative_input", O_RDONLY);
read(fd, buffer, 25);
close(fd);
int hum;
sscanf(buffer, "%d", &hum);
printf("%f\n\r", hum / 1000.0);
}
Page 112
#define _DEFAULT_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
FILE *doCommand(char *cmd)
{
FILE *fp = popen(cmd, "r");
if (fp == NULL)
{
printf("Failed to run command %s \n\r", cmd);
exit(1);
}
return fp;
}
void checkDht11()
{
FILE *fd = doCommand("sudo dtparam -l");
char output[1024];
int txfound = 0;
char indicator[] = "dht11 gpiopin=4";
char command[] = "sudo dtoverlay dht11 gpiopin=4";
while (fgets(output, sizeof(output), fd) != NULL)
{
printf("%s\n\r", output);
fflush(stdout);
if (strstr(output, indicator) != NULL)
{
txfound = 1;
}
}
if (txfound == 0)
{
fd = doCommand(command);
}
pclose(fd);
}
int main(int argc, char **argv)
{
char buffer[25];
checkDht11();
int fd = open( "/sys/bus/iio/devices/iio:device0/name", O_RDONLY);
read(fd, buffer, 25);
close(fd);
printf("%s", buffer);
fd = open( "/sys/bus/iio/devices/iio:device0/in_temp_input", O_RDONLY);
read(fd, buffer, 25);
close(fd);
int temp;
sscanf(buffer, "%d", &temp);
printf("%f\n\r", temp / 1000.0);
fd = open("/sys/bus/iio/devices/iio:device0/in_humidityrelative_input", O_RDONLY);
read(fd, buffer, 25);
close(fd);
int hum;
sscanf(buffer, "%d", &hum);
printf("%f\n\r", hum / 1000.0);
}
