dht11_dht22_cds_test.ino

//
//  dht11_dht22_cds_test.ino - a sample sketch that outputs the sensor data in JSON..
//
//  This program uses the following libraries.//
//  https://github.com/adafruit/DHT-sensor-library
//
#include "DHT.h"

DHT dht11(2, DHT11);
DHT dht22(3, DHT22);

#define CDS_PIN 0
char buf[256];

void setup() {
  Serial.begin(9600);
  while(!Serial) {}
  
  dht11.begin();
  dht22.begin();
}

void loop() {
  create_dht_sensor_message(buf, 256, "home_dht11", dht11.readTemperature(), dht11.readHumidity());
  Serial.println(buf);
    
  delay(1000);

  create_dht_sensor_message(buf, 256, "home_dht22", dht22.readTemperature(), dht22.readHumidity());
  Serial.println(buf);
  
  delay(1000);

  int cds_val = analogRead(CDS_PIN);
  create_cds_sensor_message(buf, 256, "home_cds", cds_val);
  Serial.println(buf);

  delay(3000);
}

void create_cds_sensor_message(char *buf, int buf_len, char *name, int cds_val)
{
  snprintf(
    buf, buf_len,
    "{\"name\":\"%s\", \"cds\": %d, \"tick_count\":%d}",
    name, cds_val, millis());
}

void create_dht_sensor_message(char *buf, int buf_len, char *name, float t, float h)
{
  char th_str[8], tl_str[8];
  char hh_str[8], hl_str[8];
  
  create_float_string(t, th_str, 8, tl_str, 8);
  create_float_string(h, hh_str, 8, hl_str, 8);
  
  snprintf(
    buf, buf_len,
    "{\"name\":\"%s\", \"temperature\": %s.%s, \"humidity\":%s.%s, \"tick_count\":%d}",
    name, th_str, tl_str, hh_str, hl_str, millis());
}

void create_float_string(float val, char *h_str, int h_str_len, char *l_str, int l_str_len)
{
  int val_h = (int)val;
  int val_l = (int)(val * 100) % 100;
  snprintf(h_str, h_str_len, "%d", val_h);
  snprintf(l_str, l_str_len, "%02d", val_l);
}