Temp/Humidity/Light Sensor on battery

[Dheeraj]

After a long time tried making a node with temperature, relative humidity and light sensors.
Running sensor node on 9v battery..actually i have bought ample of 9v batteries. sensor node is running for last 15 days.. ignore the dip in the battery levels due to non-battery mode .

LDR and DHT11 sensors connected on PCB..

final product

[Dwalt]

@Dheeraj Very nice. Do you mind sharing your sketch?

[Dheeraj]

@Dwalt

actually the sketch is simple.

#include <SPI.h> 
#include <MySensor.h>  
#include <DHT.h>  

#define CHILD_ID_HUM 0
#define CHILD_ID_TEMP 1
#define CHILD_ID_LIGHT 2
#define HUMIDITY_SENSOR_DIGITAL_PIN 4
#define BATTERY_SENSE_PIN  A0  // select the input pin for the battery sense point
#define LIGHT_SENSOR_ANALOG_PIN A1

unsigned long SLEEP_TIME = 60000; // Sleep time between reads (in milliseconds)

MySensor gw;
DHT dht;
float lastTemp;
float lastHum;
boolean metric = true; 
MyMessage msgHum(CHILD_ID_HUM, V_HUM);
MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
MyMessage msg(CHILD_ID_LIGHT, V_LIGHT_LEVEL);
int oldBatteryPcnt = 0;
int battLoop =0;
int lightLevel =0;
int lastLightLevel =0;

void setup()  
{ 
  gw.begin(NULL,15);
  dht.setup(HUMIDITY_SENSOR_DIGITAL_PIN); 

  // Send the Sketch Version Information to the Gateway
  gw.sendSketchInfo("Temp Humidity Light", "1.0");

  // Register all sensors to gw (they will be created as child devices)
  gw.present(CHILD_ID_HUM, S_HUM);
  gw.present(CHILD_ID_TEMP, S_TEMP);
  gw.present(CHILD_ID_LIGHT, S_LIGHT_LEVEL);
  
  metric = gw.getConfig().isMetric;
  check_batt();
}

void loop()      
{  
  delay(dht.getMinimumSamplingPeriod());

  float temperature = dht.getTemperature();
  if (isnan(temperature)) {
      Serial.println("Failed reading temperature from DHT");
  } else if (temperature != lastTemp) {
    lastTemp = temperature;
    if (!metric) {
      temperature = dht.toFahrenheit(temperature);
    }
    gw.send(msgTemp.set(temperature, 1));
    Serial.print("T: ");
    Serial.println(temperature);
  }
  
  float humidity = dht.getHumidity();
  if (isnan(humidity)) {
      Serial.println("Failed reading humidity from DHT");
  } else if (humidity != lastHum) {
      
      lastHum = humidity;
      gw.send(msgHum.set(humidity, 1));
      Serial.print("H: ");
      Serial.println(humidity);
  }
  
  lightLevel = (analogRead(LIGHT_SENSOR_ANALOG_PIN))/10.23; 
  if (lightLevel != lastLightLevel) {
      Serial.println(lightLevel);
      gw.send(msg.set(lightLevel));
      lastLightLevel = lightLevel;
  }
  battLoop++;
  if (battLoop > 10)
  {
      check_batt();
      battLoop=0;
  }
  gw.sleep(SLEEP_TIME); //sleep a bit
  
  
}

void check_batt()
{
  // get the battery Voltage
  int sensorValue = analogRead(BATTERY_SENSE_PIN);
  Serial.println(sensorValue);
  
  // 1M, 470K divider across battery and using internal ADC ref of 1.1V
  // Sense point is bypassed with 0.1 uF cap to reduce noise at that point
  // ((1e6+470e3)/470e3)*1.1 = Vmax = 3.44 Volts
  // 3.44/1023 = Volts per bit = 0.003363075
  // vout = (sensorvalue x 3.3) / 1023
  //vin = vout /  (R2/(R1+R2)); 
 
  float batteryV  = ( sensorValue * 0.003225806 ) / 0.3; // divide R2/(R1+R2)
  int batteryPcnt = sensorValue / 10 ;
  if ( batteryPcnt > 100 )
  batteryPcnt = 100;
  
  Serial.print("Battery Voltage: ");
  Serial.print(batteryV);
  Serial.println(" V");
  Serial.print("Battery percent: ");
  Serial.print(batteryPcnt);
  Serial.println(" %");

  if (oldBatteryPcnt != batteryPcnt)
  {
    // Power up radio after sleep
    gw.sendBatteryLevel(batteryPcnt);
    oldBatteryPcnt = batteryPcnt;
  }

}
//```