DHT 22 battery sensor MySensors 2.01

pettib

@Maurice-Krijtenberg
I'm using an existing board so everything is already connected. I have the sensor on pin 3. Sadly it was not that easy 🤔

dbemowsk

You can have the sensor connected to any data pin. When I built my first DHT 22 node I was using one of the newbie PCBs and I mistakenly connected the sensor to PIN5 instead of PIN3. I didn't realize it right away and I was not getting any readings. Once I realized my mistake I just changed the sketch to PIN5 and everything worked. I recently updated it to 2.01 and made sure I checked that. Still going strong.

pettib

@dbemowsk can you please share your sketch ?
And witch library for dht22 are you using ?

//PT

hek

Not sure which DHT library you're using. But in the one provided with the mysensors examples you'll have to wait a bit while the sensor does its work, before fetching temp/hum.

wait(dht.getMinimumSamplingPeriod());
Serial.print(dht.getTemperature());

dbemowsk

@pettib said:

@dbemowsk can you please share your sketch ?
And witch library for dht22 are you using ?

I used the sketch from the examples. What I forgot to mention is that when I used the DHT library that I had installed from my old 1.54 setup, I got errors. If you look at the library linked on the Github page, there is a link to a zip file that they point you to at the bottom of the description. The zip file that is linked there is not the same as the files shown in the Github code pages. DO NOT use the zip file for the 2.01 example. That looked like the same files that I had in my old library that I had for the old 1.54 sketch at a quick glance. If you copy and paste the code shown in the dht.h and the dht.cpp files into your DHT library folder it should work.

pettib

Hi again.

Now i made a sketch that almost work.
If i run it with debug enabled it works fine but when i run it with debug disabled it dosen´t work.
Please help me to find the problem.

/**
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2015 Sensnology AB
 * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 *******************************
 *
 * REVISION HISTORY
 * Version 1.0: Henrik EKblad
 * Version 1.1 - 2016-07-20: Converted to MySensors v2.0 and added various improvements - Torben Woltjen (mozzbozz)
 * 
 * DESCRIPTION
 * This sketch provides an example of how to implement a humidity/temperature
 * sensor using a DHT11/DHT-22.
 *  
 * For more information, please visit:
 * http://www.mysensors.org/build/humidity
 * 
 */

// Enable debug prints
//#define MY_DEBUG

// Enable and select radio type attached 
#define MY_RADIO_NRF24
//#define MY_RADIO_RFM69
//#define MY_RS485
#define MY_NODE_ID 23 //Uterum

#include <SPI.h>
#include <MySensors.h>  
#include <DHT.h>
#include <Wire.h>

#define         READ_SAMPLE_INTERVAL         (10)    //define how many samples you are going to take in normal operation
#define         READ_SAMPLE_TIMES            (5)     //define the time interal(in milisecond) between each samples in  
#define         VREF 3.3f

// Set this to the pin you connected the DHT's data pin to
#define DHT_DATA_PIN 3

// Set this offset if the sensor has a permanent small offset to the real temperatures
#define SENSOR_TEMP_OFFSET -3.4

// Sleep time between sensor updates (in milliseconds)
// Must be >1000ms for DHT22 and >2000ms for DHT11
static const uint64_t UPDATE_INTERVAL = 60000;

// Force sending an update of the temperature after n sensor reads, so a controller showing the
// timestamp of the last update doesn't show something like 3 hours in the unlikely case, that
// the value didn't change since;
// i.e. the sensor would force sending an update every UPDATE_INTERVAL*FORCE_UPDATE_N_READS [ms]
static const uint8_t FORCE_UPDATE_N_READS = 10;

#define CHILD_ID_HUM 0
#define CHILD_ID_TEMP 1

#ifdef MY_DEBUG 
  unsigned long SLEEP_TIME = 60000; // Sleep time between reads (in milliseconds)
#else 
  unsigned long SLEEP_TIME = 900000; // Sleep time between reads (in milliseconds)
#endif


#define SKETCH_NAME "Temp_Humid_Bat_Uterum"                // Change to a fancy name you like
#define SKETCH_VERSION "2.1"                    // Your version

float lastTemp;
float lastHum;
uint8_t nNoUpdatesTemp;
uint8_t nNoUpdatesHum;
bool metric = true;

MyMessage msgHum(CHILD_ID_HUM, V_HUM);
MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
DHT dht;

//=========================
// BATTERY VOLTAGE DIVIDER SETUP
// 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
#define VBAT_PER_BITS 0.003363075  
#define VMIN 1.9                                  //  Vmin (radio Min Volt)=1.9V (564v)
#define VMAX 3.0                                  //  Vmax = (2xAA bat)=3.0V (892v)
int batteryPcnt = 0;                              // Calc value for battery %
int batLoop = 0;                                  // Loop to help calc average
int batArray[3];                                  // Array to store value for average calc.
int BATTERY_SENSE_PIN = A0;                       // select the input pin for the battery sense point
//=========================

void presentation()  
{ 
  // Send the sketch version information to the gateway
  sendSketchInfo(SKETCH_NAME, SKETCH_VERSION);

  // Register all sensors to gw (they will be created as child devices)
  present(CHILD_ID_HUM, S_HUM);
  present(CHILD_ID_TEMP, S_TEMP);

  metric = getConfig().isMetric;
}


void setup()
{
  dht.setup(DHT_DATA_PIN); // set data pin of DHT sensor
  if (UPDATE_INTERVAL <= dht.getMinimumSamplingPeriod()) {
    Serial.println("Warning: UPDATE_INTERVAL is smaller than supported by the sensor!");
  }
  // Sleep for the time of the minimum sampling period to give the sensor time to power up
  // (otherwise, timeout errors might occure for the first reading)
  sleep(dht.getMinimumSamplingPeriod());
  analogReference(INTERNAL);             // For battery sensing
  delay(2000);

  
  #ifdef MY_DEBUG 
    Serial.println("***Debug Activated***");
    Serial.print("Sleep_Time: ");
    Serial.print((SLEEP_TIME / 1000)/60);
    Serial.println(" min");    
  #else 
    Serial.println("***Debug Deactivated***");
    Serial.print("Sleep_Time: ");
    Serial.print((SLEEP_TIME / 1000)/60);
    Serial.println(" min");  
  #endif

}


void loop()      
{  
  // Force reading sensor, so it works also after sleep()
  dht.readSensor(true);

  // Get temperature from DHT library
  float temperature = dht.getTemperature();
  if (isnan(temperature)) {
    Serial.println("Failed reading temperature from DHT!");
  } else if (temperature != lastTemp || nNoUpdatesTemp == FORCE_UPDATE_N_READS) {
    // Only send temperature if it changed since the last measurement or if we didn't send an update for n times
    lastTemp = temperature;
    if (!metric) {
      temperature = dht.toFahrenheit(temperature);
    }
    // Reset no updates counter
    nNoUpdatesTemp = 0;
    temperature += SENSOR_TEMP_OFFSET;
    send(msgTemp.set(temperature, 1));

    #ifdef MY_DEBUG
    Serial.print("T: ");
    Serial.println(temperature);
    #endif
  } else {
    // Increase no update counter if the temperature stayed the same
    nNoUpdatesTemp++;
  }

  // Get humidity from DHT library
  float humidity = dht.getHumidity();
  if (isnan(humidity)) {
    Serial.println("Failed reading humidity from DHT");
  } else if (humidity != lastHum || nNoUpdatesHum == FORCE_UPDATE_N_READS) {
    // Only send humidity if it changed since the last measurement or if we didn't send an update for n times
    lastHum = humidity;
    // Reset no updates counter
    nNoUpdatesHum = 0;
    send(msgHum.set(humidity, 1));

    #ifdef MY_DEBUG
    Serial.print("H: ");
    Serial.println(humidity);
    #endif
  } else {
    // Increase no update counter if the humidity stayed the same
    nNoUpdatesHum++;
  }

    //Read batteries
  batM();
  //Sleep!
  sleep(SLEEP_TIME);
}


void batM() //The battery calculations
{
   delay(500);
   // Battery monitoring reading
   int sensorValue = analogRead(BATTERY_SENSE_PIN);    
   delay(500);
   
   // Calculate the battery in %
   float Vbat  = sensorValue * VBAT_PER_BITS;
   int batteryPcnt = static_cast<int>(((Vbat-VMIN)/(VMAX-VMIN))*100.);
   Serial.print("Battery percent: "); Serial.print(batteryPcnt); Serial.println(" %");  
   
   // Add it to array so we get an average of 3 (3x20min)
   batArray[batLoop] = batteryPcnt;
  
   if (batLoop > 2) {  
     batteryPcnt = (batArray[0] + batArray[1] + batArray[2] + batArray[3]);
     batteryPcnt = batteryPcnt / 3;
 
   if (batteryPcnt > 100) {
     batteryPcnt=100;
 }
 
     Serial.print("Battery Average (Send): "); Serial.print(batteryPcnt); Serial.println(" %");
       sendBatteryLevel(batteryPcnt);
       batLoop = 0;
      }
     else 
     {
     batLoop++;
     }
}

dbemowsk

Out of curiosity, could it be this:

#ifdef MY_DEBUG 
  unsigned long SLEEP_TIME = 60000; // Sleep time between reads (in milliseconds)
#else 
  unsigned long SLEEP_TIME = 900000; // Sleep time between reads (in milliseconds)
#endif

It may not be that it is not working, but that your sleep time is so long that you are not seeing the updates. Why are you changing the sleep time at all based on debug?

pettib

@dbemowsk
@dbemowsk
The reason that I use different sleep time is that this is a battery powered unit, and when debug I don't want to whait for 15 minutes to see the readings. I don't understand why the long sleep will stop me from get the readings ? It's the sleep between readings I change with this function.

dbemowsk

Just to rule it out, keep the same sleep time for both and see if your readings update the same as in debug mode. You can always change it back once you know it is working.

pettib

@dbemowsk I run that way now. Same time for both with debug and without. It works well with debug activated but not with debug inactive. Same time on both.

DHT 22 battery sensor MySensors 2.01

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