DHT11 Arduino pro mini no temp readings

[Mr_sensor]

Hi,

I'm trying to get my first sensor working. A DHT11 temp/ humidity sensor. I followed the instructions from the build part on Mysensors. Uploaded the sketch and had a look at the serial monitor.
There it appeared that no temperatures are coming up. So I had a look at the connections and all seems fine to me. What could be the problem? Power?
Also, having a look at the serial log, does it communicate with the gateway? I think so, but which lines are referring to that?
The parts with: TSF:MSG:READ,0-0-1,s=255,c=3,t=27,pt=1,l=1,sg=0:1 ?

Any advise on how to get the DHT11 to work? Thanks.

Using the DHTlibrary as mentioned in the instructions.
Arduino 1.8.2
Mysensors 2.1.1
Arduino pro mini ordered from aliexpress I am not sure which version I have both 3.3 volt and 5volt version (how to determine?).

link text
link text

0 MCO:BGN:INIT NODE,CP=RNNNA--,VER=2.1.1
4 TSM:INIT
4 TSF:WUR:MS=0
12 TSM:INIT:TSP OK
14 TSM:INIT:STATID=1
16 TSF:SID:OK,ID=1
18 TSM:FPAR
18 TSM:FPAR:STATP=0
20 TSM:ID
22 TSM:ID:OK
24 TSM:UPL
32 TSF:MSG:SEND,1-1-0-0,s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=OK:1
47 TSF:MSG:READ,0-0-1,s=255,c=3,t=25,pt=1,l=1,sg=0:1
53 TSF:MSG:PONG RECV,HP=1
55 TSM:UPL:OK
57 TSM:READY:ID=1,PAR=0,DIS=1
71 TSF:MSG:SEND,1-1-0-0,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=OK:0100
79 TSF:MSG:READ,0-0-1,s=255,c=3,t=15,pt=6,l=2,sg=0:0100
90 TSF:MSG:SEND,1-1-0-0,s=255,c=0,t=17,pt=0,l=5,sg=0,ft=0,st=OK:2.1.1
100 TSF:MSG:SEND,1-1-0-0,s=255,c=3,t=6,pt=1,l=1,sg=0,ft=0,st=OK:0
2117 TSF:MSG:SEND,1-1-0-0,s=255,c=3,t=11,pt=0,l=22,sg=0,ft=0,st=OK:TemperatureAndHumidity
2129 TSF:MSG:SEND,1-1-0-0,s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=OK:1.1
2144 TSF:MSG:SEND,1-1-0-0,s=0,c=0,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
2154 TSF:MSG:SEND,1-1-0-0,s=1,c=0,t=6,pt=0,l=0,sg=0,ft=0,st=OK:
2160 MCO:REG:REQ
2166 TSF:MSG:SEND,1-1-0-0,s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=OK:2
2226 TSF:MSG:READ,0-0-1,s=255,c=3,t=27,pt=1,l=1,sg=0:1
2232 MCO:PIM:NODE REG=1
2234 MCO:BGN:STP
2236 MCO:SLP:MS=1000,SMS=0,I1=255,M1=255,I2=255,M2=255
2242 MCO:SLP:TPD
2244 MCO:SLP:WUP=-1
2246 MCO:BGN:INIT OK,TSP=1
Failed reading temperature from DHT!
Failed reading humidity from DHT
2269 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
2279 MCO:SLP:TPD
2281 MCO:SLP:WUP=-1
Failed reading temperature from DHT!
Failed reading humidity from DHT
2304 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
2314 MCO:SLP:TPD
2316 MCO:SLP:WUP=-1
Failed reading temperature from DHT!
Failed reading humidity from DHT
2336 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
2347 MCO:SLP:TPD
2349 MCO:SLP:WUP=-1```

Any help would be appreciated. Thanks. W.

[hek]

Well, something is wrong with either the wiring or sensor. If you have a multimeter, you should probably do a continuity test on the connections.

[Mr_sensor]

@hek Thanks for the reply. I just did a test with my multimeter and measuring at the dht11 it shows 3.46 so that should be ok right?
I used the DHT11 some time ago with an esp8266 and than it was working fine. Could the pin 3 data be the problem?

[tonnerre33]

Hi, which sensor do you use ?
A DHT put on a pcb or without pcb ?
If you haven't a DHT with pcb, you need to put a 5k resistor between pin 1 and 2 of the DHT ;)
More information here : https://www.mysensors.org/dl/57c3ec0c4d04abe84cd93e0f/design/DHT11.pdf

[Mr_sensor]

@tonnerre33 No I have one with pcb.

[Mr_sensor]

@Mr_sensor Stil get the message

Failed reading temperature from DHT!
Failed reading humidity from DHT

Also tried it with an dh22 I had (included a pull-up resistor between vcc and data) but get the same result. What can I do to get this working?
If I use the arduino pro mini for an other sensor they are working fine (tested with a magnet-reed switch).

[gohan]

have you set all the waiting/delay times and the initialization before reading the temperature (as seen in the examples)?

[Mr_sensor]

This is the sketch I'm using.

/**
 * 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
 * 
 */
#define MY_NODE_ID 2
#define MY_PARENT_NODE_ID 0
#define MY_PARENT_NODE_IS_STATIC

// Enable debug prints
#define MY_DEBUG

// Enable and select radio type attached 
#define MY_RADIO_NRF24
//#define MY_RADIO_RFM69
//#define MY_RS485
 
#include <SPI.h>
#include <MySensors.h>  
#include <DHT.h>


// 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 0

// 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

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;


void presentation()  
{ 
  // Send the sketch version information to the gateway
  sendSketchInfo("TemperatureAndHumidity", "1.1");
  
  // 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 = getControllerConfig().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());
}


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++;
  }

  // Sleep for a while to save energy
  sleep(UPDATE_INTERVAL); 
}

[Mr_sensor]

since I did not get these Dht11 or Dht22 working, I decided to try an other sensor type to see if that would work better.
So I connected a HTU21D sensor and included the library from sparkfun. Using there demo sketch I can see the sensor is working fine:

HTU21D Example!
Time:192 Temperature:20.8C Humidity:998.0%
Time:1318 Temperature:20.8C Humidity:47.3%
Time:2445 Temperature:20.7C Humidity:47.4%
Time:3571 Temperature:20.7C Humidity:47.4%
Time:4698 Temperature:20.7C Humidity:47.5%
Time:5824 Temperature:20.7C Humidity:47.5%
Time:6948 Temperature:20.7C Humidity:47.6%
Time:8075 Temperature:20.7C Humidity:47.6%
Time:9201 Temperature:20.7C Humidity:47.6%

But when I include the "adapted" Mysensors sketch I found here in the forum it seems the temperatures are not read or something else is wrong?

This is what is in the log file in a ongoing loop:

MCO:BGN:INIT NODE,CP=RNNNA--,VER=2.1.1
4 TSM:INIT
4 TSF:WUR:MS=0
12 TSM:INIT:TSP OK
14 TSM:INIT:STATID=2
16 TSF:SID:OK,ID=2
18 TSM:FPAR
18 TSM:FPAR:STATP=0
20 TSM:ID
22 TSM:ID:OK
22 TSM:UPL
28 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=OK:1
47 TSF:MSG:READ,0-0-2,s=255,c=3,t=25,pt=1,l=1,sg=0:1
53 TSF:MSG:PONG RECV,HP=1
55 TSM:UPL:OK
57 TSM:READY:ID=2,PAR=0,DIS=1
63 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=OK:0100
75 TSF:MSG:READ,0-0-2,s=255,c=3,t=15,pt=6,l=2,sg=0:0100
86 TSF:MSG:SEND,2-2-0-0,s=255,c=0,t=17,pt=0,l=5,sg=0,ft=0,st=OK:2.1.1
96 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=6,pt=1,l=1,sg=0,ft=0,st=OK:0
2107 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=11,pt=0,l=8,sg=0,ft=0,st=OK:Humidity
2119 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=OK:2.0
2129 TSF:MSG:SEND,2-2-0-0,s=0,c=0,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
2140 TSF:MSG:SEND,2-2-0-0,s=1,c=0,t=6,pt=0,l=0,sg=0,ft=0,st=OK:
2146 MCO:REG:REQ
2164 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=OK:2
2220 TSF:MSG:READ,0-0-2,s=255,c=3,t=27,pt=1,l=1,sg=0:1
2226 MCO:PIM:NODE REG=1
2228 MCO:BGN:INIT OK,TSP=1
2 MCO:BGN:INIT NODE,CP=RNNNA--,VER=2.1.1
6 TSM:INIT
6 TSF:WUR:MS=0
14 TSM:INIT:TSP OK
16 TSM:INIT:STATID=2
18 TSF:SID:OK,ID=2
20 TSM:FPAR
20 TSM:FPAR:STATP=0
22 TSM:ID
24 TSM:ID:OK
26 TSM:UPL
30 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=OK:1
57 TSF:MSG:READ,0-0-2,s=255,c=3,t=25,pt=1,l=1,sg=0:1
63 TSF:MSG:PONG RECV,HP=1
67 TSM:UPL:OK
67 TSM:READY:ID=2,PAR=0,DIS=1
73 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=OK:0100
92 TSF:MSG:READ,0-0-2,s=255,c=3,t=15,pt=6,l=2,sg=0:0100
102 TSF:MSG:SEND,2-2-0-0,s=255,c=0,t=17,pt=0,l=5,sg=0,ft=0,st=OK:2.1.1
112 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=6,pt=1,l=1,sg=0,ft=0,st=OK:0
2121 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=11,pt=0,l=8,sg=0,ft=0,st=OK:Humidity
2134 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=OK:2.0
2144 TSF:MSG:SEND,2-2-0-0,s=0,c=0,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
2154 TSF:MSG:SEND,2-2-0-0,s=1,c=0,t=6,pt=0,l=0,sg=0,ft=0,st=OK:
2160 MCO:REG:REQ
2164 TSF:MSG:SEND,2-2-0-0,s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=OK:2
2234 TSF:MSG:READ,0-0-2,s=255,c=3,t=27,pt=1,l=1,sg=0:1
2240 MCO:PIM:NODE REG=1
2242 MCO:BGN:INIT OK,TSP=1

This is the sketch I use now I had to adopt it since it seemed to be for an older version of Mysensors. I'm no programmer so it might be messed up somehow :)

/**
 * 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
 * 
 HTU21D Humidity Sensor
 Hardware Connections (Breakoutboard to Arduino):
 -VCC = 3.3V
 -GND = GND
 -SDA = A4 (use inline 330 ohm resistor if your board is 5V)
 -SCL = A5 (use inline 330 ohm resistor if your board is 5V)
 */

 
#define MY_NODE_ID 2
#define MY_PARENT_NODE_ID 0
#define MY_PARENT_NODE_IS_STATIC

// Enable debug prints
#define MY_DEBUG

// Enable and select radio type attached 
#define MY_RADIO_NRF24
//#define MY_RADIO_RFM69
//#define MY_RS485
 
#include "SparkFunHTU21D.h"
#include <MySensors.h>  
#include <Wire.h>
#include <SPI.h>

// 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

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


void presentation()  
{ 
 // Send the Sketch Version Information to the Gateway                                                                                                                     
  sendSketchInfo("Humidity", "2.0");      
   
 // 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 = getControllerConfig().isMetric;
}

                                                                                                                                                  
unsigned long SLEEP_TIME = 60000; // Sleep time between reads (in milliseconds)                                                                                             
                                                                                                                                                                        
                                                                                                                                                               
                                                                                                                                                                        
//Create an instance of the object                                                                                                                                          
HTU21D myHumidity;                                                                                                                                                         

                                                                                                                                                                                                                                                                                                                             
MyMessage msgHum(CHILD_ID_HUM, V_HUM);                                                                                                                                      
MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);                                                                                                                                   
                                                                                                                                                                                                                                                                                                                                                  
void loop()                                                                                                                                                                 
{                                                                                                                                                                           
  float temperature = myHumidity.readTemperature();                                                                                                                         
  //if (!metric) {                                                                                                                                                            
  //    temperature = (temperature * 1.8) + 32.0;                                                                                                                             
  //}                                                                                                                                                                         
  send(msgTemp.set(temperature, 1));                                                                                                                                     

  float humidity = myHumidity.readHumidity();                                                                                                                               
  send(msgHum.set(humidity, 1));                                                                                                                                         
                                                                                                                                                                        
  sleep(SLEEP_TIME); //sleep a bit  
                                                                                                                                       
}

Can anyone advise me on the code and the error log so I understand what's going on and what needs to be done to get it working? Thanks a lot.

W.

[mfalkvidd]

@Mr_sensor I think you need to add

void setup() {
    myHumidity.begin();
}

Without that, the sensor/sensor library is not initialized.

(I looked at sparkfun's example sketch)

[Mr_sensor]

:) Great! That helped a lot. I Kicked that out when reading the Converting a sketch from 1.5 to 2.x article.

4911 TSF:MSG:SEND,2-2-0-0,s=1,c=1,t=0,pt=7,l=5,sg=0,ft=0,st=OK:20.4
4954 TSF:MSG:SEND,2-2-0-0,s=0,c=1,t=1,pt=7,l=5,sg=0,ft=0,st=OK:50.2
4962 MCO:SLP:MS=60000,SMS=0,I1=255,M1=255,I2=255,M2=255
4968 MCO:SLP:TPD

Now I only have to find out what to use for mqtt to read this sensor values. Thats still not very clear to me:
Guess it would be something like:
mygateway1-out/2/2/0/0/ or 2/2/0/0/1 ?

Would it be possible to have something like this:

mygateway-out/2/2/Temperature ?

[Mr_sensor]

Ok found out what topic is send to mqtt turned out to be:
mygateway1-out/2/1/1/0/1 or mygateway1-out/2/0/1/0/1

How to get an % and "C" to this topic value?

[gohan]

Just use any mqtt client and subscribe to topic # , you will be able to see all messages and pick the one you are looking for