💬 Air Humidity Sensor - DHT

[joaoabs]

For the ones looking for a library that makes this DHT sketch work, mysensors have compiled a set of libraries that include this DHT.h and many others. Just go to https://www.mysensors.org/about/arduino#optional---install-external-mysensors-examples (yes, the name is not intuitive, maybe the keyword library would make it more obvious?), or jump directly to here and follow the standard library instructions. It took me two hours to find this, hope it saves time for future followers of mysensors like myself.

Good luck!

[joaoabs]

Here is the set of libraries where you can find the DHT.h: https://github.com/mysensors/MySensorsArduinoExamples/archive/master.zip

[Pavel Polititsky]

If I use this string in a code "sleep(dht.getMinimumSamplingPeriod());" DHT22 (AM2320) always read NaN
else DHT22 working, but never sleeping
What im doing wrong?

[joaoabs]

Where are you reading this "NaN"?
I sometimes also have it in my OpenHab controller webpage when the node doesn't communicate for a while... But when it does, it changes to the value it read from the sensor.

Try to see in the GW if there is traffic comming from that node. Usualy you can read there the values.

Good luck!

[Pavel Polititsky]

In a serial debug of the sensor module
It write something like "Failed to read data humidity (temperature)
Also no send any data to gateway

Without getMinimumSamplingPeriod I've receiving hum & temp through gateway

[gohan]

DHT sensor is not very fast, it needs some times between initialization and the different readings

[Maschler]

Hi
this program doesn’t work with my setup. For the Gateway I am using a Ardunio nano as a serial Gateway. Thus, I am using the GatewaySerial.ino. Even the Node is based on an Arduino nano with a DHT22 connected. The general communication between both seems to work. But I do not receive any sensor data. When testing the setup with another library for the dht sensor, it works fine (without sending to the gateway, only serial Monitor). Because I am new in the mysensors community there is perhaps a simple mistake which I don’t see… I hope you can help me finding my mistake.
Here is a short extract of the Debugging Information’s. As far as I see there are no data transferred.
Gateway:

0;255;3;0;9;0 MCO:BGN:INIT GW,CP=RRNGA---,VER=2.3.0
0;255;3;0;9;4 TSM:INIT
0;255;3;0;9;6 TSF:WUR:MS=0
0;255;3;0;9;9 TSM:INIT:TSP OK
0;255;3;0;9;12 TSM:INIT:GW MODE
0;255;3;0;9;15 TSM:READY:ID=0,PAR=0,DIS=0
0;255;3;0;9;19 MCO:REG:NOT NEEDED
0;255;3;0;14;Gateway startup complete.
0;255;0;0;18;2.3.0
0;255;3;0;9;23 MCO:BGN:STP
0;255;3;0;9;29 MCO:BGN:INIT OK,TSP=1
0;255;3;0;9;1907 TSF:MSG:READ,255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
0;255;3;0;9;1913 TSF:MSG:BC
0;255;3;0;9;1916 TSF:MSG:FPAR REQ,ID=255
0;255;3;0;9;1920 TSF:CKU:OK,FCTRL
0;255;3;0;9;1923 TSF:MSG:GWL OK
0;255;3;0;9;4047 TSF:MSG:SEND,0-0-255-255,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
0;255;3;0;9;5136 TSF:MSG:READ,255-255-0,s=187,c=3,t=3,pt=0,l=0,sg=0:
255;187;3;0;3;
0;255;3;0;9;7150 TSF:MSG:READ,255-255-0,s=155,c=3,t=3,pt=0,l=0,sg=0:
255;155;3;0;3;
0;255;3;0;9;9164 TSF:MSG:READ,255-255-0,s=123,c=3,t=3,pt=0,l=0,sg=0:
255;123;3;0;3;
0;255;3;0;9;11179 TSF:MSG:READ,255-255-0,s=91,c=3,t=3,pt=0,l=0,sg=0:
255;91;3;0;3;
Sensor:
16 MCO:BGN:INIT NODE,CP=RRNNA---,VER=2.3.0
25 TSM:INIT
26 TSF:WUR:MS=0
29 TSM:INIT:TSP OK
30 TSM:FPAR
1250 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
1368 TSF:MSG:READ,0-0-255,s=255,c=3,t=8,pt=1,l=1,sg=0:0
1373 TSF:MSG:FPAR OK,ID=0,D=1
1571 TSF:MSG:READ,0-0-255,s=255,c=3,t=8,pt=1,l=1,sg=0:0
1774 TSF:MSG:READ,0-0-255,s=255,c=3,t=8,pt=1,l=1,sg=0:0
1977 TSF:MSG:READ,0-0-255,s=255,c=3,t=8,pt=1,l=1,sg=0:0
3257 TSM:FPAR:OK
3258 TSM:ID
3259 TSM:ID:REQ
3267 TSF:MSG:SEND,255-255-0-0,s=187,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
5274 TSM:ID
5275 TSM:ID:REQ
5283 TSF:MSG:SEND,255-255-0-0,s=155,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
7290 TSM:ID
7291 TSM:ID:REQ
7299 TSF:MSG:SEND,255-255-0-0,s=123,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
9306 TSM:ID
9307 TSM:ID:REQ
9315 TSF:MSG:SEND,255-255-0-0,s=91,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
11322 !TSM:ID:FAIL
11323 TSM:FAIL:CNT=1
11325 TSM:FAIL:DIS
11327 TSF:TDI:TSL
21330 TSM:FAIL:RE-INIT
21332 TSM:INIT
21335 TSM:INIT:TSP OK
21337 TSM:FPAR

[bgunnarb]

Hi!
What controller are you using?
From the logs it seems that the sensor is asking for an ID but does not get any.
Node ID is handed out by the controller. Or else you have to set the node ID in the sketch. What does the sketch look like?

[Maschler]

Hi
thanks for reply. I am using this sketch: https://github.com/mysensors/MySensors/blob/development/examples/GatewaySerial/GatewaySerial.ino
The only thing I changed is the radio type and I disabled the inclusion mode.

[bgunnarb]

Yes but the issue is with the sensor node. What sketch are you using there?

[Maschler]

Oh. I am using the sketch in from above and only changed the radio module.

[Maschler]

@bgunnarb
You are right. I had to define a sensor id and now it works perfectly :) Thank you very much!

[roachgf85]

Note: Double check your DHT11 module! The pinouts of the PCB of my DHT11 module differed from those in this article. My leftmost pin was Data out, the middle pin was VCC and the right was GND.

[cnerone]

Hi all,
I recoded this sketch and I posted on GitHub (1 year ago, and I updated it today). It runs good from 1 year with no issues.
I don't know why it's still not merged in master branch. I forgot to do some action??
Can anyone help me? please.
Meanwhile you can download and use it; this is its link:
https://github.com/cnerone/MySensorsArduinoExamples/blob/master/examples/DhtTemperatureAndHumiditySensor/DhtTemperatureAndHumiditySensor.ino

[mfalkvidd]

@cnerone no you did 't forget anything. It is just that the external examples don't get much attention and are a bit truoublesome (due to the need of handling third party libraries).

[rmalbers]

I used the code that cnerone has in his comment below with a nano and DHT22 and it worked great. For my nano I did have to use the 'old' bootloader for the program to download into the nano correctly with the arduino IDE. The code in the example here wouldn't compile for me, I think because someone changed the DHT library but for some reason kept the name the same so I ran into some kind of conflicts with variables. I wish when people modified libraries they would give them new/different names because the IDE does not have a good way of handling multiple libraries with the same name. BTW: That is not a MySensors issue, it's the IDE.

[rmalbers]

Also, I could not get a clean compile/download to a arduino mini 3.3v with 168 processor. From what I could find there is not enough memory to handle the newest mysensor libraries, at least that's what some people are saying in forums. I didn't spend much time on it and moved on to other arduinos.

[catchra]

For any one that needs it this is how I got the DHT22 to work.
This is my poor attempt at trying to get the DHT22 to work as the original code
https://github.com/cnerone/MySensorsArduinoExamples/blob/master/examples/DhtTemperatureAndHumiditySensor/DhtTemperatureAndHumiditySensor.ino
will not compile for me.

// Enable debug prints
#define MY_DEBUG

// Enable and select radio type attached 
#define MY_RADIO_RF24
//#define MY_RADIO_RFM69
//#define MY_RS485

#define MY_RF24_CE_PIN 9
#define MY_RF24_CS_PIN 10

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

// Set this to the pin you connected the DHT's data pin to
#define DHTPIN 2     // what digital pin we're connected to
#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321

#define CHILD_ID_HUM 0
#define CHILD_ID_TEMP 1

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

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);
  
}

void setup()
{
  dht.begin(); // set data pin of DHT sensor

}

void loop()      
{  
 delay(2000);
 // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit (isFahrenheit = true)
  float f = dht.readTemperature(true);

  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    return;
  }

  // Compute heat index in Fahrenheit (the default)
  float hif = dht.computeHeatIndex(f, h);
  // Compute heat index in Celsius (isFahreheit = false)
  float hic = dht.computeHeatIndex(t, h, false);
  

    send(msgTemp.set(f, 1));
    send(msgHum.set(h, 1));

  }

[skywatch]

@catchra This bit might be important.....
"This example uses a modified version of the external DHT library, which is included in the MySensors external examples. Please install it and restart the Arduino IDE before trying to compile."

Did you do this already?

[catchra]

@skywatch
ya i did try that 1st but it did not work so I tried to get it to work with the updated lib and so far it has been working well