ESP8266 Community Forum

Posted: **Sun Nov 15, 2015 5:28 pm**

Hi,

I am using a ESP8266 SP12E devkit V2 and want to transmit values from my AM2302 DHT22 temp. and humid. sensor.

The sketch itself works fine (output to serial), but as soon as I add one additional line (that has nothing to do with DHT22 or the humidity var) its getting crazy ...

This is how it works:

Code: Select all


void loop()
{
  delay(dht.getMinimumSamplingPeriod());
  float humidity = dht.getHumidity();
  float temperature = dht.getTemperature();

  Serial.println(String(millis()));
//  Serial.println("Uptime: " + String(millis()/60000) +" min  " + String(millis()/1000) + " sec");
  
  Serial.print(humidity, 1);
  Serial.print("\t\t");
  Serial.println(temperature, 1);

In this case the output looks like:
........
WiFi connected
Server started
10.0.0.29
6811
45.2 24.2
8816
45.2 24.2

You can see this one line that is commented out.

As soon as I comment it in:

Code: Select all


void loop()
{
  delay(dht.getMinimumSamplingPeriod());
  float humidity = dht.getHumidity();
  float temperature = dht.getTemperature();

  Serial.println(String(millis()));
  Serial.println("Uptime: " + String(millis()/60000) +" min  " + String(millis()/1000) + " sec");
  
  Serial.print(humidity, 1);
  Serial.print("\t\t");
  Serial.println(temperature, 1);

this is what I get:

........
WiFi connected
Server started
10.0.0.29
6811
Uptime: 0 min 6 sec
6553649.0 24.2
8816
Uptime: 0 min 8 sec
6553649.0 24.2

The humidity value is just scrap.
I have no idea how this can happen ...
Does anyone have a hint for me ?

BR
Gawan

Posted: **Fri Dec 04, 2015 3:26 am**

Check the sensor type declaration at the top. I did this just yesterday and if you have the wrong one it works but gives rubbish values

Courty

Posted: **Fri Dec 04, 2015 12:42 pm**

The library is very important. Some of the DHT library won't work correctly. Set the correct DHT in library constructor. See examples that come with library itself.

Posted: **Mon Dec 07, 2015 5:29 am**

Gawan wrote:Hi,

I am using a ESP8266 SP12E devkit V2 and want to transmit values from my AM2302 DHT22 temp. and humid. sensor.

The sketch itself works fine (output to serial), but as soon as I add one additional line (that has nothing to do with DHT22 or the humidity var) its getting crazy ...

This is how it works:
................................

this is what I get:

........
WiFi connected
Server started
10.0.0.29
6811
Uptime: 0 min 6 sec
6553649.0 24.2
8816
Uptime: 0 min 8 sec
6553649.0 24.2

The humidity value is just scrap.
I have no idea how this can happen ...
Does anyone have a hint for me ?

BR
Gawan

Hi there, this DHT library uses strict timing when the void from the library is run, use an interrupt driven library, try searching the github....(the line is having an effect on timing).....

https://github.com/rDuinoStar/rDHT11--DHT11-Arduino-Lib

I have used this when there have been "issues".......

ESP8266 Community Forum

Strange behaviour of DHT22 humidity sensor (crazy numbers)

Strange behaviour of DHT22 humidity sensor (crazy numbers)

Re: Strange behaviour of DHT22 humidity sensor (crazy number

Re: Strange behaviour of DHT22 humidity sensor (crazy number

Re: Strange behaviour of DHT22 humidity sensor (crazy number