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momenso / node-dht-sensor

Node.js Humidity and Temperature sensor addon
GNU Lesser General Public License v3.0
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Incorrect Temp and Humidity values #18

Closed hawkerboy7 closed 9 years ago

hawkerboy7 commented 9 years ago

Hi thanks for this module!

However I do get strange temp and humidity values:

info  DH11        →  Temperature: 588.80C, humidity: 870.40%

When I breath very close to the sensor the humidity increases to over 1400% and temp around 716.80C. Do you know what went wrong?

Some images on google showed a resistor had to be placed in between pin 1 and 2 (4k7). I did this and also removed it but the values seemed to stay the same so it didn't appear to have any effect.

Do you know what's wrong?

Thanks in advance!

Ohh and also I had to sudo apt-get install automake on my RaspberryPiB+ and mkdir m4 inside the bcm2835-1.42 folder to get the make command working. It's a clean install of raspbian 2015-02-16 so maybe add it to the readme? Some users might benifit from it :)

momenso commented 9 years ago

I've seen this happen before when I switched between the DHT22 to the DHT11 sensor without changing the sensor type setting in my code.

This happen because although the library can handle both DHT11 and DHT22 sensor you need to specify which one are you using. They are compatible but use different communication protocols which need different handling in order to get the correct readout value.

So, first thing you should check your code if either the initialize or readSpec function call is specifying the correct sensor type (i.e. 11 for the DHT11 and 22 for the DHT22). Please note that the first example in the README file uses an DHT22 (aka AM2302).

Also regarding automake and the m4 directory, you should not need to worry about these if you're using a clean install of raspian and bcm2834 v1.44. Is that what you have? Not sure about bcm2835-1.42 that you said you're using.

hawkerboy7 commented 9 years ago

Thank you! I am getting good readings now. I used 22 and not 11 as you said.

Yes I used a clean install of raspian but not bcm2834 v1.44. On the website (bcm2835) it says on paragraph 4 that you should use this link: http://www.airspayce.com/mikem/bcm2835/bcm2835-1.42.tar.gz.

But now it works great! Thanks! =D