DHT11

[jeri]

I just follow this instruction:

http://www.hobbyist.co.nz/?q=documentations/wiring-up-dht11-temp-humidity-sensor-to-your-arduino

I think like this I can just read the serial port with visa, or not?

[Nathan_B.]

If you don't want to use LIFA you can just create a serial monitor if that is all you need. 

[jeri]

After a long time trying, now I can read data from DHT11 by serial port. I reinstalled the VISTA drivers and now it's working as I want.

[Sambo]

A working, modified version of Nathan's LIFA DHTXX LV09 Rev B.zip:

https://decibel.ni.com/content/message/51334?tstart=0#51334

Cheers

[Morvy187]

Thankssssssssssss For you allllllllllllllllllll
it Works

[Sambo]

For some reason I couldn't read Analog inputs after reading the DHT sensor no matter what I try. So I updated the LIFA firmware with DHT code from the Arduino site: http://playground.arduino.cc/Main/DHTLib, which is a much cleaner implementation than the Adafruit's.

Now it works fine! Check the attached 'DHT_Test.lvproj', after you upload the modified LIFA_Base, of course.

Best regards,

Samir

[Morvy187]

thank you Very much Sambo for you effort and the good work it have been very helpfull thank you sooooooo much again

[1cecream]

Hi Sambo,

First of all I'd like to applaud you for all the provided material. I have a slight problem however when using the code:

Sometimes at the start or mid-way of running the program I get extremely high spikes as shown in the following picture:

Note* those two peaks corresponds to the point in time where I began the program. 

This doesn't happen on a consistent basis, but provided that I require data coming from the DHT11 to maintain absolute accuracy (clashes with other programming if otherwise), it occurs too frequently. Are there any reasons you can think of as to why these spikes are being generated?

My initial thoughts:

1. Programming error

2. Faulty wiring

3. Faulty DHT11

4. EMI (Electro-magnetic interference)

Any thoughts or suggestions would be greatly appreciated!

[Nathan_B.]

I wonder if it just the fact that the DHT11 is extremely slow and the first data point sent out is garbage data.  To test this, you can put a delay before acquiring the first data point.

Alternatively, or maybe in addition to, if the garbage data is always outside of the range of the sensor, you can discard such data points (since they are not possible with the sensor anyways).

[1cecream]

That probably explains why I see those spikes as soon as I run the program. But what about the spikes I see randomly appearing mid-way?